UC3842BD1R2G 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 loop compensation. External compensation network is tied between this pin and the Voltage Feedback input (pin 2).
2	Voltage Feedback	input	Inverting input of the error amplifier. Normally connected to the switching power supply output through a resistor divider; nominal reference at this node is 2.5 V.
3	Current Sense	input	Non-inverting input of the current-sense comparator. A voltage proportional to inductor/switch current is applied here; peak current-sense threshold is typically 1.0 V (max) for cycle-by-cycle limiting.
4	RT/CT	passive	Oscillator timing pin. An external resistor to Vref and a capacitor to ground set the oscillator frequency and maximum output duty cycle. Guaranteed oscillator frequency up to 250 kHz; operational to 500 kHz.
5	GND	power_in	Device ground and return for both control-signal and high-current output-driver return paths (single-ground SOIC-8 / PDIP-8 variant).
6	Output	output	High-current totem-pole PWM gate-drive output for directly driving a power MOSFET. Rated 1.0 A source/sink; typical rise/fall times of 50 ns into 1.0 nF.
7	VCC	power_in	Positive supply voltage for control logic and output driver. UC3842B UVLO turn-on at 16 V (typ) and turn-off at 10 V (typ); maximum rating 30 V. Internal 36 V zener clamp (ICC = 25 mA).
8	Vref	power_out	Trimmed and temperature-compensated 5.0 V reference output. Typically capable of sourcing 20 mA to external circuitry and provides the pull-up for the RT/CT oscillator resistor. Short-circuit current limited to approximately 85 mA (typ).

Key specifications

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

Ordering variants

Same part, different packaging or reel option.

UC3842BD1R2G
UC3842BD1R2GD1G
UC3842BD1R2GN
UC3842BD1R2GNG
UC3842BD1R2GD
UC3842BD1R2GDG
UC3842BD1R2GDR2G

CAD (KiCad official)

Symbol: UC3842BD1R2G
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOIC-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`uc3842bd1r2g.step`	122 KB	You want the bare part, or you mark your own boards.
`uc3842bd1r2g-etched.step`	2.8 MB	You want the part with `UC3842BD1R2G` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 678 faces against 147 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

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