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UC2845B

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by Ray

UMW AC-DC Controllers and Regulators, SOP-8. Datasheet-verified pinout, KiCad symbol/footprint/3D.

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Contents

README

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UC2845B

UMW · AC-DC Controllers and Regulators · SOP-8

UC2845B from UMW, in a SOP-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, used for loop compensation. External compensation network (typically an RC to VFB) is tied here to shape the control-loop response.
2 VFB input Inverting input of the internal Error Amplifier. Normally tied to the switching-power-supply output through a resistor divider so that the loop regulates VFB to the internal 2.5 V reference.
3 ISENSE input Current-sense input. A voltage proportional to the inductor/switch current (typically from a sense resistor) is applied here; the PWM comparator uses it to terminate each output switch cycle. Internal current-sense comparator trips at ~1 V.
4 RT/CT passive Oscillator timing pin. Connect resistor RT from VREF (pin 8) to this pin and capacitor CT from this pin to ground to program oscillator frequency and maximum output duty cycle. Can also accept an external sync input.
5 GND power_in Combined control-circuit and power ground return for the IC. All external timing, sense, and bypass components reference this pin.
6 OUTPUT output High-current totem-pole gate-drive output. Directly drives the gate of an external power MOSFET; sources and sinks peak currents up to 1 A. Output is held low during UVLO.
7 VCC power_in Positive supply pin for the IC (also referred to as POWER VCC in the block diagram). Absolute max 30 V; internal 36 V zener clamp. UVLO turn-on 8.4 V typ, turn-off 7.6 V typ for the UC2845B; operating supply current ~13 mA (17 mA max).
8 VREF power_out Trimmed 5 V (±1%) reference output. Supplies charging current for the timing capacitor CT through timing resistor RT, and can source current to external circuitry (short-circuit current typ -100 mA).

Key specifications

Parameter Value
Manufacturer UMW
Package SOP-8
Category PMIC
Pins 8

Ordering variants

Same part, different packaging or reel option.

  • UC2845BUMW UC2845B

CAD (KiCad official)

  • Symbol: UC2845B
  • Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
  • 3D model: SOP-8 (KiCad packages3D, STEP)

Provenance

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

  • Datasheet: UMW datasheet (13 pp, sha256 d748ab15bdd235a3, 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