Low Voltage Dual DC/Stepper Motor Driver
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The A3906 is a low voltage dual full bridge motor driver designed to drive one bipolar stepper motor or two DC motors. Each output channel is rated at 1A with an operating supply voltage range of 2.5 V to 9 V. Features include fixed off time PWM current control, low on resistance DMOS outputs and peak current flag output. Output current for each full bridge can be controlled using the internal fixed off time PWM regulator or by PWM control of the two logic inputs. The current flag output is triggered when the output current reaches the trip level for the internal PWM regulator and stays on for a minimum of 300 usec. This feature is used to detect DC motor stall conditions and allows for control of the stall time for improved battery life and to prevent damage to the motor.
The output drivers are all N-channel DMOS full bridges. An internal charge pump supply will double or even triple VBB to insure proper gate drive voltage for the high and low side DMOS. The stable gate drive results in a consistent output on resistance over the full input voltage range. Protection features include thermal shutdown, under voltage lockout and crossover current protection. Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation.
The A3906 is supplied in a 4 mm x 4 mm, 20-contact QFN package with exposed thermal pad.
FEATURES AND BENEFITS
- 4 mm x 4 mm x 0.75 mm 20-contact QFN package
- Smaller package offers unique flexibility for portable designs with small form factors
- 2.5 V to 9 V operation
- Wide supply voltage range covers most battery-powered applications.
- Internal PWM current control
- Maximum output current is independent of supply voltage thereby increasing efficiency and battery life.
- Outputs rated for 1 A continuous 1.5 A peak
- (2 A continuous and 2.5 A peak with outputs paralleled)
The A3906 can be used in applications requiring high stall currents.
- (2 A continuous and 2.5 A peak with outputs paralleled)
- Peak current flag outputs
- Alerts system microprocessor that DC motor is at its maximum current so it can limit the time at this current by disabling the driver. This results in reduced motor heating and increase battery life.
- Two-stage charge pump
- Internal supply will double or even triple VBB to insure proper gate drive voltage. This results in stable DMOS Rds(on) over the full operating voltage range.
- Less than 150 nA typical sleep mode current
- Low sleep current reduces battery drain and extends operating time
- Synchronous rectification
- Reduces IC power dissipation during PWM operation. Results in lower temperature rise in the IC so it can operate over a wider temperature range and at higher average current. This improved IC efficiency can result in longer battery life.