page 1 of 6 3976 the a3976 is designed to drive both windings of a bipolar stepper motor or bidirectionally control two dc motors. both h-bridges are capable of continuous output currents of up to +/- 500 ma and operating voltages to 27v. free wheeling, substrate isolated diodes are included for output transient suppression when switching motors or other inductive loads. for each bridge the phase input controls load current polarity by selecting the appropriate source and sink driver pair. the enable input, when held high, enables the respective output h-bridge. when both enable pins are held low the device will enter sleep mode and consume less than 100 m a. the a3976 is protected to ensure safe operation in harsh operating environments and was designed specifically for automotive applications. protection circuitry will check for open or shorted load, motor lead short to ground or supply, vbb overvoltage, vcc undervoltage, and thermal shutdown. if any of these conditions are detected the outputs will be disabled and fault information will be output to diagnostic pins fault1 and fault2. the a3976 is supplied in a 24-lead plastic soic with a copper batwing tab (suffix lb). features ? 500 ma continuous output rating ? 35v load dump survival ? output short circuit protection ? coded fault diagnostic outputs ? low current standby mode ? open load monitor ? low current standby mode ? vbb over voltage shutdown ? internal thermal shutdown circuitry ? internal low parasitic free wheeling diodes ? crossover current protection 4 3 2 1 8 6 7 5 12 11 10 9 21 22 23 24 17 19 18 20 13 14 15 16 enable1 v bb phase1 nc nc ground ground n/c out1a n/c fault1 out1b phase2 nc v cc enable2 fault2 out2b out2a n/c n/c ground nc ground A3976KLB absolute maximum ratings at t a = +25 c operating supply voltage, v bb .................... 27 v non-operating supply voltage .................... 35 v output current, i out ............................ 500 ma* logic supply voltage, v cc .......................... 7.0 v fault output voltage ................................... 7.0 v logic input voltage range, v in ......................... -0.3 v to v cc + 0.3 v package power dissipation (t a = +25 c), p d A3976KLB.................................. 2.2 w operating temperature range, t a .............................. -40 c to +125 c junction temperature, t j ......................... +150 c storage temperature range, t s .............................. -55 c to +150 c * output current rating may be limited by duty cycle, ambient temperature, and heat sinking. under any set of conditions, do not exceed the specified current rating or a junction temperature of 150 c. preliminary datasheet - 12/20/01 (subject to change without notice) d ual full bridge p rotected motor driver
page 2 of 6 3976 C dual full bridge protected motor driver functional block diagram (one of two bridges shown) control logic diagnostic logic out1a v bb out1b v cc ground phase1 enable1 to bridge 2 to bridge 2 out2a out2b phase2 enable2 fault1 fault2 thermal shutdown short to supply monitor short to ground monitor over/under voltage monitor input pull down input logic phase enable outa outb x 0 off off 0 1 low high 1 1 high low fault logic fault condition fault1 fault2 thermal shutdown low low short to battery or open load low high short to ground high low normal operation high high
page 3 of 6 3976 C dual full bridge protected motor driver electrical characteristics at t a = -40c to +125c, v bb = 16v, v cc = 4.5 to 5.5 v (unless noted otherwise) limits characteristics symbol test conditions min. typ. max. units output drivers load supply voltage range v bb operating 6 C 27 v logic supply range v cc operating 4.5 5.5 v output current limit i cl outputs a or b = ground 0.7 1.1 C a outputs a or b = v bb 0.7 1.1 C a output leakage current i cex v out = v bb C <1.0 50 a v out = 0 v C <1.0 -50 m a output saturation voltage v ce(sat) source driver, i out = -350 ma C 1.0 1.2 v source driver, i out = -500 ma C 1.2 1.3 sink driver, i out = +350 ma C 0.2 0.4 v sink driver, i out = +500 ma C 0.4 0.6 v clamp diode forward voltage v f i f = 500 ma (sink / ground clamp) C 1.2 1.5 v (flyback or ground clamp) i f = 500 ma (source / flyback) C 1.55 2.0 v control logic motor supply current i bb enable1 = enable2 = high C 7 10 ma (no load) sleep mode enable1 = enable2 = low C C 25 a logic supply current i cc enable1 = enable2 = high C 45 50 ma sleep mode, enable1 = enable2 = low C C 75 a logic input voltage v in(1) 0.7v cc C - v v in(0) C C .3v cc v logic input current i in(1) v in = 5 v C 50 100 a i in(0) v in = 0 v C -1.0 -2.0 a
page 4 of 6 3976 C dual full bridge protected motor driver electrical characteristics at t a = -40c to +125c, v bb = 16 v, v cc = 4.5 to 5.5 v (unless noted otherwise) limits characteristics symbol test conditions min. typ. max. units fault circuitry fault output leakage current i f-leak v f = 5 v, no faults - - 10 m a fault output voltage v fl fault condition asserted, i f = 25 m a C 0.8 v fault output current i f v f = 5 v, enable = high 25 50 75 m a output open load current i out-o.l. v bb = 12 v C 2 C ma thermal fault temp. t f C 170 C c thermal fault hysteresis t fhys C 10 C c ovlo enable threshold v bb rising 27 30 33 v ovlo hysteresis 1.5 v uvlo enable threshold v cc rising 3.5 4 4.49 v uvlo hysteresis C 400 C mv timing open fault to reset delay t rs v bb = 12 v C C 25 m s phase_x delay to open fault t of v bb = 12 v C 8 C m s phase_x delay to s.c. fault t sc v bb = 12 v C 5 C m s enable_x delay to fault t of v bb = 12 v C 5 C m s propagation delay times t pd i out = 0.35a, 50%to 90% enable on to source on C 0.3 s enable off to source off C 0.4 s enable on to sink on C 0.3 s enable off to sink off C 0.2 s phase change to sink on C 4.0 s phase change to sink off C 0.3 s phase change to so urce on C 4.0 s phase change to so urce off C 0.4 s cross over dead time t codt 1k w (1k+1k) load (v bb to out to gnd) 0.5 3.0 6.0 s
page 5 of 6 3976 C dual full bridge protected motor driver application notes open load protection. during normal pwm operation, diagnostic circuitry will look for a minimum source current level after a bridge is signalled on. additionally, the diode flyback is monitored on the proper output. the logic will signal a fault and disable the outputs if it determines that the current is below the minimum level and no flyback is occurring. if the inductive load is too large, the current would take too long to reach the minimal level and a false open load would be reported. it is recommended that the inductive load be less than 38 mh. short circuit protection. internal sense resistors in series with v bb and ground will trip the fault circuitry if greater than 1.1 a is detected. to prevent false overcurrent events due to reverse recovery spikes of the clamp diodes, the current monitor is blanked for 5 m s after a high side is signalled to turn on. if an additional input command follows after the initial fault, the selected pair of drivers will pulse on for the 5 m s blanking duration. the short circuit fault will remember the input state where the fault occurred and will wait for that particular logic state after the short has been removed before normal operation is allowed to resume. thermal protection . circuitry turns off all drivers when the junction temperature reaches 170c typically. it is intended only to protect the device from failures due to excessive junction temperatures and has a hysteresis of approximately 15c. layout. the printed wiring board should use a heavy ground plane. for optimum electrical and thermal performance, the driver should be soldered directly onto the board. the load supply terminal, v bb , should be decoupled with an electrolytic capacitor (> 47 f is recommended) placed as close to the device as possible.
page 6 of 6 3976 - dual full bridge protcted motor driver terminal list name description soic - 24 v bb motor supply voltage 1 enable1 control logic C bridge 1 2 phase1 control logic C bridge 1 3 ground power ground return 18,19,6,7 out1a bridge 1 output a 9 fault1 diagnostic output 11 out1b bridge 1 output b 12 out2b bridge 2 output b 13 fault2 diagnostic output 14 out2a bridge 2 output a 16 phase2 control logic C bridge 2 22 enable2 control logic C bridge 2 23 v cc logic supply 24 nc no connect 4,5,8,15,17,20,21
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