UC3843BVD1R2G from onsemi, in a SOIC-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	Compensation	output	Error Amplifier output, made available for external loop compensation. Voltage on this pin sets the peak inductor current (Ipk = (V_pin1 − 1.4 V) / (3·Rs)); internally clamped to ~1.0 V during overload.
2	Voltage Feedback	input	Inverting input of the Error Amplifier. Normally connected to the switching supply output through a resistor divider; the non-inverting input is internally biased to 2.5 V. Input bias current is typically −0.1 µA (max −2.0 µA).
3	Current Sense	input	Current-sense input; a voltage proportional to inductor current is applied here. The PWM uses this information to terminate output switch conduction on a cycle-by-cycle basis. Maximum input threshold typically 1.0 V; current sense gain Av ≈ 3.0 V/V.
4	RT/CT	passive	Oscillator timing pin. The oscillator frequency and maximum duty cycle are programmed by connecting timing resistor RT from Vref to this pin and capacitor CT from this pin to ground. Operation to 500 kHz is possible; sawtooth swings between ~1.2 V (valley) and ~2.8 V (peak).
5	GND	power_in	Combined control-circuitry and power ground return for the 8-pin package. All internal grounds and the output stage return through this pin.
6	Output	output	High-current totem-pole gate-drive output for driving a power MOSFET. Peak source/sink currents up to 1.0 A; rise/fall times ~50 ns typical into 1 nF. Output is held low when UVLO is active.
7	VCC	power_in	Positive supply of the control IC. UC3843B startup threshold 8.4 V typ (7.8-9.0 V), min operating voltage after turn-on 7.6 V typ. Absolute maximum 30 V; internal zener clamps at 36 V typ.
8	Vref	power_out	5.0 V trimmed reference output (typ 5.0 V, ±1% at TJ = 25°C, IO = 1 mA). Provides charging current for CT through RT and can source up to ~50 mA to external loads; short-circuit current limited to ~85 mA.

Key specifications

Parameter	Value
Manufacturer	onsemi
Package	SOIC-8
Category	PMIC
Pins	8

Ordering variants

Same part, different packaging or reel option.

UC3843BVD1R2G
UC3843BVD1R2GD1G
UC3843BVD1R2GN
UC3843BVD1R2GNG
UC3843BVD1R2GD
UC3843BVD1R2GDG
UC3843BVD1R2GDR2
UC3843BVD1R2GDR2G

CAD (KiCad official)

Symbol: UC3843BVD1R2G
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOIC-8 (KiCad packages3D, STEP)

Provenance

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

Datasheet: onsemi datasheet (22 pp, sha256 581ae31fbd1f3e07, 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