Full-bridge (H-bridge) driver for one brushed DC motor from an 8 to 40 V supply, delivering up to 3.5 A peak. Two logic inputs (IN1, IN2) set forward, reverse, brake, and coast, and a fixed off-time current-limit circuit set by VREF and a low-side sense resistor (LSS) regulates the winding current for torque control. Internal undervoltage, overcurrent, and thermal protection guard the bridge, and the exposed pad carries heat into the board. A rugged mid-voltage single-motor driver.

Pinout

Pin	Name	Type	Function
1	GND	power_in	Device ground return. Should tie to the PCB star ground located directly under the exposed thermal pad.
2	IN2	input	Logic input 2 for the full bridge. VIN(1) ≥ 2.0 V, VIN(0) ≤ 0.8 V, with internal ~50 kΩ pull-down. Combined with IN1 selects forward, reverse, brake, or coast/standby per the PWM Control Truth Table.
3	IN1	input	Logic input 1 for the full bridge. VIN(1) ≥ 2.0 V, VIN(0) ≤ 0.8 V, with internal ~50 kΩ pull-down. Both inputs low for >1 ms enters Low Power Standby mode.
4	VREF	input	Analog reference input that sets the PWM current-limit threshold. Valid range 0 to 5 V; peak trip current is ITripMAX = VREF / (10 × RS), where RS is the sense resistor on LSS.
5	VBB	power_in	Load supply voltage input, 8 to 40 V operating range (40 V absolute max). Should be decoupled with a bulk electrolytic (~100 µF) in parallel with a ceramic (~0.22 µF) close to the pin.
6	OUT1	output	DMOS full-bridge output 1 driving one side of the motor winding. Rated for up to ±3.5 A continuous (6 A transient <500 ns); absolute output voltage range −2 to 42 V.
7	LSS	passive	Low-side source / sense-resistor return. External current-sense resistor RS is connected from LSS to ground for PWM current regulation. Sense voltage limit ±500 mV.
8	OUT2	output	DMOS full-bridge output 2 driving the other side of the motor winding. Rated for up to ±3.5 A continuous (6 A transient <500 ns); absolute output voltage range −2 to 42 V.
9	PAD	passive	Exposed thermal pad on the underside of the package. Solder to the PCB copper ground plane for enhanced thermal dissipation; typically connected to GND at the star ground point.

Key specifications

Parameter	Value
Type	Full-bridge brushed DC motor driver
Supply (VBB)	8-40 V
Peak current	3.5 A
Control	IN1 / IN2 (PWM)
Current limit	Fixed off-time (VREF + LSS sense)
Protection	UVLO, OCP, thermal
Package	SOIC-8 with exposed pad

Ordering variants

A4950ELJTR-T (SOIC-8 EP)
A4950KLJTR-T (extended temp)

CAD (KiCad official)

Symbol: Driver_Motor:A4950E (KiCad official)
Footprint: Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.41x3.3mm
3D model: SOIC-8 exposed-pad (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Allegro MicroSystems datasheet (9 pp, sha256 9878d992aa310a27, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF