component
A4950
Public Made by Adomby adom
Allegro full-bridge brushed DC motor driver, SOIC-8 with exposed pad. 8-40 V, 3.5 A peak, current limit. Datasheet-verified.
3D Model
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Symbol & Footprint
Schematic Symbol
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PCB Footprint
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Datasheet
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README
markdownA4950
Allegro MicroSystems · Brushed DC motor driver · SOIC-8-EP
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)
- 3D model files:
a4950-etched.step/a4950-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);a4950.step/a4950.glbare the bare package body.
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).