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UC3843BP-SO8-R

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UTC Unisonic Tech AC-DC Controllers and Regulators, SOIC-8. Datasheet-verified pinout, KiCad symbol/footprint/3D.

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Contents

README

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UC3843BP-SO8-R

UTC Unisonic Tech · AC-DC Controllers and Regulators · SOIC-8

UC3843BP-SO8-R from UTC Unisonic Tech, 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 COMP output Error amplifier output. Used for loop compensation via an external Z_F network between COMP and VFB; the error amp maintains VFB at the internal 2.5V band-gap reference. Can also be pulled below ~2 diode drops above GND to shut down the PWM.
2 VFB input Error amplifier inverting input. Regulated against the internal 2.5V band-gap reference on the non-inverting input; the feedback divider from the converter output is tied here.
3 CS input Current sense input to the PWM comparator. Sets peak switch current per I_S(MAX) = 1.0V / R_S; input threshold is 1.0V typical. Also serves as a shutdown input when raised above 1V. A small RC filter is recommended to suppress leading-edge switching transients.
4 RT/CT passive Oscillator timing node. An external R_T from VREF to this pin and C_T from this pin to GND set the oscillator frequency and maximum output duty cycle. C_T charges through R_T from VREF and discharges via an internal ~8.3mA current source.
5 GND power_in Device power and signal ground. Timing and bypass capacitors must return to this pin at a single-point ground.
6 OUTPUT output High-current totem-pole gate-drive output for direct drive of a power MOSFET. Rated to 1.0A source/sink peak; typical rise/fall time 50ns into 1nF. Held low during UVLO; a bleeder resistor to GND is recommended to prevent leakage-driven turn-on of the external switch.
7 VCC power_in Positive supply input. UC3843B UVLO turn-on threshold 8.4V typ (7.8-9V), turn-off 7.6V typ (7.0-8.2V). Internal 36V shunt zener clamps VCC at I_CC=25mA. Typical operating supply current ~12mA; startup current <0.5mA below UVLO.
8 VREF power_out Trimmed 5.0V reference output (4.9-5.1V at I_O=1mA). Supplies the oscillator timing resistor R_T and can source external loads; short-circuit current limited to ~-85mA typical. Bypass to GND with 0.1uF close to the pin.

Key specifications

Parameter Value
Manufacturer UTC Unisonic Tech
Package SOIC-8
Category PMIC
Pins 8

Ordering variants

Same part, different packaging or reel option.

  • UC3843BP-S08-R
  • UC3843BP-S08-T
  • UC3843BL-S08-R
  • UC3843BL-S08-T
  • UC3843BP-D08-T
  • UC3843BL-D08-T
  • UC3842BP-S08-R
  • UC3842BP-S08-T
  • UC3842BL-S08-R
  • UC3842BL-S08-T
  • UC3842BP-D08-T
  • UC3842BL-D08-T

CAD (KiCad official)

  • Symbol: UC3843BP-SO8-R
  • Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
  • 3D model: SOIC-8 (KiCad packages3D, STEP)
  • 3D model files: uc3843bp-so8-r-etched.step / uc3843bp-so8-r-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); uc3843bp-so8-r.step / uc3843bp-so8-r.glb are the bare package body.

Provenance

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

  • Datasheet: UTC Unisonic Tech datasheet (10 pp, sha256 78a2af3e18258f77, 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