A3932 Three-Phase Power MOSFET Controller Last Time Buy This part is in production but has been determined to be LAST TIME BUY. This classification indicates that the product is obsolete and notice has been given. Sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because of obsolescence in the near future. Samples are no longer available. Date of status change: December 1, 2015 Deadline for receipt of LAST TIME BUY orders: May 31, 2016 Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to A3938SLDTR-T. NOTE: For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative. Allegro MicroSystems, LLC reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. A3932 Three-Phase Power MOSFET Controller Features and Benefits ▪Drives wide range of N-channel MOSFETs ▪Synchronous rectification ▪Power MOSFET protection ▪Adjustable dead time for cross-conduction protection ▪100% duty cycle operation ▪Selectable fast or slow current-decay modes ▪Internal PWM peak current control ▪High-current gate drive ▪Motor lead short-to-ground protection ▪Internal 5 V regulator ▪Brake input ▪PWM torque-control input ▪Fault-diagnostic output ▪Tachometer output ▪Thermal shutdown ▪Undervoltage protection Description The A3932 is a three-phase MOSFET controller for use with bipolar brushless DC motors. Its high gate-current drive capability allows driving a wide range of N-channel power MOSFETs and can support motor supply voltages to 50 V. Bootstrapped high-side drive blocks provide the floating positive supplies for the gate drive and minimize the component count normally required. The high-side circuitry also employs a unique FET monitoring circuit that ensures the gate voltages are at the proper levels before turn-on and during the ON cycle. Internal fixed off-time PWM current-control circuitry can be used to regulate the maximum load current to a desired value. The peak load-current limit is set by the user’s selection of an input reference voltage and external sensing resistor. The fixed off-time pulse duration is set by a user-selected external RC timing network. For added flexibility, the PWM input can be used to provide speed/torque control, allowing the internal current control circuit to set the maximum current limit. Optional synchronous rectification is included. This feature will short out the current path through the power MOSFET reverse body diodes during the PWM off-cycle current decay. This can minimize power dissipation in the power MOSFET, eliminate the need for external power clamp diodes, and potentially allow more economical choices for the MOSFET application. Packages 38-pin TSSOP (suffix LD) The A3932 includes the commutation logic for Hall sensors configured for 120 degree spacing. Power MOSFET protection features include bootstrap capacitor charging current monitor, undervoltage monitor, motor-lead short-to-ground, and thermal shutdown. The ‘–S–’ part-number suffix indicates an operating temperature range of -20°C to +85°C. The ‘–LD–’ suffix indicates a 38‑lead TSSOP package. The initial ‘–TR–’ variant suffix indicates tape and reel packing. The ‘–T’ final variant suffix indicates lead (Pb) free composition, with 100% matte tin leadframe plating. Not to scale 26301.101I A3932 Three-Phase Power MOSFET Controller Selection Guide Part Number A3932SLDTR-T Packing 4000 pieces per reel Absolute Maximum Ratings Characteristic Symbol Notes Rating Units 50 V Supply Voltage VBB Peak Regulator Voltage VREG 15 V VIN –0.3 to VLCAP + 0.3 V VSENSE –5 to 1.5 V Logic Input Voltage Range Sense Voltage Range Output Voltage Range SA, SB, SC Pins GHA, GHB, GHC Pins CA, CB, CC Pins Operating Ambient Temperature V TA Range S –5 to 50 V –5 to VBB + 17 V VSx + 17 V –20 to 85 ºC Junction Temperature TJ 150 ºC Storage Temperature Tstg –55 to 150 ºC Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 2 A3932 Three-Phase Power MOSFET Controller Pin-Out Diagram 38-pin TSSOP (suffix LD) RESET 1 38 NC GLC 2 37 NC SC 3 36 PGND NC 4 35 AGND NC 5 34 DEAD GHC 6 33 REF CC 7 32 SENSE GLB 8 31 RC SB 9 30 PWM GHB 10 29 TACH CB 11 28 SR GLA 12 27 BRAKE SA 13 26 DIR GHA 14 25 H2 CA 15 24 H3 VREG 16 23 NC LCAP 17 22 H1 NC 18 21 VBB FAULT 19 20 MODE CONTROL LOGIC FAULT Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 3 A3932 Three-Phase Power MOSFET Controller Functional Block Diagram NOTE — For 12 V applications, VBB is shorted to VREG. The VREG absolute maximum rating (15 V) must not be exceeded. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 A3932 Three-Phase Power MOSFET Controller ELECTRICAL CHARACTERISTICS: unless otherwise noted at TA = 25°C; VBB = 18 V to 50 V; CLCAP, Cboot = 0.1 µF; CREG = 10 µF; Cload = 3300 pF; fPWM = 22.5 kHz Square Wave; Two Phases Active. Limits Parameter Symbol Conditions Min Typ Max Units – – 8.0 mA Supply Current Quiescent Current IBB Reference Voltage VLCAP ILCAP = -3 mA 4.75 5.0 5.25 V Output Voltage VREG VBB = VREG ≤15 V, IREG = -10 mA 10.8 – 13.2 V 18 V ≤ VBB ≤ 50 V, IREG = -10 mA 12.4 13 13.6 V – VBB - 2.5 – V – 25 – mV RESET high, coast mode, stopped VBB = 13.2 V to 18 V, IREG = -10 mA Output Voltage Regulation ΔVREG(ΔIREG) IREG = -1 to -30 mA, coast ΔVREG(ΔVBB) IREG = -10 mA, coast – 40 – mV VIH All inputs except SR 2.0 – – V SR input only 3.0 – – V All inputs except SR – – 0.8 V SR input only – – 1.8 V Digital Logic Levels Logic Input Voltage VIL Logic Input Current IIH VIH = 2 V -30 – -90 µA IIL VIL = 0.8 V -50 – -130 µA – V Gate Drive Low-Side Output Voltage VGLxH IGLx = 0 High-Side Output Voltage VGHxH IGHx = 0 Pulldown Switch Resistance rDS(on) Pullup Switch Resistance rDS(on) VREG - 0.8 VREG - 0.5 10.4 11.6 12.8 V IGLx = 50 mA – 4.0 – Ω IGHx = -50 mA – 14 – Ω Low-Side Output Switching Time trGLx 10% to 90%, with Cload – 120 – ns tfGLx 90% to 10%, with Cload – 60 – ns High-Side Output Switching Time trGHx 10% to 90%, with Cload – 120 – ns tfGHx 90% to 10%, with Cload – 60 – ns tpr GHx, GLx rising, Cload = 0 – 220 – ns tpf GHx, GLx falling, Cload = 0 – 110 – ns Propagation Delay Time (PWM to gate output) Maximum Dead Time tdead GHx to GLx, VDEAD = 0 V, Cload = 0 3.5 5.6 7.6 µs Minimum Dead Time tdead GLx to GHx, IDEAD = 780 µA, Cload = 0 50 100 150 ns NOTES: 1. Typical Data is for design information only. 2. Negative current is defined as coming out of (sourcing) the specified device terminal. Continued — Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 5 A3932 Three-Phase Power MOSFET Controller ELECTRICAL CHARACTERISTICS: unless otherwise noted at TA = 25°C; VBB = 18 V to 50 V; CLCAP, Cboot = 0.1 µF; CREG = 10 µF; Cload = 3300 pF; fPWM = 22.5 kHz Square Wave; Two Phases Active. Parameter Symbol Conditions Limits Min Typ Max Units 100 – – mA 10.4 11.6 12.8 V Bootstrap Capacitor Bootstrap Charge Current ICx Bootstrap Output Voltage VCx VSx = 0, ICx = 0, VREG = 13 V Bootstrap Resistance rCx ICx = -50 mA – 9.0 12 Ω Vio 0 V ≤ VIC ≤ 1.5 V – – ±5.0 mV ISENSE VIC ≥ 0 V, VID ≤ 1.5 V – -25 – µA REFERENCE Input Current IREF VIC ≥ 0 V, VID ≤ 1.5 V – 0 – µA Blank Time tblank RT = 56 kΩ, CT = 470 pF – 0.91 – µs IRC -0.9 -1.0 -1.1 mA VRCL 1.0 1.1 1.2 V VRCH 2.7 3.0 3.3 V Bootstrap Charge Threshold ICx – -9.0 – mA Motor Short-to-Ground Monitor VDSH VBB - VSX, high side on 1.3 2.0 2.7 V Undervoltage Threshold UVLO Increasing VREG 9.2 9.7 10.2 V Decreasing VREG 8.6 9.1 9.6 V Current Limit Circuitry Input Offset Voltage SENSE Input Current RC Charge Current RC Voltage Threshold Protection Circuitry FAULT Output Voltage VFAULT IO = 1 mA – – 0.5 V TACH Output Voltage VTACH IO = 1 mA – – 0.5 V TACH Output Pulse Width tTACH IO = 1 mA, CTACH = 50 pF – 0.75 – µs Thermal Shutdown Temp. TJ – 165 – °C Thermal Shutdown Hysteresis ∆TJ – 10 – °C Thermal Resistance RθJA Package EQ Four-layer PCB – 37 – °C/W Package LD Four-layer PCB – 51 – °C/W NOTES: 1. Typical Data is for design information only. 2. Negative current is defined as coming out of (sourcing) the specified device terminal. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 6 A3932 Three-Phase Power MOSFET Controller Terminal Descriptions LD Name 1 RESET 2 GLC 3 SC 4,5,18, NC 23,37,38 6 GHC 7 CC 8 GLB 9 SB 10 GHB 11 CB 12 GLA 13 SA 14 GHA 15 CA 16 VREG 17 LCAP 19 FAULT 20 MODE 21 VBB 22 H1 24 H3 25 H2 26 DIR 27 BRAKE 28 SR 29 TACH 30 PWM 31 RC 32 SENSE 33 REF 34 DEAD 35 AGND 36 PGND RESET — A logic input used to enable the device, internally pulled up to VLCAP (+5 V). A RESET = 1 will disable the device and force all gate drivers to 0 V, coasting the motor. A RESET = 0 allows the gate drive to follow the commutation logic. The RESET = 1 overrides BRAKE. GLA/GLB/GLC — Low-side, gate-drive outputs for external NMOS drivers. External series-gate resistors (as close as possible to the NMOS gate) can be used to control the slew rate seen at the power-driver gate, thereby controlling the di/dt and dv/dt of the SA/SB/SC outputs. GLx = 1 (or “high”) means that the upper half (PMOS) of the driver is turned on and its drain will source current to the gate of the low-side FET in the external motor-driving bridge. GLx = 0 (or “low”) means that the lower half (NMOS) of the driver is turned on and its drain will sink current from the external FET’s gate circuit. SA/SB/SC — Directly connected to the motor, these terminals sense the voltages switched across the load. These terminals are also connected to the negative side of the bootstrap capacitors and are the negative supply connections for the floating highside drivers. GHA/GHB/GHC — High-side, gate-drive outputs for external NMOS drivers. External series-gate resistors can be used to control the slew rate seen at the power-driver gate, thereby controlling the di/dt and dv/dt of the SA/SB/SC outputs. GHx = 1 (or “high”) means that the upper half (PMOS) of the driver is turned on and its drain will source current to the gate of the high-side FET in the external motor-driving bridge. GHx = 0 (or “low”) means that the lower half (NMOS) of the driver is turned on and its drain will sink current from the external FET’s gate circuit. CA/CB/CC — High-side connections for the bootstrap capacitors, positive supply for high-side gate drivers. The bootstrap capacitors are charged to approximately VREG when the associated output Sx terminal is low. When the output swings high, the voltage on this terminal rises with the output to provide the boosted gate voltage needed for N-channel power MOSFETs. continued next page Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 A3932 Three-Phase Power MOSFET Controller Terminal Descriptions (cont’d) FAULT — Open-drain output to indicate fault condition; FAULT = 1 (external pull-up) for any of the following: 1 – invalid HALL input code, 2 – undervoltage condition detected at VREG. 3 – thermal shutdown, or 4 – motor lead (SA/SB/SC) shorted to ground. Except for a short-to-ground fault that only turns off the high-side drivers, faults will force a coast condition that turns off all power MOSFETs. Only the short-to-ground fault is latched but is cleared at each commutation. If the motor has stalled due to a short-to-ground being detected, toggling the RESET terminal or repeating a power-up sequence will clear the fault. Typically pulled up to VLCAP (+5 V) with an external 5.1 kΩ resistor. MODE — A logic input to set current-decay method, internally pulled up to VLCAP (+5 V). When in slow-decay mode (MODE = 1), only the high-side MOSFET is switched off during a PWM-off cycle. The fast-decay mode (MODE = 0) switches both the high-side and low-side MOSFETs. H1/H2/H3 — Hall-sensor inputs; internally pulled up to VLCAP (+5 V). Configured for 120° electrical spacing. DIR — A logic input to reverse rotation, see Commutation Truth Table. Internally pulled up to VLCAP (+5 V). BRAKE — An active-low logic input for a braking function. A BRAKE = 0 will turn on the low-side FETs and turn off the high-side FETs. This will effectively short-circuit the BEMF in the windings and brake the motor. The braking torque applied will depend on the speed. Internally pulled up to VLCAP (+5 V). RESET = 1 overrides BRAKE and will coast the motor. SR — Synchronous rectification input. An SR = 0 disables this feature, forcing current decay through the body diodes of the power MOSFETs. An SR = 1 will result in appropriate highand low-side gate outputs to switch in response to a PWM-off command. Internally pulled up to VLCAP (+5 V). See also the Input Logic table. TACH — An open-drain digital output whose frequency is proportional to speed of rotation. A pulse appears at every HALL transition. Typically pulled up to VLCAP (+5 V) with an external 5.1 kΩ resistor. PWM — Speed control input, internally pulled up to VLCAP (+5 V). A PWM = 0 turns off selected drivers. A PWM = 1 will turn on selected drivers as determined by H1/H2/H3 input logic. Holding PWM = 1 allows speed/torque control solely by the internal current-limit circuit with the REF analog voltage. See also the Input Logic table . RC — An analog input used to set the fixed off time with an external resistor (RT) and capacitor (CT). The tblank time is controlled by the value of the external capacitor (see Applications Information). See Application Information. SENSE — An analog input to the current-limit comparator. A voltage representing load current appears on this terminal during on time, when it reaches REF voltage, the comparator trips and load current decays for the fixed off-time interval. Voltage transients seen at this terminal when the drivers turn on are ignored for time tblank. REF — An analog input to the current-limit comparator. Voltage applied here with respect to AGND sets the peak load current. Ipeak = VREF/RS. VREG — A regulated 13 V output; supply for low-side gate drive and bootstrap capacitor charge circuits. It is good practice to connect a decoupling capacitor from this terminal to AGND, as close to the device terminals as possible. This terminal should be shorted to VBB for 12 V applications. VBB — The A3932 supply voltage. It is good practice to connect a decoupling capacitor from this terminal to AGND, as close to the device terminals as possible. LCAP — Connection for 0.1 µF decoupling capacitor for the internal 5 V reference. This terminal can source no more than 3 mA for the DEAD input, TACH and FAULT outputs. DEAD — An analog input. A resistor between DEAD and LCAP is selected to adjust the turn-off to turn-on time. This delay is needed to prevent shoot-through in the external power MOSFETs. See Applications Information for details on setting dead time. AGND — The low-level (analog) reference point. PGND — The return for all low-side gate drivers. This should be connected to the system power ground. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 8 A3932 Three-Phase Power MOSFET Controller Commutation Truth Table Logic Inputs H2 H3 H1 1 1 1 0 0 0 1 1 1 0 0 0 0 0 1 1 1 0 0 0 1 1 1 0 DIR GLA GLB 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 1 1 0 0 0 1 0 0 0 1 1 1 0 0 0 1 1 Driver Outputs GLC GHA 1 1 0 0 0 0 0 0 0 1 1 0 1 0 0 0 0 1 0 0 1 1 0 0 GHB GHC 0 1 1 0 0 0 0 0 0 0 1 1 0 0 0 1 1 0 1 1 0 0 0 0 Motor Terminals SA SB SC H Z L L Z H L Z H H Z L Z H H Z L L Z L L Z H H L L Z H H Z H H Z L L Z Input Logic MODE PWM SR RESET 0 0 1 1 0 0 1 1 X 0 1 0 1 0 1 0 1 X 0 0 0 0 1 1 1 1 X 0 0 0 0 0 0 0 0 1 Operation PWM chop mode, fast decay, all drivers off Peak current limit, selected drivers on PWM chop mode. slow decay, selected low side drivers on Peak current limit, selected drivers on PWM chop mode, fast decay with opposite of selected drivers on Peak current limit, selected drivers on PWM chop, slow decay with both low-side drivers on Peak current limit, selected drivers on All gate drive outputs off, clear fault logic, coast L = Low (less positive) level H = High (more positive) level X = Don’t care Z = High impedance 1 = Active or true logic condition 0 = Inactive or false logic condition Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9 A3932 Three-Phase Power MOSFET Controller Applications Information Synchronous Rectification. To reduce power dissipation in the external MOSFETs, the A3932 control logic turns on the appropriate low-side and high-side driver during the load-current recirculation, PWM-off cycle. Synchronous rectification allows current to flow through the MODE-selected MOSFET, rather than the body diode, during the decay time. The body diodes of the SR power MOSFETs will conduct only during the dead time required at each PWM transition. Dead Time. It is required to have a dead-time delay between a high- or low-side turn off and the next turn-on event to prevent cross conduction. The potential for cross conduction occurs with synchronous rectification, direction changes, PWM, or after a bootstrap capacitor charging cycle. The dead time is set by a resistor (Rdead) between the DEAD terminal and LCAP (+5 V) and can be set between 100 ns and 5.5 µs. The following equations are valid for Rdead between 5.6 kΩ and 470 kΩ. At 25°C, tdead (nom, ns) = 37 + (11.9 x 10-3 x (Rdead + 500)) For predicting worst case, over voltage and temperature extremes, tdead (min, ns) = 10 + (6.55 x 10-3 x (Rdead + 350)) tdead (max, ns) = 63 + (17.2 x 10-3 x (Rdead + 650)) For comparison with IDEAD test currents, IDEAD = (VLCAP – Vbe)/(Rdead + Rint) where (nominal values) VLCAP = 5 V, Vbe = 0.7 V at 25°C, and Rint = 500 Ω. Rather than use Rdead values near 470 kΩ, set DEAD = ground (VDEAD = 0 V), which activates an internal (IDEAD = 10 µA) current source. The choice of power MOSFET and external series gate resistance determines the selection of the dead-time resistor. The dead time should be made long enough to cover the variation of the MOSFET gate capacitance and series gate resistance (both external and internal to the A3932) tolerances. Decoupling. The internal reference, VREG, supplies current for the gate-drive circuit. As the gates are driven high they will require current from an external capacitor to support the transients. This capacitor should be placed as close as possible to the VREG terminal. Its value should be at least 20 times larger than the bootstrap capacitor. Additionally, a 0.1 µF (or larger) decoupling capacitor should be connected between LCAP and AGND as close to the device terminals as possible. Protection Circuitry. The A3932 has several protection features: 1) Bootstrap Circuit. The bootstrap capacitor is charged whenever a low-side MOSFET is on, Sx output goes low, and the load current recirculates. This happens constantly during normal operation. The high-side MOSFET will not be allowed to turn on before the charging has decayed to less than approximately 9 mA. No fault will be registered. When a phase’s high-side driver is on for a long time (100% duty cycle operation) its charge pump is designed to maintain VGS > 9 V on the bridge FET if IGHx (the load on the gate driver) < 10 µA. 2) Hall Invalid. Illegal codes for the HALL inputs (000 or 111) will force a fault and coast the motor. Noisy Hall lines may cause double TACH pulses and, therefore, code errors that produce faults. Additional external pullup loading and filtering may be required depending on the system. 3) VREG Undervoltage. An internal regulator supplies the low-side gate driver and the bootstrap charge current. It is critical to ensure that VREG is at the proper level before enabling any of the outputs. The undervoltage circuit is active during power-up and will force a motor coast condition (all gate drives, GHx and GLx = 0) until VREG is greater than approximately 9.7 V. 4) Thermal Shutdown. A junction temperature greater than 165°C will signal a fault and coast the motor (all gate drives LOW). If the junction temperature then falls to less than 155°C (hysteresis), the fault will be cleared. 5) Motor Lead Shorted to Ground. The A3932 will signal a fault if a motor lead is shorted to ground. A short to ground is assumed after a high side is turned on and greater than 2 V is measured between the drain (VBB) and source (SA/SB/SC) of the high-side power MOSFET. This fault is cleared at the beginning of each commutation. If a stalled motor results from a fault, the fault can only be cleared by toggling the RESET terminal or by a power-up sequence. continued next page Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 10 A3932 Three-Phase Power MOSFET Controller Applications Information (cont’d) Current Control. Internal fixed off-time PWM circuitry is implemented to limit load current to a desired value. When a high-side and low-side MOSFET are turned on, current will increase in the motor winding until it reaches a value given by ITRIP ≈ VREF/RS. Because the load current does not flow through the sense resistor during a dynamic brake, care must be taken to ensure that the power MOSFET’s maximum ratings are not exceeded. At the trip point, the sense comparator resets the sourceenable latch, turning off the high-side driver. Load inductance causes the current to recirculate (decay) for the fixed off time. The current path during recirculation is determined by the configuration of the MODE and SR inputs. Low-Voltage Operation. Although VREG can be connected to VBB for 12 V systems, the VREG maximum rating of 15 V must be observed including transients. If transients cannot be adequately controlled, use VREG in the regulator mode (not connected to VBB). With VBB less than 18 V, the VREG output voltage level specification may not be met. Note that in this mode the VREG undervoltage threshold may leave the system with little headroom if VBB is less than 12 V. An external resistor (RT) and capacitor (CT), connected in parallel from the RC terminal to AGND, are used to set the fixed off-time period (toff = RT x CT). RT should be in the range of 10 kΩ to 500 kΩ. The toff should be in the range of 10 µs to 50 µs. Larger values for toff can result in audible noise problems. Torque control can be implemented by varying the REF input voltage as long as the PWM input stays high. If direct control of the torque/current is desired by PWM input, a voltage can be applied to the REF input to set an absolute maximum current limit. PWM Blank. The capacitor (CT) also serves as the means to set the blank time duration. At the end of the PWM off cycle, a high-side gate selected by the commutation logic will turn on. At this time, large current transients can occur during the reverse recovery time (trr) of the intrinsic body diodes of the external power MOSFETs. To prevent false tripping of the current-sense comparator, the blank function disables the comparator for a time tblank = 1.9 x CT/(0.001 - [2/RT]) The user must ensure that CT is large enough to cover the current-spike duration. Braking. The A3932 will dynamically brake by forcing all low-side MOSFETs on and all high-side MOSFETs off. This will effectively short-circuit the BEMF and brake the motor. During braking, the load current can be approximated by: IBRAKE = VBEMF/RL RESET = 1 overrides BRAKE and turns all motor bridge FETs off, coasting the motor. Driving an H Bridge. The A3932 may be used to drive an H bridge (e.g., a brush dc motor load) by hard wiring one state for the Hall inputs (e.g., H1 = H2 = 1 (HIGH), H3 = 0 (LOW)). Leave the appropriate phase driver outputs floating (in this case CC, GHC, SC, and GLC because, from the Commutation Truth Table, SC = Z). The DIR input controls the motor rotation while the PWM, MODE, and SR inputs control the motor current behavior as described in the Input Logic table. Layout. Careful consideration must be given to PCB layout when designing high-frequency, fast-switching, high-current circuits. 1) The analog ground (AGND), the power ground (PGND), and the high-current return of the external MOSFETs (the negative side of the sense resistor) should return separately to the negative side of the motor supply filtering capacitor. This will minimize the effect of switching noise on the device logic and analog reference. 2) Minimize stray inductances by using short, wide copper runs at the drain and source terminals of all power MOSFETs. This includes motor lead connections, the input power buss, and the common source of the low-side power MOSFETs. This will minimize voltages induced by fast switching of large load currents. 3) Kelvin connect the SENSE terminal PC trace to the positive side of the sense resistor. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 11 A3932 Three-Phase Power MOSFET Controller Package LD, 38-Pin TSSOP 1.60 9.70 4º 0.50 38 0.30 38 0.15 4.40 6.40 6.00 A 1 2 0.25 38X SEATING PLANE 0.10 C 0.22 0.50 B PCB Layout Reference View SEATING PLANE GAUGE PLANE C All dimensions nominal, not for tooling use (reference JEDEC MO-153 BD-1) Dimensions in millimeters 1.20 MAX 0.10 1 2 A Terminal #1 mark area B Reference pad layout (reference IPC SOP50P640X110-38M) All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances Copyright ©2002-2015, Allegro MicroSystems, LLC Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, 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 information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its use; nor for any infringement 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 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 12