UC3845BN from STMicroelectronics, in a DIP-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 for loop compensation. Typically an RC network is connected between this pin and VFB (pin 2) to shape the control-loop response.
2	VFB	input	Inverting input of the internal error amplifier. Normally connected to the switching power supply output through a resistor divider; the non-inverting input is internally tied to the 2.5 V reference.
3	ISENSE	input	Current-sense input. A voltage proportional to the primary/inductor current is applied here; the PWM comparator terminates the output switch conduction when this pin reaches the error-amp-derived threshold (max input signal ~1 V, gain 3 V/V).
4	RT/CT	passive	Oscillator timing pin. A resistor RT from this pin to VREF and a capacitor CT from this pin to GROUND set the oscillator frequency and the maximum output duty cycle. Operation up to 500 kHz is possible.
5	GROUND	power_in	Common control-circuitry and power-stage return. All voltages in the datasheet are referenced to this pin; timing and bypass capacitors must connect close to this pin in a single-point ground.
6	OUTPUT	output	High-current totem-pole gate-drive output for an external N-channel power MOSFET. Peak source/sink currents up to 1 A; typical rise/fall times ~50 ns into 1 nF.
7	VCC	power_in	Positive supply of the control IC (labeled Vi in the block diagram/absolute-maximum table). Max 30 V (self-limiting via internal ~36 V zener). UVLO turn-on 8.5 V typ, turn-off 7.9 V typ; operating supply current ~12 mA typ.
8	VREF	power_out	Buffered 5.0 V reference output (5 V, 50 mA capable). Provides charging current for the timing capacitor CT through the timing resistor RT and can bias external circuitry.

Key specifications

Parameter	Value
Manufacturer	STMicroelectronics
Package	DIP-8
Category	PMIC
Pins	8

Ordering variants

Same part, different packaging or reel option.

UC3845BNN
UC3845BND1

CAD (KiCad official)

Symbol: UC3845BN
Footprint: Package_DIP:DIP-8_W7.62mm
3D model: DIP-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`uc3845bn.step`	271 KB	You want the bare part, or you mark your own boards.
`uc3845bn-etched.step`	2.1 MB	You want the part with `UC3845BN` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 502 faces against 148 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: STMicroelectronics datasheet (15 pp, sha256 62066370bcc6f048, 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