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A4949GLJTR-T

Allegro MicroSystems LLC · Brushless DC (BLDC) Motor Driver · SOIC-8-EP

A4949GLJTR-T from Allegro MicroSystems LLC, in a SOIC-8-EP. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 GND power_in Ground reference for the device; the datasheet gives no electrical limit for this pin.
2 OUTA output Motor phase A terminal driven by the sinusoidal gate drive, with total driver RDS(on) of 1.1 Ω typical at VBB = 12 V and overcurrent limiting (IOCL) of 1.4 to 1.8 A.
3 VBB power_in Input supply, specified for 4 to 18 V with an absolute maximum rating of 18 V and undervoltage lockout at 3.85 to 3.98 V on a rising supply.
4 PWM input PWM speed input on the A4949 (VSP on the A4945), with logic high of 2 V to 5.5 V, logic low of 0 to 0.8 V, an absolute maximum of -0.3 to 6 V, an internal 100 kΩ pulldown, and a PWM frequency range of 0.1 to 100 kHz.
5 VREF power_in Analog reference output at 3.2 to 3.4 V that requires a 0.1 µF X5R 10 V ceramic capacitor (CVREF) as stated in the application circuit.
6 FG output Open-drain speed output signal that changes state once per electrical motor revolution, with a 14 V maximum voltage, 10 mA maximum current, and 0.3 V maximum saturation voltage at 5 mA.
7 OUTC output Motor phase C terminal driven by the sinusoidal gate drive, with total driver RDS(on) of 1.1 Ω typical at VBB = 12 V and overcurrent limiting (IOCL) of 1.4 to 1.8 A.
8 OUTB output Motor phase B terminal driven by the sinusoidal gate drive, with total driver RDS(on) of 1.1 Ω typical at VBB = 12 V and overcurrent limiting (IOCL) of 1.4 to 1.8 A.
9 PAD passive Exposed pad (from the footprint; not named in the datasheet pin table).

Key specifications

Parameter Value
Manufacturer Allegro MicroSystems LLC
Package SOIC-8-EP
Category Motor Driver ICs
Pins 9

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Recommended supply voltage VBB (G version valid range) VBB 4 18 V G version; electrical characteristics header 4
Supply Voltage VBB 18 V 2
Input Logic Voltage Range VIN -0.3 6 V PWM and VSP pins 2
Logic Output (FG pin) VFG 14 V FG pin 2
Logic Output Current (FG pin) IFG 10 mA FG pin 2
Operating Ambient Temperature TA -40 105 °C G temperature range 2
Maximum Junction Temperature TJ(max) 150 °C 2
Storage Temperature Tstg -55 150 °C 2
VBB Supply Current IBB 10 15 mA VIN = 3 V 4
Total Driver RDS(on) (Sink + Source) RDS(on) 1.1 1.4 Ω IOUT = 1 A, TJ = 25°C, VBB = 12 V 4
Total Driver RDS(on) (Sink + Source) RDS(on) 1.5 1.8 Ω IOUT = 1 A, TJ = 25°C, VBB = 4 V 4
Reference Voltage (VREF pin) VREF 3.2 3.3 3.4 V IFG = 5 mA 4
Output Saturation Voltage (FG Pin) VFG(sat) 0.3 V IFG = 5 mA 4
FG Output Leakage IFG(LKG) 1 µA VFG = 14 V 4
Motor PWM Frequency fOUTPWM 28 30 32 kHz 4
Input Current IIN 21 33 45 µA VIN = 3 V (RIN = 100 kΩ pulldown) 4
Logic Input (Low Level) VIL 0 0.8 V 4
Logic Input (High Level) VIH 2 5.5 V 4
Logic Input Hysteresis VIHYS 200 300 600 mV 4
PWM On Threshold DON 9.5 10 10.5 % 4
PWM Off Threshold DOFF 7 7.5 8 % 4
PWM Input Frequency Range fPWM 0.1 100 kHz 4
VBB Undervoltage Lockout (UVLO) VBBUVLO 3.85 3.98 V VBB rising 4
VBB UVLO Hysteresis VBBUVHYS 150 300 450 mV 4
Lock Protection tOFF 7 8 9 s 4
Overcurrent Limiting (OCL) IOCL 1.4 1.6 1.8 A 4
Thermal Shutdown Temperature (TSD) TJTSD 150 165 180 °C Temperature rising 4
Package Thermal Resistance (LJ package, 2-sided PCB, 0.8 in2 copper each side) RθJA 62 °C/W LJ package, 2-sided PCB with 0.8 in2 copper each side 2

Materials and finish

As the datasheet states them (page.json metadata.appearance; the 3D model's colours follow it).

Part Material Colour / plating Datasheet says Page
contacts tin for wave solder applications. Both packages are lead (Pb) free with 100% matte-tin leadframe plating. 1

CAD (KiCad official)

  • Symbol: A4949GLJTR-T
  • Footprint: Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.29x3mm
  • 3D model: SOIC-8-EP (KiCad packages3D, STEP)
  • 3D model files: a4949gljtr-t-etched.step / a4949gljtr-t-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); a4949gljtr-t.step / a4949gljtr-t.glb are the bare package body.

Provenance

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

  • Datasheet: Allegro MicroSystems LLC datasheet (12 pp, sha256 4b7c7efcaf5bd8b1, retrieved 2026-10-21, tier: lcsc)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-haiku-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF