8925 41 NC 40 FAULT 43 TACH 42 OUT A 1 OUTB 44 POLE LOGIC GROUND LOGIC SUPPLY 2 V CC 3 NC 4 OUT C 6 5 ENABLE 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS POWER GROUND 39 7 POWER GROUND The A8925CEB is a DMOS three-phase brushless dc motor controller/driver designed for use in Winchester disk drives and other data storage applications. The power output stages are capable of ±4 A output currents and have DMOS power outputs with less than 0.25 Ω rDS(on) for low power dissipation. Intrinsic ground clamp and flyback diodes protect the output drivers when switching inductive loads. Thermal shutdown circuitry is provided to protect the device from excessive junction temperature. T C U Y D L O N R P EO D C E N U E N R I T E F N E O R C S R I D FO — 38 9 37 10 36 CHARGE PUMPS 8 13 CIRCUITRY 35 SEQUENCING 12 AND CONTROL 11 34 33 14 15 31 16 30 + 29 POWER GROUND 3 27 28 H NC 26 2 H 25 NC 24 1 H 23 SUB BRAKE 21 ERROR AMP LOAD SUPPLY 19 20 REFERENCE VSENSE 18 SUB 22 V BB 17 COMP. POWER GROUND 32 Dwg. PP-034 ABSOLUTE MAXIMUM RATINGS AT TA = +25°C Load Supply Voltage, VBB ..................... 14 V Output Current, IOUT .......................... ±4.0 A Logic Supply Voltage, VCC ..................... 14 V Logic Input Voltage Range, VIN ................................ -0.3 V to +6.0 V Package Power Dissipation, PD ......................................... See Graph Operating Temperature Range, TA ..................................... 0 °C to +70°C Junction Temperature, TJ ............... +150°C† Storage Temperature Range, TS ................................ -55°C to +150°C † Fault conditions that produce excessive junction temperature will activate device thermal shutdown circuitry. These conditions can be tolerated, but should be avoided. A transconductance amplifier is used to linearly regulate the load current and control motor speed. Internal current-sensing circuitry eliminates the need for external sense resistors. Analog and digital control circuitry provide complete sequencing of the output drivers as well as providing brake, disable, and tachometer functions. A FAULT output flag indicates the presence of an under-voltage condition on the 12 V supply, excessive junction temperature, or an invalid Hall input combination. The A8925CEB’s commutation logic is compatible with motors that have digital Hall-effect sensors with 120° of electrical separation. Internal charge pump circuitry is provided to drive the Nchannel DMOS source drivers to their required gate voltages. The A8925CEB is provided in a 44-lead PLCC power package for surface-mount applications. The copper batwing provides for maximum allowable package power dissipation in the smallest possible construction. FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ DMOS Outputs Low r DS(on) - 0.25 Ω Maximum Linear Current Control Internal Commutation Circuitry Internal Current Sensing Thermal Shutdown Circuitry Under Voltage Detection Circuitry Fault Output Flag Power Surface-Mount Package Output current rating may be restricted to a value determined by system concerns and factors. These include: system duty cycle and timing, ambient temperature, and use of any heatsinking and/or forced cooling. For reliable operation, the specified maximum junction temperature should not be exceeded. Always order by complete part number: A8925CEB . Data Sheet 26301.30 8925 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS 12.5 T R θJ /W °C =6 ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS 8925 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS 10 7.5 5.0 R 2.5 θJA = 3 0°C /W 0 25 50 75 100 TEMPERATURE IN °C 125 150 Dwg. GP-020B ELECTRICAL CHARACTERISTICS AT TA = +25°C, VCC = VBB = 12 V Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units Logic Supply Voltage VCC Operating 10 12 14 V Load Supply Voltage V BB Operating 10 12 14 V Supply Current ICC Operating — 30 50 mA VENABLE = 0 V Thermal Shutdown TJ — — 2.0 165 4.0 — mA °C IOUT = ±4.0 A, Pulse Test — 0.20 0.25 Ω IOUT = 4.0 A, L = 2 mH 14 — — V VF IF = ±4.0 A — 1.5 2.0 V IDSX VOUT = 14 V — 10 300 µA VOUT = 0 V — -10 -300 µA ENABLE, POLE — — 0.8 V 2.4 — — V — — 0.8 V 3.0 — — V Output Drivers Output ON Resistance Output Sustaining Voltage Clamp Diode Forward Voltage Output Leakage Current rDS(on) VDS(sus) Control Logic Logic Input Voltage VIN(0) VIN(1) Logic Input Voltage VIN(0) BRAKE VIN(1) Logic Input Current IIN(0) VIN = 0.8 V — — -1.0 µA IIN(1) VIN = 2.4 V — — 1.0 µA NOTE: Negative current is defined as coming out of (sourcing) the specified device terminal. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 1990, 1995 Allegro MicroSystems, Inc. Continued next page... 8925 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS ELECTRICAL CHARACTERISTICS CONTINUED Limits Characteristic Symbol Logic Output Voltage (FAULT, TACH) Test Conditions Min. Typ. Max. Units VOUT(0) IOUT = 3 mA — — 0.8 V VOUT(1) IOUT = -50 µA 2.0 — — V IIB VCM = 0.01 V — 5.0 10 µA Input Offset Voltage VOS VCM = 1.0 V — 3.0 5.0 mV Input Common-Mode Voltage Range VIC 0.01 — 6.0 V Error Voltage Gain AVD — 80 — dB Unity Gain Bandwidth BW — 1.0 — MHz Common-Mode Rejection Ratio CMRR — 80 — dB Power Supply Rejection Ratio PSRR — 50 — dB Error Amplifier Input Bias Current VS OUT / V S IN , V CM = 1.0 V Miscellaneous Current Sense Gain AiCS IOUT = -1.0 A 1/1k 1/1.2k 1/1.4k — Current-Sense Matching — IOUT = -1.0 A — ±3.0 ±5.0 % Under-Voltage Trip Point VCC 8.0 — 9.5 V Hall Input Current IIN(0) VIN = 0 V — -500 -1000 µA IIN(1) VIN = 5.0 V — -250 -500 µA Hall Input Threshold VIN — 3.8 — V Hall Input Pull-Up Resistance RPU — 25 — kΩ NOTE: Negative current is defined as coming out of (sourcing) the specified device terminal. COMMUTATION TRUTH TABLE Hall Sensor Inputs Outputs H1 H2 H3 High High High Low Low Low Low Low High High High Low High Low Low Low High High High High High High High High High High High High High High High Low X High Low X High Low X High High Low X X X X X = Irrelevant Z = High Impedance ENABLE BRAKE FAULT OUT A OUT B OUT C High High High High High High High High Z Low Low Z Low Z High High Z Low Z Low Low Z High High High High High Low Low X Z Z Z Z Z Z Z Z Z Low X Low Low Low 8925 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS TERMINAL FUNCTIONS Term. Terminal Name 1 OUTB Function Power DMOS output. 2 LOGIC SUPPLY VCC; low-current 12 V supply for the logic. 3 LOGIC GROUND Low-level logic ground. 4 OUT C 6 ENABLE 7–17 POWER GROUND Power DMOS output. Active high chip enable. Power ground and thermal heat sink. 18 VSENSE External precision resistor for sense-FET current. 19 COMP. Compensation; error amplifier output. 20 REFERENCE VREF ; voltage input that sets the power output current. 21 ERROR AMP. Input that controls the current in the load. 22 LOAD SUPPLY VBB; high-current 12 V supply for the voice-coil motor. 23 BRAKE 24 H1 High-level input from a Hall sensor. 26 H2 High-level input from a Hall sensor. A logic low turns OFF all source drivers and turns ON all sink drivers (shorts the windings to ground). 28 H3 29–39 POWER GROUND High-level input from a Hall sensor. 40 FAULT 42 OUTA 43 TACH Speed reference output; the H1 Hall input divided by the number of motor poles. 44 POLE Designates four- or eight-pole motor; Low = 4 pole, High = 8 pole. Power ground and thermal heat sink. A logic low at this output indicates a thermal shutdown, under -voltage fault, or an invalid Hall input combination. Power DMOS output. FUNCTIONAL DESCRIPTION V BB CHARGE PUMP SENSE AMPLIFIER I OUT . VSENSE 1200 OUT R3 SEQUENTIAL LOGIC R1 C1 RS _VREF ++ ERROR AMPLIFIER OUT C2 V R2 Power Outputs (OUT A, OUTB, and OUTC). The power outputs of the A8925CEB are DMOS transistors with a maximum rDS(on) of 0.25 Ω. Intrinsic ground clamp and flyback diodes clamp transient voltage spikes when switching inductive loads. Internal charge pump circuitry is used to drive the gates of the N-channel source drivers to their required gate voltages. COMP. SUB Dwg. EP-040 Current Control. Current in the load is monitored by an internal sense amplifier that produces an output current that is approximately one twelve hundredth that of the load current (see Figure). This current is output to the VSENSE terminal and develops a voltage Continued next page... 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 8925 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS across RS that equals RS • ILOAD /1200. This sense voltage (VSENSE) is compared to a reference voltage (VREF ) and an error voltage is developed that is gated in by the sequential control logic to drive the gate of the appropriate output sink transistor. A transconductance control function is thus realized where IOUT = V REF • 1200/R S. External components C1, C2, R1, R2, and R3 are compensation components used to obtain optimal response and settling of the current control loop. Information on how to select these components is available. FAULT. The FAULT terminal when low indicates the presence of one of three fault conditions: A) An under-voltage condition on the logic supply. The trip point for this function is between 8 and 9.5 volts. B) An invalid Hall input combination … all inputs High or all inputs Low. C) An excessive device junction temperature. The thermal shutdown circuitry disables the output drivers in addition to forcing the FAULT output signal low. TACH and POLE. In order to develop a low-jitter tachometer signal (TACH) for use in controlling motor speed, the A8925CEB divides the frequency of the H1 input by the number of poles in the motor. This eliminates the jitter caused by variations in Halleffect device placement , sensitivity, and magnet strengths by always changing state when looking at the same magnet/sensor pair. The resulting TACH signal changes state every mechanical revolution of the motor. The POLE input sets the TACH signal for fourpole motors when Low or eight-pole motors when High. HALL INPUTS (H1, H2, H3). The A8925CEB is configured for use with open-collector Hall-effect devices. Internal 25 kΩ pull up resistors to 10 volts are connected to these inputs. ENABLE. The ENABLE terminal when Low puts the device in a low current consumption, power-down mode. When ENABLE is High the device is active. BRAKE. When the BRAKE input goes Low the output source drivers are disabled and the gates of the sink drivers are pulled high and left floating. This achieves optimum passive braking performance since the sink power DMOS output drivers are ON until the motor has fully completed braking. The braking control circuitry operates off the load supply (VBB) to allow it to remain operational during power loss by using the back-EMF voltage of the motor as it’s supply. LOAD SUPPLY (VBB ). This terminal is the power supply connection for the power output drivers and braking control circuitry. This terminal should be decoupled with a large-value capacitor to absorb load currents dumped back into the supply during the de-energization of motor windings. These currents can cause the supply voltage to exceed the maximum voltage rating of the device if not properly decoupled. The intrinsic ground clamp and flyback diodes will rectify the motor’s back-EMF voltage during power loss. In applications were use of the motor’s back-EMF voltage is desired a series diode should be used to isolate this terminal from the logic supply (VCC ). This is to avoid dumping the charge back into the supply and therefor clamping the voltage available from rectification of the motor’s back-EMF voltage. LOGIC SUPPLY (VCC). This is the 12 volt supply terminal for the A8925CEB and powers all circuitry except the power outputs and brake control circuitry. LOGIC GROUND. This must be connected to the power ground terminals in systems that do not use separate power and logic grounds. POWER GROUND. Terminals 7 through 17 and 29 through 39 are webbed together and attach to the die mounting area to form a low thermal resistance path to allow heat to be conducted out of the device. The power dissipation of the package can be further enhanced by soldering these terminals to a large area of copper foil on the printed wiring board. 8925 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS DIMENSIONS IN INCHES (for reference only) 18 28 29 17 0.032 0.026 0.319 0.291 0.695 0.685 0.021 0.013 0.656 0.650 0.319 0.291 0.050 INDEX AREA BSC 39 7 40 0.020 44 1 2 6 0.656 0.650 MIN 0.695 0.685 0.180 0.165 Dwg. MA-005-44A in DIMENSIONS IN MILLIMETERS (controlling dimensions) 18 28 29 17 0.812 0.661 8.10 7.39 17.65 17.40 0.533 0.331 16.662 16.510 8.10 7.39 INDEX AREA 1.27 BSC 7 39 40 0.51 MIN 4.57 4.20 44 1 2 6 16.662 16.510 17.65 17.40 Dwg. MA-005-44A mm NOTES: 1. Webbed lead frame. Leads 7 through 17 and 29 through 39 are internally one piece. 2. Exact body and lead configuration at vendor’s option within limits shown. 3. Lead spacing tolerance is non-cumulative. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 8925 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the design of its products. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. 8925 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH LINEAR CURRENT CONTROL AND POWER DMOS OUTPUTS 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000