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tmc246 data sheet (v2.01 / sep. 14th, 2005) 1 copyright ? 2005, trinamic motion control gmbh & co kg tmc 246/a ? data sheet high current microstep stepper motor driver with sensorless stall detection, protection / diagnosis and spi interface trinamic ? motion control gmbh & co kg sternstra?e 67 d ? 20357 hamburg germany t +49 - (0) 40 - 51 48 06 - 0 f +49 - (0) 40 - 51 48 06 - 60 www.trinamic.com info@trinamic.com features the tmc246 / TMC246A (1) is a dual full bridge driver ic for bipolar stepper motor control applications. the integrated unique sensorless sta ll detection (pat. pend.) stallguard? 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 opt imum choice for drives, where a high reliability is desired. the tmc246 is realized in a hvcm os technology combined with low-rds-on high efficiency mosfets (pat. pend.). it allows to dr ive a coil current of up to 1500ma even at high environment temperatures. its low current consumpt ion and high efficiency together with the miniature 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 devic e can be controlled by a serial interface (spi? i ) or by analog / digital input signals. short circuit, temperature, undervoltage and overvoltage protection are integrated. ? sensorless stall detection stallguar d? and load measurement integrated ? control via spi with easy-to-use 12 bit pr otocol or external analog / digital signals ? short circuit, overvoltage and overte mperature protection integrated ? status flags for overcurrent, open load, over te mperature, temperature pre-warning, undervoltage ? integrated 4 bit dacs allow up to 16 times microstepping via spi, 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 singl e 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 re fers 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 enhancements and is fully backward compatible to the tmc246.
tmc246 data sheet (v2.01 / sep. 14th, 2005) 2 copyright ? 2005, trinamic motion control gmbh & co kg life support policy trinamic motion control gmbh & co kg does not authorize 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 to be accurate and reliable. however no responsibility is assumed for the consequences of its use nor for any infringement of patents or ot her rights of third parties, which may result form its use. specifications subject to change without notice.
tmc246 data sheet (v2.01 / sep. 14th, 2005) 3 copyright ? 2005, trinamic motion control gmbh & co kg pinning 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 usable 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 4 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 5 copyright ? 2005, trinamic motion control gmbh & co kg application circuit / block diagram r s r sh coil a +v m coil b 100f 220nf n n nn p p pp 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 pin functions pin function pin function vs motor supply voltage vt short to gnd detection comparator ? 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 analog 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 (low 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 resistor. bl1, bl2 digital blank time select sra, srb bridge 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 br a, brb bridge a/b sense resistor
tmc246 data sheet (v2.01 / sep. 14th, 2005) 6 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 accura cy threshold comparators. please pay special attention to a massive grounding. depending on the r equired motor current, either a single massive ground plane 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 separat ely, so that the chopper current does not flow through the system?s gnd-plane. tie the tmc246? s agnd and gnd to the gnd plane. additionally, use enough filtering capacitors located near to t he board?s power supply input and small ceramic capacitors near to the power suppl y connections of the tmc246. use low inductance sense resistors, or add a ceramic capacitor in parallel to each re sistor 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 t he short circuit protection or the chopper comparator. be sure to connect all pins of the pqfp pack age 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 cooli ng fin for one of the eight integrated output power transistors. use massive motor current traces on all these pins and multip le 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 perform ance, 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 e ffective. heat dissipation can be improved by attaching a heat sink to the package directly. please be aware, that long or thin traces to t he 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 i nductivities, because these can gener ate large voltage spikes and emv problems. +vm gnd gnd- plane r sb r sa r sh c vm 100r optional voltage divider vs vt tmc236/ tmc246 100r 100r 3.3 - 10nf sra srb optional filter agnd gnd 100nf vsa vsb bra brb r div
tmc246 data sheet (v2.01 / sep. 14th, 2005) 7 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 to automatically generate the required tel egrams 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 10 ca3 current bridge a.3 msb 9 ca2 current bridge a.2 8 ca1 current bridge a.1 7 ca0 current bridge a.0 lsb 6 pha polarity bridge a ?0? = current flow from oa1 to oa2 5 mdb mixed decay enable phase b ?1? = mixed decay 4 cb3 current bridge b.3 msb 3 cb2 current bridge b.2 2 cb1 current bridge b.1 1 cb0 current bridge b.0 lsb 0 phb polarity bridge b ?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 ld1 load indicator bit 1 9 ld0 load indicator bit 0 lsb 8 1 always ?1? 7 ot overtemperature ?1? = chip off due to overtemperature 6 otpw temperature prewarning ?1? = prewarning temperature exceeded 5 uv driver undervoltage ?1? = undervoltage on vs 4 ochs overcurrent high side 3 pwm cycles with overcurrent within 63 pwm cycles 3 olb open load bridge b no pwm switch off for 14 oscillator cycles 2 ola open load bridge a no pwm switch off for 14 oscillator cycles 1 ocb overcurrent bridge b low side 3 pwm cycl es with overcurrent within 63 pwm cycles 0 oca overcurrent bridge a low side 3 pwm cycl es with overcurrent within 63 pwm cycles
tmc246 data sheet (v2.01 / sep. 14th, 2005) 8 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 the 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 correspond to a standard 4 bi t dac, where 100%=15/16. the contents of all registers is cleared to ?0? on power-on reset or dis able 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 volt age of the current sense co mparator 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 current 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 oper ate at a high base current setting, to reduce the effects of noise voltages. this feature allows a high resolution setting of the required motor current using an external dac or pwm-da c (see schematic for examples). 47k 100nf agnd ina inb ann c- pwm using pwm signal 100k c- port .2 8 level via r2r-dac 51k 51k 51k 100k 100k c- port .1 c- port .0 r1 2 level control r2 c- port +v cc 10nf controlling the power down mode via the spi interface 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 0 000 00 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.
tmc246 data sheet (v2.01 / sep. 14th, 2005) 9 copyright ? 2005, trinamic motion control gmbh & co kg open load detection open load is signaled, whenever there are more t han 14 oscillator cycles without pwm switch off. note that open load detection is not possible while co il current is set to ? 0000?, because the chopper is off in this condition. the open load flag will then alwa ys be read as inactive (?0?). during overcurrent and undervoltage or overtemperature conditions , the open load flags also become active! due to their principle, the open load flags not onl y 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 advised to evaluate t he 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 m ode by the user, or, automatically goes to standby on vcc 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 avail able 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 a ll internal reference voltages become switched off and the spi circuit 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 current during stand still: even a s light 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.
tmc246 data sheet (v2.01 / sep. 14th, 2005) 10 copyright ? 2005, trinamic motion control gmbh & co kg stall detection using the sensorless load measurement the tmc246 provides a patented sensorless load measur ement, which allows a digital read out of the mechanical load on the motor via the serial interfac e. 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. since the load detection is based on the motor? s back emf, the readout results depend 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 give unsatisfactory results. - motor acceleration: acceleration phases also produce dynamic load on the motor. - mixed decay setting: for load measurement mix ed 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 or photo interrupter. therefor e the actuator is driven to a me chanical stop, e.g. one end point in a spindle type actuator. as soon as the stop is hit, t he 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 move ment. 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 st op 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 indi cator during movement. 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 refer ence search movement, as soon as the desired velocity is reached. readout is required at l east once per fullstep. if the readout value at one fullstep is below or equal to l stall , stop the motor. 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_max acceleration constant velocity stall min max t load indicator stall detected! stall threshold vibration acceleration jerk l move l stall
tmc246 data sheet (v2.01 / sep. 14th, 2005) 11 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 detect 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 o ff for 63 pwm cycles and the error flag is read as ?active?. the user can clear the error condition in advance by clearing the erro r 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 fo r the high side. the overcurrent detection is inactive during the blank pulse time for each br idge, to suppress spikes which can occur during switching. the high side comparator detects a short to g nd or an overcurrent, whenever the voltage between vs and vt becomes higher than 0.15 v at any time, exc ept for the blank time period which is logically ored for both bridges. here all transistors become switched off for the rest of the pwm 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 contro l words set to ?0000?. in high side overcurrent conditions 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?). overtemperature 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 overtemperature threshold should be avoided, if a high lifetime is desired. overvoltage protection and enn pin behavior during disable conditions the circuit switches o ff all output power transistors and goes into a low current shutdown mode. all register contents is cleared to ?0?, and a ll status flags are cleared. the circuit in this condition can also stand a higher vo ltage, because the voltage t hen is not limited by the maximum power mosfet voltage. the enable pin enn provides a fixed threshold of ? 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 12 copyright ? 2005, trinamic motion control gmbh & co kg chopper principle chopper cycle / using the mixed decay feature the tmc246 uses a quiet fixed frequency chopper. bo th 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 microsteppi ng 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. w hen mixed decay mode is continuously on or when using high inductivity motors at low supply volt age, it is advised to raise the chopper frequency to 36khz, because the half chopper frequency c ould be audible under these conditions. 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 when polarity is changed on one bridge, the pwm cycl e 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. blank time the tmc246 uses a digital blanking pulse for the cu rrent 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 shoul d never exceed 1.5s. the tmc246 allows to adapt the blank time to t he load conditions and to the selected slope in four steps (the effective resulting blank time s are about 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 13 copyright ? 2005, trinamic motion control gmbh & co kg classical non-spi control mode (stand alone mode) the driver can be controlled by analog current cont rol 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 inter nal 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 = cu rrent flow from output oa1 to oa2) csn phb polarity bridge b (low = cu rrent 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), high c auses 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 t he input voltage is 2.0v. maximum 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 14 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 current 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 re ference or a reference voltage of 2v is used. when operating your motor in fullstep mode, the ma ximum motor current is as specified by the manufacturer. when operating in sinestep mode, multip ly 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 : programmed 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 resistor r sh the tmc246 detects an overcurrent to ground, when the voltage between vs and vt exceeds 150mv. the high side overcurrent detection resist or should be chosen in a way that 100mv voltage drop are not exceeded between vs and vt, when both coils draw the 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 setti ng for one coil. in a fullstep application this is the double coil current. in 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 resi stance values, a voltage 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 sh traces.
tmc246 data sheet (v2.01 / sep. 14th, 2005) 15 copyright ? 2005, trinamic motion control gmbh & co kg making the circuit short circuit proof in practical applications, a short circuit does not descr ibe a static condition, but can be of very different nature. it typically involves inductive, resi stive and capacitive com ponents. worst events are unclamped switching events, because huge voltages c an build up in inductive components and result in a high energy spark going into the driver, which c an destroy the power transis tors. the same is true when disconnecting a motor during operation: ne ver disconnect the motor during operation! there is no absolute protection against random short circuit conditions, but pr e-cautions can be taken to improve robustness of the circuit: in a short condition, the current can become very hi gh before it is interrupted by the short detection, due to the blanking during switching and internal del ays. the high-side transistors allows up to 10a flowing for the selected blank time. the lower the exte rnal inductivity, the faster the current climbs. if inductive components are involved in the short, t he same current will shoot through the low-side resistor and cause a high negative voltage spike at t he 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: us e 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 requir ed. the drawback is, that power dissipation increases slightly. a high side shor t 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 measures 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 16 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 frequency 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. [nf] c s 40 1 f osc osc f osc : pwm oscillator frequency c osc : oscillator 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 l eads to high switching losses in the power transistors and in the motor. for most applicati ons a chopper frequency slightly above audible range is sufficient. when audible noise occurs in an applicat ion, especially with mi xed decay continuously enabled, the chopper frequency should be two times the audible range. 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 pull-up resi stors required for unused digital inputs which are meant to be positive.
tmc246 data sheet (v2.01 / sep. 14th, 2005) 17 copyright ? 2005, trinamic motion control gmbh & co kg slope control resistor the output-voltage slope of the fu ll bridge outputs can be controlled to reduce noise 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 fo r the fastest output-vol tage slope (respectively maximum output current). in most applicati ons 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 tr ansistors is fixed (corresponding to a 5k ? to 10k ? slope control resistor). for applications where elec tromagnetic 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, if only slow decay operation is used. please remark, that there is a trade off between reduced electromagnetic emissions (slow slope) and high efficiency because of low dynamic losses (fast slope). the following table and graph depict typical behavior m easured from 15% of output voltage to 85% of output voltage. however, the actual values m easured 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 18 copyright ? 2005, trinamic motion control gmbh & co kg absolute maximum ratings the maximum ratings may not be exceeded under any circumstances. symbol parameter min max unit v s supply voltage (a-type) 36 v v s supply voltage (non-a-type) 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 (short pulse) +/-7 a t a 85c 1500 t a 105c 1000 i oc output current (continuous, one bridge) t a 125c 800 ma v 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 automotive -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.
tmc246 data sheet (v2.01 / sep. 14th, 2005) 19 copyright ? 2005, trinamic motion control gmbh & co kg dc characteristics dc characteristics contain the spread of values guaranteed within the specified supply voltage and temperature range unless otherwise s pecified. typical characteristi cs 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 specified) symbol parameter conditions min typ max unit r out,sink r dson of sink-transistor t j = 25c v s 8v 0.13 0.19 ? r out,source r dson of source-transistor t j = 25c v s 8v 0.23 0.36 ? r out,sink r dson of sink-transistor max. t j =150c v s 8v 0.22 0.32 ? r out,source r dson of source-transistor max. t j =150c v s 8v 0.39 0.61 ? v 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 supply 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 ma 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, sck, csn, bl1, bl2, spe, ann) 100 300 500 mv v oh high output voltage (output sdo) -i oh = 1ma vcc ? 0.6 vcc ? 0.2 vcc v v 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 = 3.3v 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 0.1
tmc246 data sheet (v2.01 / sep. 14th, 2005) 20 copyright ? 2005, trinamic motion control gmbh & co kg (input enn) v ennh 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? internal ref. or 2v at ina / inb 315 350 385 mv v srs sra / srb overcurrent detection threshold 570 615 660 mv v sroffs sra / srb comparator offset voltage -10 0 10 mv r inab ina / inb input resistance vin 3 v 175 264 300 k ? ac characteristics ac characteristics contain the spread of val ues guaranteed within the specified supply voltage and temperature range unless otherwise s pecified. typical characteristi cs 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 1% 20 25 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 ? v o 15% to 85% i oxx = 800ma 125 ns t rs , t fs rise and fall time of outputs oxx with r slp = 50k ? v 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 21 copyright ? 2005, trinamic motion control gmbh & co kg thermal characteristics symbol parameter conditions typ unit r tha12 thermal resistance bridge 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 resistance 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
tmc246 data sheet (v2.01 / sep. 14th, 2005) 22 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 dsu sdi setup time 40 ns t dh sdi hold time 50 ns t d sdo delay time c l = 50pf 40 100 ns t zc csn high to sdo high impedance 50 ns t es enn to sck setup time 30 ns t pd csn high to output change delay 3 s sdo is tristated whenever e nn is inactive (high) or csn is inactive (high). 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 accepted, if their length is at least 12 bit. t 1 sdo sdi sck csn t es t 1 t 1 t cl t ch bit11 bit10 bit0 bit11 bit10 bit0 t d t zc t du t dh enn
tmc246 data sheet (v2.01 / sep. 14th, 2005) 23 copyright ? 2005, trinamic motion control gmbh & co kg esd protection please be aware, that the tmc246 is an esd s ensitive device due to integrated high performance mos transistors. esd sensitive device if the ics are manually handled before / during solder ing, special 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 i nputs and outputs withstand at least 1000v hbm.
tmc246 data sheet (v2.01 / sep. 14th, 2005) 24 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 following 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 depi cted circuit. a full scale sense voltage of 340mv is assumed. the circuit still takes advantage of complete ly 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 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 i spi is a trademark of motorola

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