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description the a4915 is designed for pulse width modulated (pwm) current control of 3-phase brushless dc motors. the a4915 is capable of high current gate drive for 6 all n-channel power mosfets. an internal charge pump ensures gate drive down to 7 v supply and provides limited gate drive down to 5 v. a bootstrap capacitor is used to generate a supply voltage greater than the source voltage of the high side mosfet, required for n-channel mosfets. internal synchronous rectification control circuitry is provided to improve power dissipation in the external mosfets during pwm operation. internal circuit protection includes latched thermal shutdown, dead time protection, and undervoltage lockout. special power up sequencing is not required. the a4915 is supplied in a 28-pin tssop with an exposed thermal pad (suffix lp) and a 28-contact 5 5 mm qfn with an exposed thermal pad (suffix et). these packages are lead (pd) free, with 100% matte-tin leadframe plating. a4915-ds, rev. 1 features and benefits ? 5 to 50 v supply voltage ? latched tsd with fault output ? drives six n-channel high current mosfets ? internally controlled synchronous rectification ? speed voltage input enables internal pwm duty cycle control of full bridge ? center aligned pwm ? internal uvlo and crossover current protection ? hall switch inputs ? adjustable dead time protection ? low power sleep mode for battery-powered applications 3-phase mosfet driver packages: functional block diagram not to scale a4915 28-contact qfn 5 mm 5 mm 0.90 mm (et package) 28-pin tssop with exposed thermal pad (lp package) charge pump regulator comm logic dir hb hc ha braken enable gla gha vbb cp1 cp2 control logic gnd v in sa ghb sb glb ghc sc glc speed 0.47 f r gate r gate ca c boota to phase b to phase c lss cb cc bootstrap monitor vreg vreg creg cvbb1 cvbb2 ha hb hc r1 r2 r3 phase a one of three phases shown high side driver low side driver vdd tdead r dead 47 v tvs voltage to duty osc fault v reset cvdd1 vdd vdd a4915 vdd
3-phase mosfet driver a4915 2 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com absolute maximum ratings characteristic symbol notes rating unit load supply voltage v bb ?0.3 to 50 v logic supply voltage v dd ?0.3 to 6 v vreg pin v reg ?0.3 to 16 v cp1 pin v cp1 ?0.3 to 16 v cp2 pin v cp2 v cp1 ? 0.3 to v reg + 0.3 v logic inputs v i ?0.3 to 6 v hall inputs v hx ?0.3 to 6 v logic outputs v o ?0.3 to 6 v speed input v speed ?0.3 to 6 v ca, cb, and cc pins v cx ?0.3 to v reg + 50 v gha, ghb, and ghc pins v ghx v cx ? 16 to v cx + 0.3 v sa, sb, and sc pins v sx v cx ? 16 to v cx + 0.3 v gla, glb, glc pins v glx v reg ? 16 to 18 v maximum continuous junction temperature t j (max) 150 c storage temperature range t stg ?55 to 150 c operating ambient temperature range t a ?20 to 105 c thermal characteristics may require derating at maximum conditions, see application information characteristic symbol test conditions* value unit package thermal resistance r ja package et, on 4-layer pcb based on jedec standard 32 oc/w package lp, on 4-layer pcb based on jedec standard 28 oc/w *additional thermal information available on the allegro website. selection guide part number package packing* A4915METTR-T 28-contact qfn with exposed thermal pad 1500 pieces per 7-in. reel a4915mlptr-t 28-pin tssop with exposed thermal pad 4000 pieces per 13-in. reel
3-phase mosfet driver a4915 3 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com terminal list table name function number name function number et lp et lp vbb supply voltage 1 18 sc high-side source connection 15 4 speed reference voltage input 2 19 cc bootstrap output phase c 16 5 tdead terminal for dead time setting 3 20 glb low-side gate drive 17 6 vdd logic supply input 4 21 ghb high-side gate drive 18 7 fault fault output 5 22 sb high-side source connection 19 8 enable logic input, pwm control 6 23 cb bootstrap output phase b 20 9 dir logic input, motor direction 7 24 gla low-side gate drive 21 10 braken logic input, motor brake (active low) 8 25 gha high-side gate drive 22 11 ha hall input phase a 9 26 sa high-side source connection 23 12 hb hall input phase b 10 27 ca bootstrap output phase a 24 13 hc hall input phase c 11 28 vreg gate drive supply output 25 14 lss sense input 12 1 cp2 charge pump capacitor terminal 26 15 glc low-side gate drive 13 2 cp1 charge pump capacitor terminal 27 16 ghc high-side gate drive 14 3 gnd ground 28 17 pad exposed pad for enhanced thermal dissipation ? ? pad 21 20 19 18 17 16 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 gnd cp1 cp2 vreg ca sa gha braken ha hb hc lss glc ghc gla cb sb ghb glb cc sc vbb speed tdead vdd fault enable dir lss glc ghc sc cc glb ghb sb cb gla gha sa ca vreg hc hb ha braken dir enable fault vdd tdead speed vbb gnd cp1 cp2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 pad pin-out diagrams et package lp package
3-phase mosfet driver a4915 4 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com electrical characteristics valid at t a = 25c, v bb = 24 v; unless otherwise specified characteristic symbol test conditions min. typ. max. unit supply and reference operating voltage range v bb operating, outputs active 5.0 ? 50 v motor supply current i bb f enb = 30 khz, c load = 10 nf ? 10 20 ma f pwm 20 khz, c load = 10 nf ? 12 24 ma v reg = 13 v, outputs disabled ? 3 3.5 ma sleep mode ? ? 1 a bootstrap diode forward voltage v fboot i d = 10 ma 0.4 0.7 1.0 v i d = 100 ma 1.5 2.2 2.8 v bootstrap diode current limit v dboot 250 500 750 ma vdd input voltage v dd 3 ? 5.5 v vdd input current i ddq enable = high, outputs disabled ? 6 10 ma i dds sleep mode ? ? 10 a enable input current sleep mode i enb(slp) enable = low for longer than t sleep , speed = high ??1 a speed input current sleep mode i speed(slp) enable = high, speed = low for longer than t sleep ??1 a braken input current sleep mode i brake(slp) enable = low for longer than t sleep ??1 a dir input current sleep mode i dir(slp) enable = low for longer than t sleep ??1 a enable input frequency range f enb v speed = v dd 1 ? 100 khz internal pwm frequency f pwm v enable = v dd 14 20 26 khz speed input voltage range v speed 0?v dd v speed disable voltage v speed(d) measured as v speed / v dd , duty cycle = 0% 10 15 20 % speed enable voltage* v speed(e) measured as v speed / v dd , duty cycle = 100% 79 82 86 % speed bias current i speed(bias) v speed = v dd = 5 v ?25 0 25 a vreg output voltage v reg v bb = 9 v 11.8 13 13.75 v v bb = 7.5 v 11.5 13 13.75 v v bb = 6 v 2 v bb ? 3.5 v ??v v bb = 5.5 v 8.0 9.5 ? v protection thermal shutdown temperature t tsd fault rising 155 170 185 c vreg undervoltage v regon v reg rising 7.0 7.8 8.6 v v regoff v reg falling 6.39 7.1 7.81 v vreg undervoltage hysteresis v reghys ? 700 ? mv continued on the next page?
3-phase mosfet driver a4915 5 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com protection (continued) bootstrap undervoltage v bootuv measured as a percentage of v reg 55 ? 65 % bootstrap undervoltage hysteresis v bootuvhys measured as a percentage of v reg ?20? % vdd undervoltage v dduv v dd rising ? 2.75 2.95 v v dd falling 2.45 2.6 ? v vdd undervoltage hysteresis v dduvhys 50 100 150 mv sleep wake-up delay t wake ??3ms gate drive high-side gate drive output v ghx c bootx fully charged, c load = 10 nf v cx ? 0.2 ? ? v i ghx < 10 a??v sx + 0.3 v low-side gate drive output v glx v reg = 13 v, c load = 10 nf v reg ? 0.2 ? ? v i glx < 10 a ? ? 0.3 v gate drive pull-up resistance r ghx(on)up t j = 25c, i ghx = ?150 ma 6 9 12 t j = 125c, i ghx = ?150 ma ? 17 ? gate drive pull-down resistance r glx(on)dn t j = 25c, i glx = ?150 ma 2.4 3.5 4.6 t j = 125c, i glx = ?150 ma ? 5 ? ghx passive pull-down r ghx(ppd) v ghx ? v sx < 0.3 v ? 5000 ? glx passive pull-down r glx(ppd) v glx ? v lss < 0.3 v ? 5000 ? output switching time t rgx 20% to 80%, c load = 10 nf ? 200 ? ns t fgx 80% to 20%, c load = 10 nf ? 150 ? ns dead time t dead time delay measured from turn-off to turn-on tdead tied to gnd 10 ? ? ns r tdead = 12 k ? 150 ? ns r tdead = 64 k 800 925 1050 ns r tdead = 220 k ? 2.9 ? s logic i/o logic input voltage v in(h) braken, dir, enable, ha, hb, and hc pins 0.7 v dd ??v v in(l) ? ? 0.3 v dd v logic input current i in(h) v in = high ? 10 ? a i in(l) v in = low, enable = low ?1 0 1 a fault output voltage v fault no fault present, i sink = 1ma ? ? 0.2 v enable and speed sleep timer t sleep enable = low, speed = high 1 2 3 ms enable = high, speed = low 1 2 3 ms electrical characteristics (continued) valid at t a = 25c, v bb = 24 v; unless otherwise specified characteristic symbol test conditions min. typ. max. unit continued on the next page?
3-phase mosfet driver a4915 6 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com electrical characteristics (continued) valid at t a = 25c, v bb = 24 v; unless otherwise specified characteristic symbol test conditions min. typ. max. unit logic i/o (continued) speed sleep threshold v speedslp th speed = low for longer than t sleep ? ? 295 mv fault latch reset voltage v reset fault is present, outputs latched ? ? 0.8 v fault latch reset pulse time t fault fault is present, outputs latched 12 ? ? s hall input pull-up resistor r hx(pu) hx pins, v in = 0 v ? 100 ? k hall input current i hall hx pins, v in = 5 v ? 0 1 a logic input pull-down resistor r in(pd) enable, dir, braken, v in = 5 v ? 50 ? k login input current sleep mode i in(slp) enable, dir, braken ? ? 1 a propagation delay t pd(on) dir or braken input to output change, c load = 0 nf ? ? 1200 ns enable input to output change, c load = 0 nf ? ? 900 ns t pd(off) dir or braken input to output change, c load = 0 nf ? ? 1200 ns enable input to output change, c load = 0 nf ? ? 900 ns input pin glitch reject t glitch enable ? ? 900 ns dir, braken ? ? 1000 ns *output duty cycle limited by t dead .
3-phase mosfet driver a4915 7 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com functional description basic operation the a4915 is a 3-phase mosfet driver intended to drive high current mosfets. it is designed for use in battery operated equipment where low-voltage operation is critical. the a4915 also features a low current sleep mode which disables the device and draws minimum supply current. the a4915 is capable of driving 6 n-channel mosfets. commutation logic includes enable, direction, and brake modes for external pwm control. a speed input is provided which allows an external source to pwm the bridge at 30 khz typical. the pwm duty cycle is controlled by applying an analog voltage to the speed pin from 0 v to v dd . pin descriptions dir the direction pin is used to change the commutation direc- tion of the 3 bridges. refer to table 1 for phase commutation information. enable the enable input terminal allows external pwm control. setting enable high turns on the selected sink-source pair, and setting it low switches off the appropriate drivers and the load current decays. if external pwm is used, the speed pin must be tied to vdd. when the enable input is held low for longer than t sleep the a4915 turns off all internal circuitry and draws minimum current from the supply. when coming out of sleep allow 3 ms for the charge pump regulator to stabilize. speed the duty cycle of the internally generated carrier fre- quency is controlled by applying a dc voltage on the speed input. a plot showing the relationship of speed to duty cycle is shown in figure 1. when speed is pulled directly to vdd the internal carrier is disabled and the enable input can be used to pwm the bridge. when v speed < v speed(d) the output is guar- anteed to be 0%. when v speed > v speed(e) the output is guaran- teed to be 100%. braken brake mode turns all three sink drivers on and effec- tively shorts out the motor generated bemf. the braken input overrides the enable and speed inputs except when in sleep mode. refer to table 2 for the logic truth table. in order to comply with failure mode effects and analysis (fmea), the brake func- tion is normally active (logic low). if the braken pin on the device is open due to some failure of solder joint or microproces- sor failure, the device will automatically implement brake mode, preventing the motor from turning or pumping up the supply. applying logic high to the braken terminal deactivates brake mode and allows normal operation. care must be taken when applying the brake command because large currents can be generated. the user must ensure that the maximum ratings of the mosfets are not exceeded under worst table 1. commutation table ha hb hc dir gla glb glc gha ghb ghc sa sb sc 1 1 0 1 1 0 0 1 1 0 0 high ? low 2 1 0 0 1 0 0 1 0 1 0 ? high low 3 1 1 0 1 1 0 0 0 1 0 low high ? 4 0 1 0 1 1 0 0 0 0 1 low ? high 5 0 1 1 1 0 1 0 0 0 1 ? low high 6 0 0 1 1 0 1 0 1 0 0 high low ? 1 1 0 1 0 1 0 0 0 0 1 low ? high 2 1 0 0 0 0 1 0 0 0 1 ? low high 3 1 1 0 0 0 1 0 1 0 0 high low ? 4 0 1 0 0 0 0 1 1 0 0 high ? low 5 0 1 1 0 0 0 1 0 1 0 ? high low 6 0 0 1 0 1 0 0 0 1 0 low high ? hall fault 111x000000??? hall fault 000x000000???
3-phase mosfet driver a4915 8 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com case braking conditions. maximum motor current during brake mode can be approximated by: i braken = v bemf / r l where v bemf is the voltage generated by the motor and r l is the resistance of the phase winding. vreg a regulated voltage output that is used to supply the low-side gate drivers and to charge the bootstrap capacitors. fault the fault output is active high. under normal operation the open drain output pulls the fault output to ground. when a fault occurs the open drain output is released, and the fault output is then pulled to a logic high through a connected external passive pullup resistor. fault conditions are shown in table 3. the presence of an invalid hall combination is referred to as a hall fault . invalid hall combinations are documented in table 1. when a hall fault is present, the outputs are disabled. invalid hall faults are not latched, and do not affect the state of the fault pin. latched faults that result in disabled outputs can be reset in a number of ways: ? a uvlo on vdd will serve as a reset ? if the device is put into sleep mode the latch is reset ? a microprocessor can create a reset on the fault pin directly by forcing v reset on the fault pin when a fault is active for longer than t fault (that is, when the outputs are latched) lss the lss terminal is the low-side drain connection for the mosfet. if an external pwm current control loop is used, a low table 2. input logic truth table inputs mode of operation enable speed braken low high high pwm chop slow decay synchronous rectification (center aligned) low high low brake mode ? all low-side gates on high high high selected drivers on b high high low brake mode ? all low-side gates on high v dd v speed(e) to v dd v speed(d) high pwm chop slow decay synchronous rectification (center aligned) c high > v dd v speed(e) high selected drivers on b high < v dd v speed(d) high pwm chop slow decay synchronous rectification (center aligned) low longer than t sleep high x a sleep mode ? coast high low longer than t sleep x a sleep mode ? coast a x = don?t care. b maximum and minium duty cycle limited by boot capacitor charge management. c internal pwm active. 0 10 20 30 40 50 60 70 80 90 100 10 20 30 40 50 60 70 80 90 100 t on /t (%) v speed /vdd (%) figure 1. speed in relation to duty cycle table 3. fault conditions event fault pin outputs latched tsd high disabled yes sleep high disabled no uvlo vreg/vdd high disabled no invalid hall low disabled no
3-phase mosfet driver a4915 9 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com value sense resistor can be placed from lss to ground for current sensing purposes, otherwise lss should be connected directly to power ground. ca, cb, cc high-side connections for the bootstrap capacitors (cbootx) and positive supply for high-side gate drive. gha, ghb, ghc high-side gate drive outputs for n-channel mosfets. sa, sb, sc motor phase connections, serve as the negative sup- plies for the high-side gate drive. gla, glb, glc low-side gate drive outputs for n-channel mosfets. cp1, cp2 connections for the charge pump switching capacitor. typical capacitance should be 0.47 f. ha, hb, hc hall input connections from hall switches at the motor. thermal shutdown if the die temperature exceeds t tsd , the fault output is turned off and the outputs are disabled. thermal shutdown is a latched fault. dead time to prevent cross-conduction (shoot through) in any phase of the bridge, it is necessary to have a dead time, t dead , between a high- or low-side turn-off and the next complementary turn-on event. the dead time for all three phases is set by a single dead time resistor (r dead ) between the tdead pin and ground. for r dead values between 12 and 220 k , at 25c the nominal value of t dead in ns can be approximated by: t dead = 40 + (1.28 ?2 r dead ) current, i dead , can be calculated by: i dead = 1.2 / r dead as values for r increase, current offsets and resistor mismatch cause the error terms to increase. figure 2 shows the typical expected error for a given r dead value. sleep mode the a4915 has a low-current sleep mode to limit current draw on the battery. when in low-current sleep mode (when enable = low for longer than t sleep and speed = high), current into vbb and vdd is less than 1 a. when enable is held low for longer than t sleep and the speed input is held high, the pull-up resistors on the hall inputs and the pull-down resistor on the braken pin are open-circuited to minimize current draw into logic input terminals. only the condition where speed = high and enable = low for longer than t sleep results in low current on logic input terminals. center aligned pwm the a4915 features center aligned pwm, which improves power dissipation and helps reduce emi. during an off-time triggered by either an internal pwm or by an external enable chop command, current recirculation will be in either the high- side fets or the low-side fets, depending on the state of an internal latch. on each bridge enable command, the latch is reset and the current recirculation shifts from high-side recirculation to low-side recirculation. 0 500 1000 1500 2000 2500 3000 3500 4000 10 30 50 70 90 110 130 150 170 190 210 230 250 dead time (ns) r dead (k ) typical minimum maximum figure 2. r dead versus dead time error
3-phase mosfet driver a4915 10 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com this method of recirculation shifts 50% of the power to the high-side drivers during the off-time, reducing the power dissipa- tion in the sink drivers. reducing the overall temperature of the output drivers by sharing power between the 6 fets improves system efficiency and battery life. internal/external pwm the a4915 can be pulse width modulated (pwm) to control cur- rent. there are two methods by which pwm can be applied to the device. ? external pwm. this method requires a pwm signal be applied to the enable pin. when the speed pin is tied directly to vdd, the enable pin can be chopped from 0 to 100%. if the enable input is held low for more than sleep timer, t sleep , the device enters low current sleep mode. ? internal pwm. this method uses the internally generated pwm, which is controlled by applying a dc voltage to the speed pin. when the enable pin is tied directly to vdd, the speed can be controlled from 0 to 100%. see the speed pin description for further information. for complete description of all operating conditions, see table 2. synchronous rectification when a pwm off-time cycle is triggered by an enable chop command or by an internal pwm off-time, load current recircu- lates. the a4915 synchronous rectification feature will turn on the appropriate mosfets during the off-time and effectively short out the body diodes with the low r sd(on) driver. this will lower power dissipation significantly and eliminates the need for external schottky diodes. charge pump regulator the gate drives for the low-side mosfets and the bootstrap charge for the high-side drivers is accomplished by the charge pump regulator. for v bb above 16 v, the regulator acts as a linear regulator. below 16 v, the regulated supply is maintained by a charge pump boost converter that requires a pump capacitor between cp1 and cp2. the regulated voltage vreg is decoupled on the vreg termi- nal. the decoupling capacitance is based on the bootstrap capaci- tor which is dependent on the mosfet selection. refer to the application information section for details on correct sizing of vreg and bootstrap capacitors. gate drive and rgate the gate drive for the external mosfets is capable of providing the large current transients needed to quickly charge and dis- charge the gate capacitance to maintain fast switching speeds and minimal power dissipation. the low-side driver current is sourced by the capacitor on the vreg terminal. the high-side gate drive current is supplied by the respective bootstrap capacitance con- nected between the cx and sx terminals. the charge and dis- charge of the gate can be controlled by using an external resistor (r gate ) in series with the gate. bootstrap charge management in order to protect the external mosfets from insufficient gate drive, it is important that the bootstrap capacitor voltage be moni- tored. before a high-side switch is allowed to turn on, it must have sufficient charge on the bootstrap capacitor. if the voltage on the bootstrap capacitor is below the turn-on voltage limit, the a4915 will attempt to charge the bootstrap capacitor by turning on the associated low-side driver. the bootstrap monitor stays active during the duration of the switch on-time. if the voltage falls out of compliance at any time when the high-side driver is enabled, the driver is disabled and the low-side switch is acti- vated to charge the bootstrap capacitor. during normal operation and in conditions where the pwm duty cycle creates short off-times, the low-side switch may be activated more often to keep sufficient charge on the bootstrap capacitor. proper sizing of the bootstrap and vreg capacitors is critical to being able to maintain effective gate drive. refer to the application information section for details on correct sizing of vreg and bootstrap capacitors.
3-phase mosfet driver a4915 11 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com application information bootstrap capacitor selection in order to properly size the capacitor cboot, the total gate charge must be known. too large a bootstrap capacitor and the charge time will be long, resulting in maximum duty cycle limita- tion. too small a capacitor and the voltage ripple will be large when charging the gate. size the cboot capacitor such that the charge, q boot , is 20 times larger than the required charge for the gate of the mosfet, q gate : c boot = ( q gate 20) / v boot where v boot is the voltage across the bootstrap capacitor. the voltage drop across the bootstrap capacitor as the mosfet gate is being charged, v, can be approximated by: v = q gate / c boot for the bootstrap capacitor, a ceramic type rated at 16 v or larger should be used. vreg capacitor selection vreg is responsible for providing all the gate charge for the low side mosfets and for providing all the charge current for the three bootstrap capacitors. for these purposes, the vreg capaci- tor, c reg , should be 20 times the value of c boot : c reg = 20 c boot layout recommendations careful consideration must be given to pcb layout when design- ing high frequency, fast-switching, high-current circuits (refer to figures 3 and 4): ? the a4915 ground, gnd, and the high-current return of the ex- ternal mosfets should return separately to the negative side of the motor supply filtering capacitor. this minimizes the effect of switching noise on the a4915. ? the exposed thermal pad should be connected to gnd. ? minimize stray inductance by using short, wide copper traces at the drain and source terminals of all power mosfets. this includes motor lead connections, the input power bus, and the common source of the low-side power mosfets. this mini- mizes voltages induced by fast switching of large load currents. ? consider the use of small (100 nf) ceramic decoupling capaci- tors across the source and drain of the power mosfets, to limit fast transient voltage spikes caused by inductance in the traces. ? keep the gate discharge return connections sx and lss as short as possible. any inductance on these traces causes negative transitions on the corresponding a4915 terminals, which may exceed the absolute maximum ratings. if this is likely, con- sider the use of clamping diodes to limit the negative excursion on these terminals with respect to gnd. ? supply decoupling for vbb, vreg, and vdd should be con- nected independently, close to the gnd terminal. the decou- pling capacitors should also be connected as close as possible to the relevant supply terminal. ? gate charge drive paths and gate discharge return paths may carry large transient current pulses. therefore the traces from ghx, glx, sx (x = a, b, or c) and lss should be as short as possible to reduce the inductance of the trace. ? provide an independent connection from lss to the common point of the power bridge. this can be the negative side of the motor supply filtering capacitor or one end of a sense resistor. it is not recommended to connect lss directly to the gnd termi- nal, as this may increase the noise at the digital inputs.
3-phase mosfet driver a4915 12 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com r10 q4 r4 r8 q2 r2 r11 q5 r5 r9 q3 r3 r12 q6 r6 vbb vbb lss phase b phase a c7 vdd c4 r24 r15 c5 d1 c1 c2 gnd gnd gnd gnd phase c c8 c6 vbb c9 c10 r7 q1 r1 et package typical pcb layout figure 3. typical application information for et package et package schematic corresponding to typical pcb layout pcb thermal vias trace (2 oz.) signal (1 oz.) ground (1 oz.) thermal (2 oz.) solder a4915 braken ha hb hc lss glc ghc cp1 ca sa gha cp2 vreg gnd c4 c5 r24 r15 a4915 dir enable fault vdd vdd tdead speed vbb pad q5 r5 r11 outb c9 q2 r2 r8 glb ghb sb cb q6 r6 r12 outc c10 q3 r3 r9 sc cc q4 r4 r10 outa c8 q1 r1 r7 gla vbb c1 c2
3-phase mosfet driver a4915 13 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com phase c c8 c6 c9 c10 r7 q1 r1 r10 q4 r4 r8 q2 r2 r11 q5 r5 r9 q3 r3 r12 q6 r6 vbb lss phase b phase a c7 vdd c4 r24 r15 c5 d1 c1 c2 gnd gnd gnd gnd lp package typical pcb layout lp package schematic corresponding to typical pcb layout pcb thermal vias trace (2 oz.) signal (1 oz.) ground (1 oz.) thermal (2 oz.) solder a4915 c4 c5 r24 r15 a4915 vreg lss hc braken dir enable fault vdd vdd tdead speed vbb gnd cp1 cp2 hb ha pad q5 r5 r11 outb c9 q2 r2 r8 glb ghb sb cb q6 r6 r12 outc c10 q3 r3 r9 glc ghc sc cc q4 r4 r10 outa c8 q1 r1 r7 gla gha sa ca vbb c1 c2 figure 4. typical application information for lp package
3-phase mosfet driver a4915 14 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com cx 18v ghx sx glx lss 18v 18v vreg 18v 18v 14v vbb 18v 18v 14v vdd 6v vreg 18v 6v 6v 5 k vdd speed brake dir enable 2 k 6v 6v 50 k vdd ha hb hc 6v 6v vdd vdd 2 k 50 k cp1 18v cp2 fault 6v figure 5. supplies figure 6. fault output figure 7. charge pump figure 8. logic inputs with pull-down: braken, dir, enable figure 9. hall inputs with pull-up: ha, hb, hc figure 11. speed input figure 10. gate drive outputs input / output structures
3-phase mosfet driver a4915 15 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com package et, 28-pin qfn with exposed thermal pad 0.25 +0.05 ?0.07 0.50 0.90 0.10 c 0.08 29x seating plane c a terminal #1 mark area b exposed thermal pad (reference only, terminal #1 identifier appearance at supplier discretion) for reference only; not for tooling use (reference jedec mo-220vhhd-1) dimensions in millimeters exact case and lead configuration at supplier discretion within limits shown c reference land pattern layout (reference ipc7351 qfn50p500x500x100-29v1m); all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and pcb layout tolerances; when mounting on a multilayer pcb, thermal vias at the exposed thermal pad land can improve thermal dissipation (reference eia/jedec standard jesd51-5) 28 2 1 a 28 1 2 pcb layout reference view b 3.15 0.73 max 3.15 3.15 3.15 0.30 1 28 0.50 1.15 4.80 4.80 c 5.00 0.15 5.00 0.15 d d coplanarity includes exposed thermal pad and terminals
3-phase mosfet driver a4915 16 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com package lp, 28-pin tssop with exposed thermal pad a 1.20 max 0.15 0.00 0.30 0.19 0.20 0.09 8o 0o 0.60 0.15 1.00 ref c seating plane c 0.10 28x 0.65 bsc 0.25 bsc 2 1 28 9.700.10 4.400.10 6.400.20 gauge plane seating plane a terminal #1 mark area b for reference only; not for tooling use (reference mo-153 aet) dimensions in millimeters dimensions exclusive of mold flash, gate burrs, and dambar protrusions exact case and lead configuration at supplier discretion within limits shown b exposed thermal pad (bottom surface) branded face 5.08 nom 3 nom c reference land pattern layout (reference ipc7351 sop65p640x120-29cm); all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and pcb layout tolerances; when mounting on a multilayer pcb, thermal vias at the exposed thermal pad land can improve thermal dissipation (reference eia/jedec standard jesd51-5) 6.10 0.65 0.45 1.65 3.00 5.00 28 2 1 pcb layout reference view c
3-phase mosfet driver a4915 17 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com revision history revision current revision date description of revision rev. 1 april 1, 2013 update ec table parameters copyright ?2012-2013, allegro microsystems, llc allegro microsystems, llc reserves the right to make, from time to time, such de par tures from the detail spec i fi ca tions a s may be required to permit improvements in the per for mance, reliability, or manufacturability of its products. before placing an order, the user is cautioned to verify that the information being relied upon is current. allegro?s products are not to be used in life support devices or systems, if a failure of an allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system. the in for ma tion in clud ed herein is believed to be ac cu rate and reliable. how ev er, allegro microsystems, llc assumes n o re spon si bil i ty for its use; nor for any in fringe ment of patents or other rights of third parties which may result from its use. for the latest version of this document, visit our website: www.allegromicro.com

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