The A4987 is a dual DMOS with parallel input communication and overcurrent protectionFull-bridge stepper motor driver。 Each full-bridge output is rated at 35 V and ±1 A. The A4987 features a fixed downtime impulse width modulation (PWM) current regulator and a 2-bit nonlinear DAC (Digital-to-analog converters), allowing full, 1/2 and 1/4 step control of stepper motors. PWM current regulators use Allegro's® patented hybrid attenuation mode to reduce audible motor noise, increase step accuracy, and reduce power dissipation.
Internal synchronous rectification control circuitry is provided to improve power consumption during pulse-width modulation (PWM) operation.
Short-circuit load and ground protection is provided to the output to protect the driver and associated circuitry from thermal damage or burnout. Other protection features include thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover current protection. No special power-on sequencing is required.
The A4987 is available in two packages: 24-contact QFN (ES) and 24-pin TSSOP (LP). Both packages have exposed heat sinks for enhanced thermal performance. The 24-contact ES is available in 4 mm × 4 mm packages with a nominal overall package height of 0.75 mm. The 24-pin LP is a TSSOP package with 0.65 clearance and an overall package height of ≤1.2 mm. Both packages are lead (Pb) free and feature 100% matte tin leadframe plating.
- Low RDS (ON) output
- Internal hybrid current attenuation mode
- Synchronous rectification for low power dissipation
- Internal UVLO
- Crossover current protection
- 3.3 and 5 V compatible logic supplies
- Ultra-thin QFN and TSSOP packages
- Thermal shutdown circuit
- Short-to-ground protection
- Load short-circuit protection
- Low current sleep mode,