The A8904SLB and A8904SLP are three-phase brushless dc motor controller/drivers designed for applications where accurate control of highspeed motors is required. The three half-bridge outputs are low on-resistance n-channel DMOS devices capable of driving up to 1.2 A. The A8904 provides complete, reliable, self-contained back-EMF sensing, motor startup and running algorithms. A programmable digital frequency-locked loop speed control circuit together with the linear current control circuitry provides precise motor speed regulation.
A serial port allows the user to program various features and modes of operation, such as the speed control parameters, startup current limit, sleep mode, direction, and diagnostic modes.
The A8904 is fabricated in Allegro's BCD (Bipolar CMOS DMOS) process, an advanced mixed-signal technology that combines bipolar, analog and digital CMOS, and DMOS power devices. The A8904SLB is provided in a 24-lead wide-body SOIC batwing package. The A8904SLP is provided in a thin (<1.2 mm), 28-lead SSOP package with an exposed thermal pad. Each package type is available in a lead-free version (100% matte tin leadframe).
Load Supply Voltage, VBB . . . . . . . . . . . . . . . 15 V
Output Current1, IOUT . . . . . . . . . . . . . . . .±1.4 A
Peak Output Current (Brake)2, IOUT(BRK) . ±3.0 A
Period2 for IOUT(BRK) to fall from
±3.0 A to ±1.4 A . . . . . . . . . . . . . . . . . .800 ms
Logic Supply Voltage, VDD . . . . . . . . . . . . . . 7.0 V
Logic Input Voltage Range, VIN
(continuous) . . . . . . . . . . .-0.3 V to VDD + 0.3 V
(tw <30 ns) . . . . . . . . . . . .-1.0 V to VDD + 1.0 V
Package Power Dissipation, PD . . . . . . See Graph
Operating Temperature, TA . . . . -20°C to +85°C
Junction Temperature3, TJ . . . . . . . . . . . .+150°C
Storage Temperature,TS . . . . . .-55°C to +150°C
1 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.
2 Peak output current is a transient condition that occurs during braking when the motor acts as a generator. The 3 A level is based on the maximum peak of a sine wave that is damped. The maximum period between the initial brake being applied and the current through the drivers falling to 1.4 A should not exceed 800 ms. See Braking section for more information.
3 Fault conditions that produce excessive junction temperature will activate device thermal shutdown circuitry. These conditions can be tolerated, but should be avoided.
Required Field 
