vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 1 the sc1146 is patent pending pentium is a registered trademark of intel corporation block diagram features ? = allows use of small surface mount components ? = ultra fast transient recovery time ? = dramatic reduction of input ripple current and out- put ripple voltage ? = 5-bit programmable dac for the latest, lower output voltage microprocessors ? = wide, high frequency operating range ? = selectable 2, 3, 4 phase operation ? = +5 volt only operation eliminates the need for +12v supply ? = precision load current sharing,1%pwm match ? = selectable internal or external clock ? = soft start/uvlo/over current protection applications ? = high end servers and workstations ? = high current/ultra-fast transient microprocessors tel:805-498-2111 fax:805-498-3804 web:http:// www.semtech.com device (1) package temp. (t j ) sc1146csw.tr so-24 0 - 85c ordering information note: (1) only available in tape and reel packaging. a reel contains 1000 devices. description t he sc1146 is the late s t, high pe r f o r m an c e, m ulti- phase (pwm) controller designed for high power mi- croprocessors requiring ultra fast transient response. the sc1146 is programmable for the voltage range required by the latest microprocessors . utilizing a novel and unique design, the controller distributes the output load across (up to) four converter channels by digitally phase shifting the pwm outputs. this ap- proach greatly reduces the stress and heat on the out- put stage components while lowering input ripple cur- rent by as much as 80%. accurate current sharing among the four phases is achieved by precision design techniques and trimming of critical elements. the high speed transconductance error amplifier is ex- ternally initialized using a soft-start capacitor allowing the controller to ?wake-up? without overshoot, thus pro- tecting the low voltage microprocessor loads. the out- put drive voltage to the power mosfets is pro- grammable to minimize switching losses in the drive circuitry. the output voltage is digitally programmable by means of a 5 bit dac (new codes). a single resistor programs the master clock frequency (8mhz max) or the clock can be supplied by an external source where exact fre- quency control is desired. the number of operating phases is programmed independently of the external clock. the parts features under-voltage lock-out with hysteresis and over-current protection. pin configuration top view (24-pin soic)
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 2 the sc1146 is patent pending electrical characteristics unless otherwise noted: t a = 25 c, v cc 5v = 5v, v cc2 = 5v, 4-phase operation. parameter symbol conditions min typ max units supply voltage range v cc2 3.9 5.0 15.0 v uvlo range v cc5v 3.9 5.0 6.0 v uvlo hystersis v cc5v tbd mv supply voltage range v cc5v 4.5 5.0 5.5 v supply current v cc2 drv outputs open 10 ma supply current v cc5v v out = 2.00v, i o = 0 40 ma reference current pin voltage v ref iref = 250a 2.05 v vid0-4 clock select & divide v inl logic low 0.8 v select logic threshold v inh logic high 2 v vid0-4 clock select & divide i inl vid0-4 = 0v -20 a select input bias current i inh vid0-4 = 4.5v +50 a enable pin v inl .8 v v inh 2v maximum duty cycle d max fb = 0v 75 % drv0-3 output voltage v ol i sink = 1ma .3 v v oh i source = 1ma, pwrgood = v cc5v v cc2 -1 v drv0-3 source current i src v out = 2.00v 40 ma drv0-3 sink current i snk v out = 2.00v 20 ma absolute maximum ratings parameter symbol limits units v cc5v to gnd v cc5v -0.3 to + 12 v fbg to gnd fbg 1 v v cc2 to gnd v cc2 -0.3 to +20 v operating temperature range t a 0 to +70 c junction temperature range t j 0 to +125 c storage temperature range t stg -55 to +150 c thermal resistance junction to case jc 25 c/w thermal resistance junction to ambient ja 80 c/w lead temperature (soldering) 10 sec t lead 300 c
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 3 the sc1146 is patent pending o out i v ? ? in out v v ? ? electrical characteristics (cont.) unless otherwise noted: t a = 25 c, v cc5v = 5v, v cc2 = 5v, 4-phase operation. parameter symbol conditions min typ max units bgout voltage v bgout vid = 00000 tbd 1.30 tbd v bgout impedance r o_bg 3 k ? external clock freq. range f ext_ck .80 8.0 8.5 mhz oscillator frequency f osc iref = 250a 7.6 8.0 8.4 mhz internal clock freq. range f int_ck .80 8.0 8.5 mhz match drv0-3 ? = d duty cycle (avg) = 50% -1 +1 % pwm off time toff 25 % overcurrent comparator, comparator, common mode range occ_cmr 3 15 v oc+i/p bias current ib_oc+ vin = 5v +75 +250 oc-i/p bias current ib_oc- vin = 5v +75 +250 input offset voltage vos_occ vin = 5v 10 mv feedback input impedance ri_fb v o = 2.00v 12 ? duty cycle range d 0 75 % converter specifications, reference application circuit output accuracy over set range v out vid 0-4 = 0000-1111 v cc5v = 5.0v -1 +1 % load regulation v o = 2.000v i o = 3a - 20a .025 .05 %/a line regulation v cc5v = 5v, v o = 2.000v v in = 4-6v, (v in separated from vcc5v) i o = 5a , clk = external .15 %/v power good signal off leakage current i leakage_off pwrgood = logic high 2 a power good max sink current i sink_max pwrgood< = .8v 2 ma power good threshold p wrgood_t_lo vout = 1.300v - 1.950v + 100 mv voltage tolerance p wrgood_t_hi vout = 2.000v - 3.500v + 150 mv note: (1) this device is esd sensitive. use of standard esd handling precautions is required.
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 4 the sc1146 is patent pending note: (1) all logic inputs and outputs are open collector ttl compatible. pin description pin # pin name pin function 1v cc 5v supply voltage input (5v nominal) 2 divsel connect to gnd for four phase operation and to logic high for three phase operation. 3 clksel clock select: logic high selects internal clock. logic low selects external clock. 4 extclk external clock input. the output frequency is determined by (clock input freq.)/4. output freq.= (clock input)/4. pull up to vcc5v to select internal clock. 5r ref connects to external reference resistor. sets the operating frequency of the internal clock and the ramp time for the pwm. reference voltage at this pin is 2.05v. trimmed to set 250a at 8mhz. 6vid0 (1) programming input (lsb) 7vid1 (1) programming input 8vid2 (1) programming input 9vid3 (1) programming input 10 vid4 (1) programming input (msb) 11 oc+ over current comparator. non-inverting input. 12 oc- over current comparator. inverting input. 13 comp compensation pin. compensation is acheived by connecting a capacitor in series with a resistor between this pin and fbg. a 300k ohm resistor must also be directly connected between this pin and fbg. 14 fb feedback input connected to supply output. 15 bg out bandgap reference output. output resistance = 3kohm. must be bypassed with 4.7nf-100nf capacitor to fbg. this capacitor programs the soft start time. 16 fbg feedback ground. this pin must be connected to return side of output caps. this pin is not internally connected to gnd. 17 enable connects to 5v to enable. connect to gnd to disable entire device. 18 gnd ground pin 19 drv2 phase 2 output, output voltage range ~.3v - v cc2 - 1v. 20 drv0 phase 0 output, output voltage range ~.3v - v cc2 - 1v. 21 vcc2 supply voltage for the drv0-3, may be connected to +5v or +12v supply. there is no undervoltage lockout on this pin. 22 drv1 phase 1 output, output voltage range ~.3v - v cc2 - 1v. 23 drv3 phase 3 output, output voltage range ~.3v - v cc2 - 1v. 24 pwrgood power good should be pulled-up to 5v supply via a 3k - 10k resistor.
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 5 the sc1146 is patent pending output voltage unless specified: 0 = gnd; 1 = high (or floating). t a = 25 c, v cc5v = 5v, v cc2 = 5v, 4-phase operation. v cccore vid4 vid3 vid2 vid1 vid0 (vdc) 1 1 1 1 1 output off 11 1 1 01.1 1 1 1 0 1 1.125 11 1 0 01.15 1 1 0 1 1 1.175 11 0 1 01.2 1 1 0 0 1 1.225 1 1 0 0 0 1.250 1 0 1 1 1 1.275 10 1 1 01.3 1 0 1 0 1 1.325 10 1 0 01.35 1 0 0 1 1 1.375 10 0 1 01.4 1 0 0 0 1 1.425 10 0 0 01.45 0 1 1 1 1 1.475 01 1 1 01.5 0 1 1 0 1 1.525 01 1 0 01.55 0 1 0 1 1 1.575 01 0 1 01.6 0 1 0 0 1 1.625 01 0 0 01.65 0 0 1 1 1 1.675 00 1 1 01.7 0 0 1 0 1 1.725 00 1 0 01.75 0 0 0 1 1 1.775 00 0 1 01.8 0 0 0 0 1 1.825 00 0 0 01.85
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 6 the sc1146 is patent pending evaluation board schematic en en vout en smod +12v vout ensyn power good sel r22 10k r20 r6 10k 10 r1 open r24 r5 10k tbd r18 100 r19 0 r17 0 r2 0 r23 0 r3 0 r12 0 r14 0 r16 tbd r27 0 r26 0 r10 22 r9 22 r11 22 r13 r7 10k 22u,10v c20 22u,10v c21 1 r21 22u,10v c24 2.2 r25 j1 input 1 2 3 4 5 6 s1 vout/clk switch 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 22u,10v c17 22u,10v c15 1u,16v c12 22u,10v c10 u5 sc1405b 13 4 3 2 1 14 6 5 10 7 9 11 12 8 tg co gnd en ovp_s bst delay_c s_mod pgnd prdy bg dsps_dr drn vcc 10u,16v c19 10u,16v c36 u3 sc1405b 13 4 3 2 1 14 6 5 10 7 9 11 12 8 tg co gnd en ovp_s bst delay_c s_mod pgnd prdy bg dsps_dr drn vcc 1u,16v c11 d6 30bq015 d7 30bq015 d1 ss12 d3 ss12 d4 ss12 22u,10v c25 22u,10v c30 22u,10v c29 fdb7030 q4 fdb7030 q6 fdb7030 q8 d2 ss12 u1 sc1405b 13 4 3 2 1 14 6 5 10 7 9 11 12 8 tg co gnd en ovp_s bst delay_c s_mod pgnd prdy bg dsps_dr drn vcc u4 sc1405b 13 4 3 2 1 14 6 5 10 7 9 11 12 8 tg co gnd en ovp_s bst delay_c s_mod pgnd prdy bg dsps_dr drn vcc 22u,10v c33 22u,10v c34 22u,10v c6 22u,10v c1 22u,10v c38 r4 10k d5 30bq015 fdb7030 q2 fdp6035 q1 10u,16v c28 fdp6035 q3 fdp6035 q5 fdp6035 q7 pid1103-1u l1 pid1103-1u l3 pid1103-1u l5 c43 .001 .1u c42 .1u c40 .1u c22 10uf,6.3v c8 .01 c45 47pf c44 47pf c16 47pf c37 .1 c46 47pf c26 330uf,16v c13 .1u c7 .1u c14 .1u c23 .1u c32 .1u c41 .1 c48 .1u c2 .1u c9 .1u c3 .1u c4 .1u c5 .1u c31 1000uf,6.3 c39 .1u c18 .1u c35 .1u c47 .1u c27 0 r28 0 r29 0 r30 0 r31 .1u c49 22 r8 3k r32 10k r33 .1u c50 1000uf,6.3 c51 d8 30bq015 pid1103-1u l7 jmp1 jmp2 sc1146 u2 12 9 2 3 1 13 7 5 6 11 14 4 10 15 16 17 18 19 20 21 22 23 24 8 oc- vid3 divsel clksel 5v comp vid1 rref vid0 oc+ fb extclk vid4 bgout fbg enable gnd drv2 drv0 vcc2 drv1 drv3 pwrgood vid2 open r15 long pcb trace * * r26 and r27 set the overvoltage trip point. c48 sets the time constant. r27=0,r26=open to disable ovp_s. by jumpering jmp1, all sc1405's are enabled and disabled together with sc1144. three of the sc1405's can be directly controlled by separating the two enables. (power saving mode) shipped with ovp_s disabled freq. set by r22 freq.=(8.2k/r22)*2mhz per phase
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 7 the sc1146 is patent pending bill of material item qty reference value manufacturer 1 9 c2,c4,c11,c19,c20,c28,c29,c37,c39 1u,10v x7r, avx (818)883-7606 2 1 c3 10uf, 6.3v al. elec.,murata 3 9 c5,c12,c14,c17,c18,c21,c22,c26,c27 22u, 10v murata (512)250-5082 pn #grm235y5v226z010 4 5 c6,c7,c15,c24,c32 1uf, 16v murata,al. elec. 5 1 c8 330uf, 16v nichicon 6 3 c16,c25,c33 10u, 16v murata 7 1 c40 .01u murata 8 1 c42 .022 any 9 2 c45,c49 .01 murata,x7r 10 1 c46 .001 murata 11 4 c50,c51,c52,c53 1nf any 12 1 c54 1000uf murata,al. elec. 13 8 d1,d2,d3,d4, d5,d7,d9,d11 ss12(1a) ss32 (3a) general instruments general instruments 14 1 j1 input 15 4 l1,l2,l3,l4 .6uh,12a falco (305)662-7276 pn #t02508 16 4 q1,q4,q7,q10 ir7811 int. rectifier 17 4 q3,q6,q9,q12 ir3101d2 (alter.)fdb7030bl int. rectifier fairchild semiconductors 18 1 r1 10 dale,any 19 9 r2,r10,c13,r14,r17,c23,r33,c34,c43 0 any 20 4 r4,r12,r16,r23 1.5 (or zero) any 21 4 r5,r6,r7,r38 10k any 22 4 r8,r9,r11,r13 22 any 23 1 r18 sel any 23 1 r19 100 any 24 1 r20 2.2k any 25 1 r22 15k any 26 1 r24 300k any 27 5 r25,r40,r41,r42,r43 2.2 any 28 1 r26 open any 29 4 r27,r28,r29,r30 51, 1/4w, 1206, 10k dale 30 6 r31,r32,r34,r35,r36,r37 tbd(used at light load, contact factory) any 31 1 s1 vout/clk switch c&k (800)cal-swch 32 4 u1,u3,u4,u5 sc1405b/sc1405ts semtech (805)498-2111 33 1 u2 sc1146csw semtech (805)498-2111 34 1 u6 lm358 any unless otherwise noted, all resistors are 1/10w, 5%, 0805 and all capacitors are 20%, 50v, 0805.
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 8 the sc1146 is patent pending functional description the sc1146 is a programmable, high performance, multi-phase controller designed for the most demand- ing dc/dc converter applications in which transient response, space, input ripple current and component form factor and cost are paramount. the sc1146 is configured to operate with external mosfet drivers, such as the sc1405, in high efficiency synchronous applications (see evaluation board schematic). the sc1146 based dc/dc converter consists of four buck converter controllers integrated and synchro- nized. the high clock frequency allows for smaller in- ductor values and miniature surface mount, low induc- tance output capacitors. since each stage has ? the output current, the conduction losses in each stage is reduced by a factor of 1/16. precision active trimming ensures 1% matching of duty cycles among phases, thus ensuring the heat and component stress is shared equally. the sc1146 may also be configured in asyn- chronous mode by using buffer transistors. decoder/bias generator/pwm controller the 8 mhz clock is divided down to 2 mhz for four phase operation by the clock decoder. the start of the output pulses are time shifted 90 degrees by the de- coder with respect to each other. the bias generator generates the ramps to each phase by a precision trimmed current source and on-chip capacitors. the decoder, which is synchronized to the bias generator via the master clock, phase shifts the ramps and en- ables the pwm controller sequentially. a resistor from r ref pin to fbg programs the frequency and ramp time. clock freq = (8.2k/rref) *8mhz the ramps are then compared to the error amplifier out- put at the high speed pwm comparator inputs. the con- troller outputs are buffered versions of the comparator outputs. error amplifier at the heart of the controller is an ultra-fast, transcon- ductance error amplifier. since the output inductor val- ues can be selected to be a minimum, usually less than a micro-henry, the delays due to inductor ramp time are minimized during transient load recovery. the higher frequency of operation also allows use of much smaller capacitance on the output. this means that the dc/dc converter output capacitors ?hold time? is less. the error amplifier must therefore respond extremely fast ?recover the fort? after a transient. the sc1146 error amplifier recovers to its normal duty cycle after applica- tion of a full load transient within 2 usec maximum, (largely dependant on supply quality) and usually within 1usec. this minimizes undershoot and overshoot during application of a transient. theory of operation fig. 2: the four gate drives firing 90 out of phase. v out = 1.0v, i out = 10a,vcc2=12v, asynchronous operation. fig. 1: v out ripple, v out = 1.0v, i out = 30a
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 9 the sc1146 is patent pending the error amplifier has two inverting inputs, one for the high range, (vid4 set to logic high) and one input for the low range. the effective gain of the error ampli- fier stays constant in both ranges keeping the loop gain constant regardless of output voltage range. bandgap reference/soft start the precision internal bandgap reference provides a stable, temperature compensated 2.05 v reference for the error amplifier?s non-inverting input, the dac ref for the vid digital to analog converter, the under-voltage lock-out circuitry as well as the reference for the bias generator current sources. the error amplifiers non- inverting input is connected to the bandgap reference through a 3kohm resistor, which is also externally con- nected to a soft-start capacitor via the bg out pin. upon application of power, the non-inverting input of the er- ror amplifier is held low for a short time, set by the rc product of the soft-start capacitor and 3kohm, allowing for the decoder and pwm controller to settle. this pre- vents any harmful output voltage overshoots upon start up or after a converter shut-down (as a result of over- current or the enable pin pulled low). the non-inverting input then ramps up according to the rc time constant allowing gradual rise of output voltage. over-current comparator the sc1146 has an internal over-current comparator designed to sense current in the input supply path. the comparator inputs have a high common voltage range thus allowing operation under all possible volt- age/current combinations. the output of the compara- tor pulls the bg out (soft start) pin low thus disabling the error amplifier and causing the pwm outputs to enter minimum duty cycle mode, regulating the output at a minimum voltage. a current sense trace may be used as the current sense resistor. this will utilize the trace as input filter inductor, thus preventing conducted emissions to input supply. for details of programming the overcurrent comparator, refer to sc1144-evb user manual. sc1146 special features: the sc1146 is a special version of the original sc1144, 4-phase pwm controller, with the latest vrm9.0 vid codes which allow programming lower output voltages required by the latest microprocessors. also a +12v supply is no longer required. the v cc2 and pwrgood pins can be connected to vcc5v. this eases the connection to ?5v-only? mosfet drivers, such as the sc1405. the drvs will swing to vcc5v, eliminating the need for +12v to +5v level shifting. there is no under-voltage lockout on v cc2 . error amplifier cont. fig. 3: transient response, top trace, current sense 8a/div @ 30a/usec. bottom trace, v out . fig. 4: transient response, top trace, gate drive bottom trace, transient current 16a/div @ 30a/usec.
vrm9.0 programmable, multi-phase, high performance pwm controller sc1146 ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 july 25, 2000 10 the sc1146 is patent pending outline drawing - so-24 jedec ms-013ad b17104b an evaluation board is available which may be ordered directly from the factory. sc1146/1405evb is a dc/dc converter utilizing the sc1146 four-phase controller in a high current synchronous application. the evaluation board is intended as a guideline for board design, layout and to assess key performance parameters, such as tran- sient response, thermal stress management and input and output ripple considerations. the sc1146evb includes a dip switch for mode/voltage selection as well as qualified selection of components for the sc1146 operation. the sc1144evb user manual contains useful general applications information applicable to sc1146 and may be accessed from our website at www.semtech.com. ecn00-1215
|
