UC3844BD1 from STMicroelectronics, in a SO-8. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	COMP	output	Error Amplifier output, made available externally for loop compensation. Typical VOH ~6.2 V with RL=15 kΩ to ground; VOL ~0.8-1.1 V with RL=15 kΩ to pin 8.
2	VFB	input	Inverting input of the internal Error Amplifier. Normally connected to the switching power supply output through a resistor divider to set the regulation loop reference (internal non-inverting input tied to 2.50 V).
3	ISENSE	input	Current-sense input. A voltage proportional to inductor/switch current is applied here; the PWM comparator uses this signal to terminate output switch conduction. Maximum input signal 1 V typical (cycle-by-cycle current limit trip point).
4	RT/CT	passive	Oscillator timing pin. Frequency and maximum output duty cycle are programmed by connecting resistor RT from VREF (pin 8) to this pin and capacitor CT from this pin to ground. Operation up to 500 kHz supported.
5	GROUND	power_in	Combined control-circuitry and power (output-stage) ground return. All voltages are referenced to this pin; use single-point grounding for timing/bypass capacitors close to this pin.
6	OUTPUT	output	Totem-pole gate-driver output for an external N-channel power MOSFET. Sources/sinks up to ±1 A peak; VOH ≥13 V at ISOURCE=20 mA, VOL ≤0.4 V at ISINK=20 mA. Held low by UVLO saturation until VCC exceeds the start threshold.
7	Vi	power_in	Positive supply (VCC) for the control IC. UVLO turn-on 16 V typ / turn-off 10 V typ for UC3844B. Absolute maximum 30 V (self-limiting via internal 36 V zener when current-fed at Ii<30 mA). Start-up current 0.3 mA typ; operating current ~12 mA.
8	VREF	power_out	Precision 5.0 V reference output, 50 mA rated. Used to supply charging current for oscillator capacitor CT through timing resistor RT and for light external loads. Short-circuit current -100 mA typical.

Key specifications

Parameter	Value
Manufacturer	STMicroelectronics
Package	SO-8
Category	Power Supply Chip
Pins	8

Ordering variants

Same part, different packaging or reel option.

UC3844BD1
UC3844BD1N

CAD (KiCad official)

Symbol: UC3844BD1
Footprint: Package_SO:TI_SO-PowerPAD-8
3D model: SO-8 (KiCad packages3D, STEP)

Provenance

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

Datasheet: STMicroelectronics datasheet (15 pp, sha256 fedfd7362400f8b3, retrieved 2026-08-17, tier: lcsc)
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