component

UC3843BD1G

Public Made by Adom

by adom

onsemi DC-DC Controllers, SOIC-8. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.

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UC3843BD1G

onsemi · DC-DC Controllers · SOIC-8

UC3843BD1G from onsemi, in a SOIC-8. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 Compensation output Error amplifier output made available for loop compensation; rated -0.3 to +7.2 V with 10 mA maximum error amp sink current.
2 Voltage Feedback input Inverting input of the error amplifier, normally connected to the switching power supply output through a resistor divider; rated -0.3 to +5.5 V.
3 Current Sense input Receives a voltage proportional to inductor current, which the PWM uses to terminate output switch conduction; rated -0.3 to +5.5 V.
4 RT/CT passive Oscillator frequency and maximum output duty cycle are set by resistor RT to Vref and capacitor CT to ground, with operation to 500 kHz possible.
5 GND power_in Combined control circuitry and power ground.
6 Output output Directly drives the gate of a power MOSFET, sourcing and sinking peak currents up to 1.0 A.
7 VCC power_in Positive supply of the control IC; maximum rating 30 V.
8 Vref power_out Reference output (5.0 V block) that provides charging current for capacitor CT through resistor RT.

Key specifications

Parameter Value
Manufacturer onsemi
Package SOIC-8
Category Power Management ICs
Pins 8

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Reference Output Voltage Vref 4.9 5 5.1 V IO = 1.0 mA, TJ = 25°C 3
Line Regulation Regline 2 20 mV VCC = 12 V to 25 V 3
Load Regulation Regload 3 25 mV IO = 1.0 mA to 20 mA 3
Total Output Variation over Line, Load, Temperature Vref 4.82 5.18 V 3
Output Short Circuit Current ISC -30 -85 -180 mA 3
Oscillator Frequency fOSC 49 52 55 kHz TJ = 25°C 3
Oscillator Frequency over temperature fOSC 48 56 kHz TA = Tlow to Thigh 3
Oscillator Frequency fOSC 225 250 275 kHz TJ = 25°C (RT = 6.2 k, CT = 1.0 nF) 3
Frequency Change with Voltage fOSC/V 0.2 1 % VCC = 12 V to 25 V 3
Discharge Current Idischg 7.8 8.3 8.8 mA VOSC = 2.0 V, TJ = 25°C 3
Discharge Current over temperature Idischg 7.6 8.8 mA VOSC = 2.0 V, TA = Tlow to Thigh 3
Voltage Feedback Input VFB 2.42 2.5 2.58 V VO = 2.5 V 3
Error Amp Input Bias Current IIB -0.1 -2 µA VFB = 5.0 V 3
Open Loop Voltage Gain AVOL 65 90 dB VO = 2.0 V to 4.0 V 3
Unity Gain Bandwidth BW 0.7 1 MHz TJ = 25°C 3
Error Amp PSRR PSRR 60 70 dB VCC = 12 V to 25 V 3
Error Amp Output Sink Current ISink 2 12 mA VO = 1.1 V, VFB = 2.7 V 3
Error Amp Output Source Current ISource -0.5 -1 mA VO = 5.0 V, VFB = 2.3 V 3
Error Amp Output Voltage High VOH 5 6.2 V RL = 15 k to ground, VFB = 2.3 V 3
Error Amp Output Voltage Low VOL 0.8 1.1 V RL = 15 k to Vref, VFB = 2.7 V 3
Current Sense Input Voltage Gain AV 2.85 3 3.15 V/V 4
Maximum Current Sense Input Threshold Vth 0.9 1 1.1 V 4
Current Sense Input Bias Current IIB -2 -10 µA 4
Propagation Delay (Current Sense to Output) tPLH(In/Out) 150 300 ns 4
Output Voltage Low State VOL 0.1 0.4 V ISink = 20 mA 4
Output Voltage Low State VOL 1.6 2.2 V ISink = 200 mA 4
Output Voltage High State VOH 13 13.5 V ISource = 20 mA 4
Output Voltage High State VOH 12 13.4 V ISource = 200 mA 4
Output Voltage with UVLO Activated VOL(UVLO) 0.1 1.1 V VCC = 6.0 V, ISink = 1.0 mA 4
Output Voltage Rise Time tr 50 150 ns CL = 1.0 nF, TJ = 25°C 4
Output Voltage Fall Time tf 50 150 ns CL = 1.0 nF, TJ = 25°C 4
Startup Threshold (VCC) UCX843B Vth 7.8 8.4 9 V 4
Minimum Operating Voltage After Turn-On (VCC) UCX843B VCC(min) 7 7.6 8.2 V 4
Maximum Duty Cycle DC(max) 94 96 % 4
Minimum Duty Cycle DC(min) 0 % 4
Power Supply Current Startup ICC + IC 0.3 0.5 mA VCC = 6.5 V for UCX843B 4
Power Supply Current Operating ICC + IC 12 17 mA 4
Power Supply Zener Voltage VZ 30 36 V ICC = 25 mA 4
Bias and Driver Voltage VCC, VC 30 V Zero series impedance 2
Total Power Supply and Zener Current ICC + IZ 30 mA 2
Output Current, Source or Sink IO 1 A 2
Output Energy (Capacitive Load per Cycle) W 5 J 2
Current Sense, Voltage Feedback, Vref and Rt/Ct Input Voltage Vin -0.3 5.5 V 2
Compensation Voltage Vcomp -0.3 7.2 V 2
Output Voltage Vo -0.3 V Max is VCC or VC + 0.3 2
Error Amp Output Sink Current IO 10 mA 2
Power Dissipation SOIC-8 D1 PD 702 mW TA = 25°C 2
Thermal Resistance Junction-to-Air SOIC-8 D1 RθJA 178 °C/W 2
Operating Junction Temperature TJ 150 °C 2
Operating Ambient Temperature TA 0 70 °C UC3843B 2
Storage Temperature Range Tstg -65 150 °C 2
ESD Human Body Model 4000 V JESD22-A114B (exceeds) 2
ESD Machine Model 200 V JESD22-A115-A (exceeds) 2
Temperature Stability TS 0.2 mV/°C 3
Frequency Change with Temperature fOSC/T 0.5 % TA = Tlow to Thigh 3
Oscillator Voltage Swing (Peak-to-Peak) VOSC 1.6 V 3

CAD (KiCad official)

  • Symbol: UC3843BD1G
  • Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
  • 3D model: SOIC-8 (KiCad packages3D, STEP)
  • 3D model files: uc3843bd1g-etched.step / uc3843bd1g-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); uc3843bd1g.step / uc3843bd1g.glb are the bare package body.

Provenance

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

  • Datasheet: onsemi datasheet (25 pp, sha256 73603e023e6d2fe7, retrieved 2026-10-23, tier: manufacturer)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-sonnet-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF