These parts are in production but have been determined to be NOT FOR NEW DESIGN. This classification indicates that sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because obsolescence in the near future is probable. Samples are no longer available. Date of status change: May 4, 2009.
Features
- Pin-for-pin replacement for A8902CLBA
- Start-up commutation circuitry
- Sensorless commutation circuitry
- Option of external sector data tachometer signal
- Option of external speed control
- Oscillator operation up to 20 MHz
- Programmable overcurrent limit
- Transconductance gain options: 500 mA/V or 250 mA/V
- Programmable watchdog timer
- Directional control
- Serial port interface
- TTL-compatible inputs
- System diagnostics data-out ported in real time
- Dynamic braking through serial port or external terminal
Description
The A8904 is a 3-phase brushless DC motor controller/driver designed for applications where accurate control of high-speed 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 start-up, 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, start-up current limit, sleep mode, direction, and diagnostic modes.
The A8904 is fabricated in the Allegro® BCD (Bipolar CMOS DMOS) process, an advanced mixed-signal technology that combines bipolar, analog, and digital CMOS, with DMOS power devices.
The device is provided in a 24-pin wide-body SOIC package, with 4 internally-fused leads for enhanced thermal dissipation (package LB), and a thin (<1.2 mm overall height), 28-pin TSSOP package with an exposed thermal pad Package LP). Both packages are lead (Pb) free, with 100% matte tin leadframe plating.
Functional Block Diagram
