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tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 1 copyright ? 2005, trinamic motion control gmbh & co kg trinamic ? motion control gmbh & co kg hamburg, germany www.trinamic.com features the tmc246 / tmc246a (1) is a dual full bridge driver ic for bipolar stepper motor control application s. the integrated unique sensorles s stall detection (pat. pend.) s tallguard? makes it a good choice for applications, where a reference point is needed, but where a switch is not desired. its ability to predict an overload makes the tmc246 an optimum choice for drives, where a high reliability is desired. the tmc246 is r ealized in a hvcmos technology combined with low - rds - on high efficiency mosfets (pat. pend.). it allows driving a coil current of up to 1500ma even at high environment temperatures. its low current consumption and high efficiency together with the miniatur e package make it a perfect solution for embedded motion control and for battery powered devices. internal dacs allow microstepping as well as smart current control. the device can be contro lled by a serial interface (spi? i ) or by analog / digital input signals. short circuit, temperature, undervoltage and overvoltage protection are integrated. ? sensorless stall detection stall guard? and load measurement integrated ? control via spi with easy - t o - use 12 bit protocol or external analog / digital signals ? short circuit, overvoltage and over temperature protection integrated ? status flags for overcurrent, open load, over temperature, temperature pre - warning, undervoltage ? integrated 4 bit dacs allow up to 16 times microstepping via spi (can be expanded to 64 microsteps) ? any resolution via analog control ? mixed decay feature for smooth motor operation ? slope control user programmable to reduce electromagnetic emissions ? chopper frequency programmable via a single capacitor or external clock ? current control allows cool motor and driver operation ? 7v to 34v motor supply voltage (a - type) ? up to 1500ma output current and more than 800ma at 105c ? 3.3v or 5v operation for digital part ? low power dissipation via low rds - on power stage ? standby and shutdown mode available (1) the term tmc246 in this datasheet always refers to the tmc246a and the tmc246. the major differences in the older tmc246 are explicitly marked with non - a - type. the tmc246a brings a number of enhance ments and is fully backward compatible to the tmc246. tmc24 6 /a C data sheet high current microstep stepper motor driver with stallguard?, protection / diagnostics and spi interface
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 2 copyright ? 2005, trinamic motion control gmbh & co kg features ................................ ................................ ................................ ................................ .............. 1 pinning ................................ ................................ ................................ ................................ .................. 5 p ackage codes ................................ ................................ ................................ ................................ .... 5 pqfp44 d imensions ................................ ................................ ................................ ............................ 6 application circuit / block diagram ................................ ................................ ....................... 7 p in f unctions ................................ ................................ ................................ ................................ ...... 7 layout consideration s ................................ ................................ ................................ ................ 8 control via the spi interface ................................ ................................ ................................ ... 9 s erial data word tran smitted to tmc246 ................................ ................................ ....................... 9 s erial data word tran smitted from tmc246 ................................ ................................ .................. 9 t ypical winding curre n t values ................................ ................................ ................................ ..... 10 b ase current control via ina and inb in spi mode ................................ ................................ ....... 10 c ontrolling the power down mode via the spi interface ................................ ........................... 10 o pen load detection ................................ ................................ ................................ ........................ 11 s tandby and shutdown mode ................................ ................................ ................................ ........... 11 p ower saving ................................ ................................ ................................ ................................ .... 11 stall detection ................................ ................................ ................................ ............................. 12 u sing the sensorless load measurement ................................ ................................ ...................... 12 i mpleme nting sensorless sta ll detection ................................ ................................ ..................... 12 protection functions ................................ ................................ ................................ ................. 13 o vercurrent protectio n and diagnosis ................................ ................................ ........................ 13 o vertemperature prote ction and diagnosis ................................ ................................ ................. 13 o vervoltage protectio n and enn pin behavior ................................ ................................ ............ 13 c hopper principle ................................ ................................ ................................ ......................... 14 c hopper cycle / u sing the mixed decay feature ................................ ................................ ............ 14 a dapting the sine wav e for smooth motor o peration ................................ ................................ .. 15 b lank t ime ................................ ................................ ................................ ................................ ......... 15 b lank time settings ................................ ................................ ................................ .......................... 15 classical non - spi control mode (s tand alone mode) ................................ .................. 16 p in functions in stan d alone mode ................................ ................................ ................................ .. 16 i nput signals for mic rostep control in st and alone mode ................................ .......................... 16 calculation of the e xternal components ................................ ................................ ....... 17 s ense r esistor ................................ ................................ ................................ ................................ . 17 e xamples for sen se resistor settings ................................ ................................ .......................... 17 h igh side overcurrent detection resistor r sh ................................ ................................ ............ 17 m aking the circuit sh ort circuit proof ................................ ................................ ......................... 18 o scillator c apacitor ................................ ................................ ................................ ...................... 19 t able of oscillator f requencies ................................ ................................ ................................ .... 19 p ullup resistors on unused inputs ................................ ................................ ................................ 19 p ower supply sequenci ng considerations ................................ ................................ .................... 19 s lope c ontrol r esistor ................................ ................................ ................................ ................. 20 e xample for slope set tings ................................ ................................ ................................ ............ 20 absolute maximum rat ings ................................ ................................ ................................ ....... 21 electrical character istics ................................ ................................ ................................ ..... 21 o perational r ange ................................ ................................ ................................ .......................... 21 dc c haracteristics ................................ ................................ ................................ ......................... 22 ac c haracteristics ................................ ................................ ................................ ......................... 23 t hermal p rotection ................................ ................................ ................................ ......................... 23
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 3 copyright ? 2005, trinamic motion control gmbh & co kg t hermal c haracteristics ................................ ................................ ................................ ................ 24 t ypical p ower d issipation at hig h load / high temperature ................................ ........................ 24 spi interface timing ................................ ................................ ................................ ...................... 25 p ropagation t imes ................................ ................................ ................................ ........................... 25 u sing the spi interface ................................ ................................ ................................ ................... 25 spi f ilter ................................ ................................ ................................ ................................ .......... 25 esd protection ................................ ................................ ................................ ............................... 26 application note: ex tending the microste p resolution ................................ ............. 27 documentation revisi on ................................ ................................ ................................ ............ 28
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 4 copyright ? 2005, trinamic motion control gmbh & co kg life support policy trinamic motion control gmbh & co kg does not autho rize or warrant any of its products for use in life support systems, without the specific written consent of trinamic motion control gmbh & co kg. life support systems are equipment intended to support or sustain life, and whose failure to perform, when properly used in accordance with instructions provided, can be reasonably expected to result in personal injury or death. ? trinamic motion control gmbh & co kg 2005 information given in this data sheet is believed t o be accurate and reliable. however no responsibility is assumed for the consequences of its use nor for any infringement of patents or other rights of third parties, which may result from its use. specifications subject to change without notice.
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 5 copyright ? 2005, trinamic motion control gmbh & co kg pinnin g package codes type package temperature range lead free (rohs) code/marking tmc246a pqfp44 automotive (1) yes tmc246a - pa tmc246 pqfp44 automotive (1) from date code 30/04 tmc246 - pa (1) ics are not tested according to automotive standards, but are u sable within the complete automotive temperature range. 1 9 4 12 17 14 15 16 22 18 21 13 19 20 33 25 30 41 44 43 42 39 36 35 40 38 37 34 tmc 246 / 236a qfp44 bl2 ob1 ob1 ob2 ob2 brb vsb inb agnd slp ina gnd vs vt vcc - - - ann oa1 oa2 oa2 oa1 bra vsa sra gnd sdo sdi sck srb csn bl1 osc enn spe 2 3 5 6 7 8 10 11 24 23 27 26 29 28 32 31
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 6 copyright ? 2005, trinamic motion control gmbh & co kg pqfp44 dimensions ref min. max. a 12 c 10 d 1 e - 1.6 f 0.09 0.2 g 0.05 0.15 h 0.30 0.45 i 0.45 0.75 k 0.8 l 0 0.08 all dimensions are in mm. l: co - planarity of pins i e f c k h d g a
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 7 copyright ? 2005, trinamic motion control gmbh & co kg applicatio n circuit / block diagram pin functions pin function pin function vs motor supply voltage vt short to gnd detection compar ator C connect to vs if not used vcc 3.0 - 5.5v supply voltage for analog and logic circuits gnd digital / power ground agnd analog ground (reference for sra, srb, osc, slp, ina, inb, slp) osc oscillator capacitor or external clock input for chopper ina a nalog current control phase a inb analog current control input phase b sck clock input of serial interface sdo data output of serial interface (tri - state) sdi data input of serial interface csn chip select input of serial interface enn device enable (lo w active), and overvoltage shutdown input spe enable spi mode (high active). tie to gnd for non - spi applications ann enable analog current control via ina and inb (low active) slp slope control re sistor. bl1, bl2 digital blank time select sra, srb bridg e a/b current sense resistor input oa1, oa2 output of full - bridge a ob1, ob2 output of full - bridge b vsa, vsb supply voltage for bridge a/b bra, brb bridge a/b sense resistor r s r sh coil a +v m coil b 100f 220nf n n n n p p p p tmc246 vt vs 4 dac 4 dac ina inb vref refsel pwm-ctrl ann spe 1 0 0 1 current controlled gate drivers current controlled gate drivers slp r slp pwm-ctrl osc control & diagnosis parallel control spi- interface refsel gnd agnd under- voltage tem- perature osc vcc 1nf 100nf +v cc sck sdi sdo csn enn bl2 bl1 [mdbn] [pha] [err] [phb] stand alone mode [mdan] oa1 oa2 ob1 ob2 vsb vsa sra bra r s srb brb [...]: function in stand alone mode load mesure- ment vcc/2
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 8 copyright ? 2005, trinamic motion control gmbh & co kg layout considerations for optimal operation of the circuit a careful board la yout is important, because of the combination of high current chopper operation coupled with high accuracy threshold comparators. please pay special attention to a massive grounding. depending on the required motor current, either a single massive ground p lane or a ground plane plus star connection of the power traces may be used. the schematic shows how the high current paths can be routed separately, so that the chopper current does not flow through the systems gnd - plane. tie the tmc246s agnd and gnd to the gnd plane. additionally, use enough filtering capacitors located near to the boards power supply input and small ceramic capacitors near to the power supply connections of the tmc246. use low inductance sense resistors, or add a ceramic capacitor in parallel to each resistor to avoid high voltage spikes. in some applications it may become necessary to introduce additional rc - filtering into the vt and sra / srb line, as shown in the schematic, to prevent spikes from triggering the short circuit protect ion or the chopper comparator. be sure to connect all pins of the pqfp package for each of the double/quad output pins externally. each two of these output pins should be treated as if they were fused to a single wide pin (as shown in the drawing). each two pins are used as cooling fin for one of the eight integrated output power transistors. use massive motor current traces on all these pins and multiple vias, if the output trace is changed to a different layer near the package. a symmetrical layout on all of the oa and ob pins is required, to ensure proper heat dissipation on all output transistors. otherwise proper function of the thermal protection can not be guaranteed! a multi - layer pcb shows superior thermal performance, because it allows usage of a massive gnd plane, which will act as a heat spreader. the heat will be coupled vertically from the output traces to the gnd plane, since vertical heat distribution in pcbs is quite effective. heat dissipation can be improved by attaching a heat sink t o the package directly. please be aware, that long or thin traces to the sense resistors may add substantial resistance and thus reduce output current. the same is valid for the high side shunt resistor. use short and straight traces to avoid parasitic in ductivities, because these can generate large voltage spikes and emv problems. + vm gnd gnd - plane r sb r sa r s h c vm 100 r optional voltage divider vs vt tmc 236 / tmc 246 100 r 100 r 3 . 3 - 10 nf sra srb optional filter agnd gnd 100 nf vsa vsb bra brb r div
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 9 copyright ? 2005, trinamic motion control gmbh & co kg control via the spi interface the spi data word sets the current and polarity for both coils. by applying consecutive values, describing a sine and a cosine wave, the motor can be driven in microsteps. every microstep is initiated by its own telegram. please refer to the description of the analog mode for details on the waveforms required. the spi interface timing is described in the timing section. we recommend the tmc428 t o automatically generate the required telegrams and motor ramps for up to three motors. serial data word transmitted to tmc246 (msb transmitted first) bit name function remark 11 mda mixed decay enable phase a 1 = mixed decay 0 = current flow from oa1 to oa2 1 = mixed decay 0 = current flow from ob1 to ob2 serial data word transmitted from tmc246 (msb transmitted first) bit name function remark 11 ld2 load indicator bit 2 msb 10 ld 1 load indicator bit 1 9 ld0 load indicator bit 0 lsb 8 1 always 1 1 = chip off due to over 1 = pre 1 = undervoltage on vs
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 10 copyright ? 2005, trinamic motion control gmbh & co kg typical winding current values current setting ca3..0 / cb3..0 percentage of current typical trip voltage of th e current sense comparator (internal reference or analog input voltage of 2v is used) 0000 0% 0 v (bridge continuously in slow decay condition) 0001 6.7% 23 mv 0010 13.3% 45 mv ... ... 1110 93.3% 317 mv 1111 100% 340 mv the current values corresp ond to a standard 4 bit dac, where 100%=15/16. the contents of all registers is cleared to 0 on power - on reset or disable via the enn pin, bringing the chip to a low power standby mode. all spi inputs have schmitt - trigger function. base current control via ina and inb in spi mode in spi mode, the ic can use an external reference voltage for each dac. this allows the adaptation to different motors. this mode is enabled by tying pin ann to gnd. a 2.0v input voltage gives full scale current of 100%. in this case, the typical trip voltage of the current sense comparator is determined by the input voltage and the dac current setting (see table above) as follows: v trip,a = 0.17 v ina ? percentage spi current setting a v trip,b = 0.17 v inb ? percentage spi cur rent setting b a maximum of 3.0v v in is possible. multiply the percentage of base current setting and the dac table to get the overall coil current. it is advised to operate at a high base current setting, to reduce the effects of noise voltages. this fe ature allows a high resolution setting of the required motor current using an external dac or pwm - dac (see schematic for examples). controlling the power down mode via the spi interface programming current value 0000 for both coils at a time clears the overcurrent flags and switches the tmc246 into a low current standby mode with coils switched off. 47 k 100 nf agnd ina inb ann c - pwm using pwm signal 100 k c - port . 2 8 level via r 2 r - dac 5 1 k 5 1 k 5 1 k 100 k 100 k c - port . 1 c - port . 0 r 1 2 level control r 2 c - port + v c c 10 nf standard function 11 mxa 10 ca3 9 ca2 6 pha - 0 - control word function - - bit enable standby mode and clear error flags 8 ca1 7 ca0 5 mxb 4 cb3 3 cb2 0 phb 2 cb1 1 cb0 0 0 0 0 0 0 0
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 11 copyright ? 2005, trinamic motion control gmbh & co kg open load detection open load is signaled whenever there are more than 14 oscillator cycles without pwm switch off. note that open load de tection is not possible while coil current is set to 0000, because the chopper is off in this condition. the open load flag will then always be read as inactive (0). during overcurrent and undervoltage or over temperature conditions, the open load flag s also become active! due to their principle, the open load flags not only signal an open load condition, but also a torque loss of the motor, especially at high motor velocities. to detect only an interruption of the connection to the motor, it is advis ed to evaluate the flags during stand still or during low velocities only (e.g. for the first or last steps of a movement). standby and shutdown mode the circuit can be put into a low power standby mode by the user, or, automatically goes to standby on vc c undervoltage conditions. before entering standby mode, the tmc246 switches off all power driver outputs. in standby mode the oscillator becomes disabled and the oscillator pin is held at a low state. the standby mode is available via the interface in spi - mode and via the enn pin in non - spi mode. the shutdown mode even reduces supply current further. it can only be entered in spi - mode by pulling the enn pin high. in shutdown additionally all internal reference voltages become switched off and the spi cir cuit is held in reset. power saving the possibility to control the output current can dramatically save energy, reduce heat generation and increase precision by reducing thermal stress on the motor and attached mechanical components. just reduce motor cu rrent during stand still: even a slight reduction of the coil currents to 70% of the current of the last step of the movement, halves power consumption! in typical applications a 50% current reduction during stand still is reasonable.
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 12 copyright ? 2005, trinamic motion control gmbh & co kg stall detection usi ng the sensorless load measurement the tmc246 provides a patented sensorless load measurement, which allows a digital read out of the mechanical load on the motor via the serial interface. to get a readout value, just drive the motor using sine commutation and mixed decay switched off. the load measurement then is available as a three bit load indicator during normal motion of the motor. a higher mechanical load on the motor results in a lower readout value. the value is updated once per fullstep. the load detection is based on the motors back emf, thus the level depends on several factors: - motor velocity: a higher velocity leads to a higher readout value - motor resonance: motor resonances cause a high dynamic load on the motor, and thus measurement may giv e unsatisfactory results. - motor acceleration: acceleration phases also produce dynamic load on the motor. - mixed decay setting: for load measurement mixed decay has to be off for some time before the zero crossing of the coil current. if mixed decay is used , and the mixed decay period is extended towards the zero crossing, the load indicator value decreases. implementing sensorless stall detection the sensorless stall detection typically is used, to detect the reference point without the usage of a switch o r photo interrupter. therefore the actuator is driven to a mechanical stop, e.g. one end point in a spindle type actuator. as soon as the stop is hit, the motor stalls. without stall detection, this would give an audible humming noise and vibrations, which could damage mechanics. to get a reliable stall detection, follow these steps: 1. choose a motor velocity for reference movement. use a medium velocity which is far enough away from mechanical resonance frequencies. in some applications even motor start / stop frequency may be used. with this the motor can stop within one fullstep if a stall is detected. 2. use a sine stepping pattern and switch off mixed decay (at least 1 to 3 microsteps before zero crossing of the wave). monitor the load indicator during mov ement. it should show a stable readout value in the range 3 to 7 (l move ). if the readout is high (>5), the mixed decay portion may be increased, if desired. 3. choose a threshold value l stall between 0 and l move - 1. 4. monitor the load indicator during each ref erence search movement, as soon as the desired velocity is reached. readout is required at least once per fullstep. if the readout value at one fullstep is below or equal to l stall , stop the motor. attention: do not read out the value within one chopper pe riod plus 8 microseconds after toggling one of the phase polarities! 5. if the motor stops during normal movement without hitting the mechanical stop, decrease l stall . if the stall condition is not detected at once, when the motor stalls, increase l stall . v _ max t v ( t ) a _ m a x acceleration constant velocity stall min max t load indicator stall detected ! stall threshold vibration acceleration jerk l move l stall
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 13 copyright ? 2005, trinamic motion control gmbh & co kg protection functions overcurrent protection and diagnosis the tmc246 uses the current sense resistors on the low side to dete ct an overcurrent: whenever a voltage above 0.61v is detected, the pwm cycle is terminated at once and all transistors of the bridge are switched off for the rest of the pwm cycle. the error counter is increased by one. if the error counter reaches 3, the bridge remains switched off for 63 pwm cycles and the error flag is read as active. the user can clear the error condition in advance by clearing the error flag. the error counter is cleared, whenever there are more than 63 pwm cycles without overcurrent . there is one error counter for each of the low side bridges, and one for the high side. the overcurrent detection is inactive during the blank pulse time for each bridge, to suppress spikes which can occur during switching. the high side comparator det ects a short to gnd or an overcurrent, whenever the voltage between vs and vt becomes higher than 0.15 v at any time, except for the blank time period which is logically ored for both bridges. here all transistors become switched off for the rest of the pw m cycle, because the bridge with the failure is unknown. the overcurrent flags can be cleared by disabling and re - enabling the chip either via the enn pin or by sending a telegram with both current control words set to 0000. in high side overcurrent con ditions the user can determine which bridge sees the overcurrent, by selectively switching on only one of the bridges with each polarity (therefore the other bridge should remain programmed to 0000). over temperature protection and diagnosis the circuit switches off all output power transistors during an over temperature condition. the over temperature flag should be monitored to detect this condition. the circuit resumes operation after cool down below the temperature threshold. however, operation near the over temperature threshold should be avoided, if a high lifetime is desired. overvoltage protection and enn pin behavior during disable conditions the circuit switches off all output power transistors and goes into a low current shutdown mode. all re gister contents is cleared to 0, and all status flags are cleared. the circuit in this condition can also stand a higher voltage, because the voltage then is not limited by the maximum power mosfet voltage. the enable pin enn provides a fixed threshold o f ? v cc to allow a simple overvoltage protection up to 40v using an external voltage divider (see schematic). enn r2 c-port (opt.) low=enable, high=disable r1 +v m for switch off at 26 - 29v: at vcc=5v: r1=100k; r2=10k at vcc=3.3v: r1=160k; r2=10k
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 14 copyright ? 2005, trinamic motion control gmbh & co kg chopper p rinciple chopper cycle / using the mixed decay feature the tmc246 uses a quiet fixed frequency chopper. both coils are chopped with a phase shift of 180 degrees. the mixed decay option is realized as a self stabilizing system (pat. fi.), by shortening the fast decay phase, if the on phase becomes longer. it is advised to enable the mixed decay for each phase during the second half of each microstepping half - wave, when the current is meant to decrease. this leads to less motor resonance, especially at medium velocities. with low velocities or during standstill mixed decay should be switched off. in applications requiring high resolution, or using low inductivity motors, the mixed decay mode can also be enabled continuously, to reduce the minimum motor current which can be achieved. when mixed decay mode is continuously on or when using high inductivity motors at low supply voltage, it is advised to raise the chopper frequency to minimum 36khz, because the half chopper frequency could become audible under these conditions. when polarity is changed on one bridge, the pwm cycle on that bridge becomes restarted at once. fast decay switches off both upper transistors, while enabling the lower transistor opposite to the selected polarity. slow decay always enables both lower side transistors. r s e n s e s w c s w o s w c s w o i o n p h a s e : c u r r e n t f l o w s i n t a r g e t d i r e c t i o n r s e n s e i f a s t d e c a y p h a s e : c u r r e n t f l o w s b a c k i n t o p o w e r s u p p l y s w c s w o s w o r s e n s e i s l o w d e c a y p h a s e : c u r r e n t r e - c i r c u l a t i o n s w c s w o s w o s w c oscillator clock resp . external clock actual current phase a target current phase a mixed decay disabled mixed decay enabled on slow decay on fast decay slow decay
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 15 copyright ? 2005, trinamic motion control gmbh & co kg adapting the sine wave for smooth motor operation after reaching the target current in each chopper cycle, both, the slow decay and the fast decay cycle reduce the current by some amount. especially the fast decay cycle has a larger impact. thus, the medium coil current always is a bit lower than the target current. this leads to a flat line in the current shape flowing through the motor. it can be corrected, by applying an offset to the sine shape. in mi xed decay operation via spi, an offset of 1 does the job for most motors. blank time the tmc246 uses a digital blank ing pulse for the current chopper comparators. this prevents current spikes, which can occur during switching action due to capacitive loading, from terminating the chopper cycle. the lowest possible blanking time gives the best results for microstepping: a long blank time leads to a long minimum turn - on time, thus giving an increased lower limit for the current. please remark, that the blank time should cover both, switch - off time of the lower side transistors and turn - on time of the upper side transistors plus some time for the current to settle. thus the complete switching duration should never exceed 1.5s. the tmc246 allows adapting the blank time to the load conditions and to the selected slope in four steps (the effective resulting blank times are ab out 200ns shorter in the non - a - type): blank time settings bl2 bl1 typical blank time gnd gnd 0.6 s gnd vcc 0.9 s vcc gnd 1.2 s vcc vcc 1.5 s t i t a r g e t c u r r e n t c o i l c u r r e n t t i t a r g e t c u r r e n t c o i l c u r r e n t c o i l c u r r e n t d o e s n o t h a v e o p t i m u m s h a p e t a r g e t c u r r e n t c o r r e c t e d f o r o p t i m u m s h a p e o f c o i l c u r r e n t
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 16 copyright ? 2005, trinamic motion control gmbh & co kg classical non - spi control mode (stand alone mode) the driver can be controlled by analog current contro l signals and digital phase signals. to enable this mode, tie pin spe to gnd. in this mode, the spi interface is disabled and the spi input pins have alternate functions. the internal dacs are forced to 1111. pin functions in stand alone mode pin stand alone mode name function in stand alone mode spe (gnd) tie to gnd to enable stand alone mode ann mdan enable mixed decay for bridge a (low = enable) sck mdbn enable mixed decay for bridge b (low = enable) sdi pha polarity bridge a (low = current flow from output oa1 to oa2) csn phb polarity bridge b (low = current flow from output ob1 to ob2) sdo err error output (high = overcurrent on any bridge, or overtemperature). in this mode, the pin is never tristated. enn enn standby mode (high active), hig h causes a low power mode of the device. setting this pin high also resets all error conditions. ina, inb ina, inb current control for bridge a, resp. bridge b. refer to agnd. the sense resistor trip voltage is 0.34v when the input voltage is 2.0v. maxim um input voltage is 3.0v. input signals for microstep control in stand alone mode attention : when transferring these waves to spi operation, please remark, that the mixed decay bits are inverted when compared to stand alone mode. 90 180 270 360 ina inb pha (sdi) phb (csn) mdan (ann) mdbn (sck) use dotted line to improve performance at medium velocities
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 17 copyright ? 2005, trinamic motion control gmbh & co kg calculation of the external components sense resistor choose an appropriate sense resistor (r s ) to set the desired motor current. the maximum motor curr ent is reached, when the coil current setting is programmed to 1111. this results in a current sense trip voltage of 0.34v when the internal reference or a reference voltage of 2v is used. when operating your motor in fullstep mode, the maximum motor cu rrent is as specified by the manufacturer. when operating in sinestep mode, multiply this value by 1.41 for the maximum current (i max ). r s = v trip / i max in a typical application: r s = 0.34v / i max r s : current sense resistor of bridge a, b v trip : pro grammed trip voltage of the current sense comparators i max : desired maximum coil current examples for sense resistor settings r s i max 0.47 ? 723ma 0.43 ? 790ma 0.39 ? 870ma 0.33 ? 1030ma 0.27 ? 1259ma 0.22 ? 1545ma high side overcurrent detection resis tor r sh the tmc246 detects an overcurrent to ground, when the voltage between vs and vt exceeds 150mv. the high side overcurrent detection resistor should be chosen in a way that 100mv voltage drop are not exceeded between vs and vt, when both coils draw t he maximum current. in a sinestep application, this is when sine and cosine wave have their highest sum, i.e. at 45 degrees, corresponding to 1.41 times the maximum current setting for one coil. in a fullstep application this is the double coil current. i n a microstep application: r sh = 0.1v / (1.41 ? i max ) in a fullstep application: r sh = 0.1v / (2 ? i max ) r sh : high side overcurrent detection resistor i max : maximum coil current however, if the user desires to use higher resistance values, a volta ge divider in the range of 10 ? to 100 ? can be used for vt. this might also be desired to limit the peak short to gnd current, as described in the following chapter. attention : a careful pcb layout is required for the sense resistor traces and for the r s h traces.
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 18 copyright ? 2005, trinamic motion control gmbh & co kg making the circuit short circuit proof in practical applications, a short circuit does not describe a static condition, but can be of very different nature. it typically involves inductive, resistive and capacitive components. worst events are u nclamped switching events, because huge voltages can build up in inductive components and result in a high energy spark going into the driver, which can destroy the power transistors. the same is true when disconnecting a motor during operation: never disc onnect the motor during operation! there is no absolute protection against random short circuit conditions, but pre - cautions can be taken to improve robustness of the circuit: in a short condition, the current can become very high before it is interrupte d by the short detection, due to the blanking during switching and internal delays. the high - side transistors allows up to 10a flowing for the selected blank time. the lower the external inductivity, the faster the current climbs. if inductive components a re involved in the short, the same current will shoot through the low - side resistor and cause a high negative voltage spike at the sense resistor. both, the high current and the voltage spikes are a danger for the driver. thus there are a two things to be done, if short circuits are expected: 1. protect sra/srb inputs using a series resistance 2. increase r sh to limit maximum transistor current: use same value as for sense resistors 3. use as short as possible blank time the second measure effectively limits short circuit current, because the upper driver transistor with its fixed on gate voltage of 7v forms a constant current source together with its internal resistance and r sh . a positive side effect is, that only one type of low ohmic resistor is required. the d rawback is, that power dissipation increases slightly. a high side short detection resistor of 0.33 ohms limits maximum high side transistor current to typically 4a. the schematic shows the modifications to be done. however, the effectiveness of these me asures should be tested in the given application. +vm gnd r sb r sa r sh c vm 100r vs vt 100r 100r sra srb gnd 100nf r div internal r div values for reference microstep: 27r fullstep: 18r ina/inb up to3v 18r 12r r sh =r sa =r sb
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 19 copyright ? 2005, trinamic motion control gmbh & co kg oscillator capacitor the pwm oscillator frequency can be set by an external capacitor. the internal oscillator uses a 28k ? resistor to charge / discharge the external capacitor to a trip voltage of 2/3 vcc respectively 1/3 vcc. it can be overdriven using an external cmos level square wave signal. do not set the freq uency higher than 100khz and do not leave the osc terminal open! the two bridges are chopped with a phase shift of 180 degrees at the positive and at the negative edge of the clock signal. f osc : pwm oscillator frequency c osc : oscill ator capacitor in nf table of oscillator frequencies f osc typ. c osc 16.7khz 1.5nf 20.8khz 1.2nf 25.0khz 1.0nf 30.5khz 820pf 36.8khz 680pf 44.6khz 560pf please remark, that an unnecessary high frequency leads to high switching losses in the power t ransistors and in the motor. for most applications a chopper frequency slightly above audible range is sufficient. when audible noise occurs in an application, especially with mixed decay continuously enabled, the chopper frequency should be two times the audible range. for most applications we recommend a frequency of 36.8khz. pullup resistors on unused inputs the digital inputs all have integrated pull - up resistors, except for the enn input, which is in fact an analog input. thus, there are no external p ull - up resistors required for unused digital inputs which are meant to be positive. power supply sequencing considerations upon power up, the driver initializes and switches off the bridge power transistors. however, in order for the internal startup logi c to work properly, the vcc supply voltage has to be at least 1.0v, respectively, the vs supply voltage has to be at least 5.0v. when vs goes up with vcc at 0v, a medium current temporary cross conduction of the power stage can result at supply voltages be tween 2.4v and 4.8v. while this does no harm to the driver, it may hinder the power supply from coming up properly, depending on the power supply start up behavior. in order to prevent this from occurring, either use a dual voltage power supply, or use a local regulator, generating the 5v or 3.3v vcc voltage. please pay attention to the local regulator start up voltage: some newer sw itching regulators do not start before the input voltage has reached 5v. therefore it is recommended to use a standard lin ear regulator like 7805 series or lm317 or a low drop regulator or a switching regulator like the lm2595, starting at relatively low input voltages. [nf] c s 40 1 f osc osc ? ? ?
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 20 copyright ? 2005, trinamic motion control gmbh & co kg slope control resistor the output - voltage slope of the full bridge outputs can be controlled to reduce no ise on the power supply and on the motor lines and thus electromagnetic emission of the circuit. it is controlled by an external resistor at the slp pin. operational range: 0k ? ? r slp ? 100k ? the slp - pin can directly be connected to agnd for the fastes t output - voltage slope (respectively maximum ou t put current). in most applications a minimum external resistance of 10 k ? is recommended to avoid unnecessary high switching spikes. only for non - a - types the slope on the lower transistors is fixed (correspo nding to a 5k ? to 10k ? slope control resistor). for applications where electromagnetic emission is very critical, it might be necessary to add additional lc (or capacitor only) filtering on the motor connections. for these applications emission is lower, i f only slow decay operation is used. please remark, that there is a tradeoff between reduced electromagnetic emissions (slow slope) and high efficiency because of low dynamic losses (fast slope). the following table and graph depict typical behavior mea sured from 15% of output voltage to 85% of output voltage. however, the actual values measured in an application depend on multiple parameters and may stray in a user application. example for slope settings t slp typ. r slp 30ns 2.2k ? 60ns 10k ? 110ns 22k ? 245ns 51k ? 460ns 100k ? 10 100 t slp [ns] @ 10v r slp in kohm 10 5 2 0 20 50 100 t slp [ns] @ 24v 20 50 200 500 1
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 21 copyright ? 2005, trinamic motion control gmbh & co kg absolute maximum ratings the maximum ratings may not be exceeded under any circumst ances. symbol parameter min max unit v s supply voltage (a - type) - 0.3 36 v v s supply voltage (non - a - type) - 0.3 30 v v md supply and bridge voltage max. 20000s (non - a - type: device disabled) 40 v v tr power transistor voltage v oa - v bra , v ob - v brb, v sa - v oa , v sb - v ob (a - type) 40 v v tr power transistor voltage v oa - v bra , v ob - v brb, v sa - v oa , v sb - v ob (non - a - type) 30 v v cc logic supply voltage - 0.5 6.0 v i op output peak current (10s pulse) +/ - 7 a i oc output current (continuous, per bridge) t a ? a ? a ? i logic input voltage - 0.3 v cc +0.3v v v ia analog input voltage - 0.3 v cc +0.3v v i io maximum current to / from digital pins and analog inputs +/ - 10 ma v vt short - to - ground detector input voltage v s - 1v v s +0.3v v t j junction temperature - 40 150 (1) c t stg storage temperature - 55 150 c (1) internally limited electrical characteristics operational range symbol parameter min max unit t ai ambient temperature industrial (1) - 25 125 c t aa ambient temperature auto motive - 40 125 c t j junction temperature - 40 140 c v s bridge supply voltage (a - type) 7 34 v v s bridge supply voltage (non - a - type) 7 28.5 v v cc logic supply voltage 3.0 5.5 v f clk chopper clock frequency 50 khz r slp slope control resistor 0 110 k ? (1) the circuit can be operated up to 140c, but output power derates.
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 22 copyright ? 2005, trinamic motion control gmbh & co kg dc characteristics dc characteristics contain the spread of values guaranteed within the specified supply voltage and temper a ture range unless otherwise specified. typical characteristic s represent the average value of all parts. logic supply voltage: v cc = 3.0 v ... 5.5 v, junction temperature: t j = - 40c 150c, bridge supply voltage: v s = 7 v 34 v (unless otherwise spec i fied) symbol parameter conditions min typ max unit r out ,sink r dson of sink - transistor t j = 25c v s ? ? out,source r dson of source - transistor t j = 25c v s ? ? out,sink r dson of sink - transistor max. t j =150c v s ? ? out,source r dson of source - transistor max. t j =15 0c v s ? ? dio diode forward voltages of o xx mosfet diodes t j = 25c i oxx = 1.05a 0.84 1.12 v v ccuv vcc undervoltage 2.5 2.7 2.9 v v ccok vcc voltage o.k. 2.7 2.9 3.0 v i cc vcc supply current f osc = 25 khz 0.85 1.35 ma i ccstb vcc su pply current standby 0.45 0.75 ma i ccsd vcc supply current shutdown enn = 1 37 70 a v suv vs undervoltage 5.5 5.9 6.2 v v ccok vs voltage o.k. 6.1 6.4 6.7 v i ssm vs supply current with fastest slope setting (static state) v s = 14v, r slp = 0k 6 m a i ssd vs supply current shutdown or standby v s = 14v 28 50 a v ih high input voltage (sdi, sck, csn, bl1, bl2, spe, ann) 2.2 vcc + 0.3 v v v il low input voltage (sdi, sck, csn, bl1, bl2, spe, ann) - 0.3 0.7 v v ihys input voltage hysteresis (sdi, s ck, csn, bl1, bl2, spe, ann) 100 300 500 mv v oh high output voltage (output sdo) - i oh = 1ma vcc C C ol low output voltage (output sdo) i ol = 1ma 0 0.1 0.4 v - i isl low input current (sdi, sck, csn, bl1, bl2, spe, ann) v i = 0 v cc = 3.3 v v cc = 5.0v 2 10 25 70 a a a v ennh high input voltage threshold (input enn) 1/2 vcc v ehys input voltage hysteresis (input enn) 0.1 v ennh
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 23 copyright ? 2005, trinamic motion control gmbh & co kg v osch high input voltage threshold (input osc) tbd 2/3 vcc tbd v v oscl low input voltage threshold ( input osc) tbd 1/3 vcc tbd v v vtd vt threshold voltage (referenced to vs) - 130 - 155 - 180 mv v trip sra / srb voltage at dac=1111 srs sra / srb overcurrent detection threshold 570 615 660 mv v sroffs s ra / srb comparator offset voltage - 10 0 10 mv r inab ina / inb input resistance vin ? ? ac characteristics ac characteristics contain the spread of values guaranteed within the specified supply voltage and temperature range unless othe rwise specified. typical characteristics represent the average value of all parts. logic supply voltage: v cc = 5.0v, bridge supply voltage: v s = 14.0v, ambient temperature: t a = 27c symbol parameter conditions min typ max unit f osc oscillator frequency using internal oscillator c osc = 1nf ? 31 khz t rs , t fs rise and fall time of outputs oxx with r slp =0 v o 15% to 85% i oxx = 800ma 25 ns t rs , t fs rise and fall time of outputs oxx with r slp = 25k ? o 15% to 85% i oxx = 800ma 125 ns t rs , t fs ri se and fall time of outputs oxx with r slp = 50k ? o 15% to 85% i oxx = 800ma 250 ns t bl effective blank time bl1, bl2 = v cc 1.35 1.5 1.65 s t onmin minimum pwm on - time bl1, bl2 = gnd 0.7 s thermal protection symbol parameter conditions min typ max unit t jot thermal shutdown 145 155 165 c t jothys t jot hysteresis 15 c t jwt prewarning temperature 135 145 155 c t jwthys t jwt hysteresis 15 c
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 24 copyright ? 2005, trinamic motion control gmbh & co kg thermal characteristics symbol parameter conditions typ unit r tha12 thermal resistance brid ge transistor junction to ambient, one bridge chopping, fixed polarity soldered to 2 layer pcb 88 k/w r tha22 thermal resistance bridge transistor junction to ambient, two bridges chopping, fixed polarity soldered to 2 layer pcb 68 k/w r tha14 thermal re sistance bridge transistor junction to ambient, one bridge chopping, fixed polarity soldered to 4 layer pcb (pessimistic) 84 k/w r tha24 thermal resistance bridge transistor junction to ambient, two bridges chopping, fixed polarity soldered to 4 layer pcb (pessimistic) 51 k/w typical power dissipation at high load / high temperature coil: l w = 10mh, r w = 5.0 ? chopping with: t duty = 33% on, only slow decay current both brid - ges on current one bridge on ambient temperature t a motor supply voltage v m slope t slp chopper frequency f chop typ total power dissipation p d 560 ma - 105 c 16 v 400 ns 25 khz 490 mw - 800 ma 105 c 16 v 400 ns 25 khz 450 mw 560 ma 125 c 14 v 60ns 20 khz 350 mw 800 ma 125 c 14 v 60ns 20 khz 340 mw 1000 ma - 70 c 28 v 60ns 25 khz 1000 mw - 1500 ma 70 c 28 v 60ns 25 khz 1100 mw
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 25 copyright ? 2005, trinamic motion control gmbh & co kg spi interface timing propagation times (3.0 v ? vcc ? 5.5 v, - 40c ? tj ? 150c; v ih = 2.8v, v il = 0.5v; tr, tf = 10ns; c l = 50pf, unless otherwise specified) symbol parameter conditions min typ max unit f sck sck frequency enn = 0 dc 4 mhz t 1 sck stable before and after csn change 50 ns t ch width of sck high pulse 100 ns t cl width of sck low pulse 100 ns t du sdi setup time 40 ns t dh sdi hold time 50 ns t d sdo delay t ime c l = 50pf 40 100 ns t zc csn high to sdo high impedance *) 50 ns t es enn to sck setup time 30 s t pd csn high to oa / ob output polarity change delay **) 3 t osc + 4 s t ld load indicator valid after oa / ob output polarity change 5 7 s * ) sdo is tristated whenever enn is inactive (high) or csn is inactive (high). **) whenever the pha / phb polarity is changed, the chopper is restarted for that phase. however, the chopper does not switch on, when the sra resp. srb comparator threshold is exceeded upon the start of a chopper period. using the spi interface the spi interface allows either cascading of multiple devices, giving a longer shift register, or working with a separate chip select signal for each device, paralleling all other lines. even when there is only one device attached to a cpu, the cpu can communicate with it using a 16 bit transmission. in this case, the upper 4 bits are dummy bits. spi filter to prevent spikes from changing the spi settings, spi data words are only accepte d, if their length is at least 12 bit. t 1 sdo sdi sck csn t es t 1 t 1 t cl t ch bit 11 bit 10 bit 0 bit 11 bit 10 bit 0 t d t zc t du t dh enn
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 26 copyright ? 2005, trinamic motion control gmbh & co kg esd protection please be aware, that the tmc246 is an esd sensitive device due to integrated high performance mos transistors. esd sensitive device if the ics are manually handled before / during soldering, spec ial precautions have to be taken to avoid esd voltages above 100v hbm (human body model). for automated smd equipment the internal device protection is specified with 1000v cdm (charged device model), tbf. when soldered to the application board, all inpu ts and outputs withstand at least 1000v hbm.
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 27 copyright ? 2005, trinamic motion control gmbh & co kg application note: extending the microstep resolution for some applications it might be desired to have a higher microstep resolution, while keeping the advantages of control via the serial interface. the follo wing schematic shows a solution, which adds two lsbs by selectively pulling up the sra / srb pin by a small voltage difference. please remark, that the lower two bits are inverted in the depicted circuit. a full scale sense voltage of 340mv is assumed. the circuit still takes advantage of completely switching off of the coils when the internal dac bits are set to 0000. this results in the following comparator trip voltages: current setting (msb first) trip voltage 0000xx 0 v 000111 5.8 mv 000110 11. 5 mv 000101 17.3 mv 000100 23 mv ... 111101 334.2 mv 111100 340 mv spi bit 15 14 13 12 11 10 9 8 dac bit /b1 /b0 /a1 /a0 mda a5 a4 a3 spi bit 7 6 5 4 3 2 1 0 dac bit a2 pha mdb b5 b4 b3 b2 phb please see the faq document for more application information. r s sra tmc236 / tmc239 110r 4.7nf opt. 74hc595 c1 q0 q1 q2 q3 q4 q5 q6 q7 q7' /mr c2 /oe sck sdi sdo csn +v cc ds1d 100k /cs sdi sck sdo free for second tmc239 47k 47k 47k /daca.0 /daca.1 /dacb.0 /dacb.1 vcc = 5v 1/2 74hc74 c d q note: use a 74hc4094 instead of the hc595 to get rid of the hc74 and inverter
tm c246 / tmc246a data sheet (v2.0 6 / 20 11 - aug - 10 ) 28 copyright ? 2005, trinamic motion control gmbh & co kg documentation revision version author bd= bernhard dwersteg description v1.00 bd first version, sept. 2003 v2.04 bd added p ower supply sequencing considerations v2.05 bd adapted style, added info on chopper cycle v2.06 bd corrected enn timing in spi section i spi is a trademark of motorola

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