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UC3845BM

Public Made by Adom

by adom

HGSEMI AC-DC Controllers And Regulators, SOP-8. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.

componentpower management (pmic)uc3845bmfactory-2.0.0extractor-text
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Contents

README

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UC3845BM

HGSEMI · AC-DC Controllers And Regulators · SOP-8

UC3845BM from HGSEMI, in a SOP-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 COMP output This pin is the Error Amplifier output and is made for loop compensation, with an absolute maximum error amplifier output sink current (ISINK(E.A)) of 10 mA.
2 VFB input This is the inverting input of the Error Amplifier, normally connected to the switching power supply output through a resistor divider, with a specified input voltage (VI(E.A)) of 2.42 V to 2.58 V (2.5 V typ) at Vpin1 = 2.5 V.
3 ISENSE input A voltage proportional to inductor current is connected to this input, which the PWM uses to terminate the output switch conduction; analog inputs (pins 2, 3) are rated from -0.3 V to 5.5 V, with a maximum input signal (VI(MAX)) of 0.9 V to 1.1 V (1.0 V typ).
4 RT/CT passive The oscillator frequency and maximum output duty cycle are programmed by connecting resistor RT to Vref and capacitor CT to ground.
5 GROUND power_in This pin is the combined control circuitry and power ground.
6 OUTPUT output This output directly drives the gate of a power MOSFET, sourcing and sinking peak currents up to 1 A.
7 VCC power_in This pin is the positive supply of the integrated circuit, with an absolute maximum supply voltage of 30 V from a low impedance source.
8 Vref power_out This is the reference output that provides charging current for capacitor CT through resistor RT, specified at 4.9 V to 5.1 V (5.0 V typ) at TJ = 25°C and IREF = 1 mA.

Key specifications

Parameter Value
Manufacturer HGSEMI
Package SOP-8
Category Power Management (PMIC)
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 TJ = 25°C, IREF = 1 mA 3
Line Regulation ΔVREF 6 20 mV 12V ≤ VCC ≤ 25 V 3
Load Regulation ΔVREF 6 25 1 mA ≤ IREF ≤ 20mA 3
Short Circuit Output Current ISC -100 -180 mA TA = 25°C 3
Oscillation Frequency f 47 52 57 KHz TJ = 25°C 3
Frequency Change with Voltage Δf/ΔVCC 0.05 1 % 12V ≤ VCC ≤ 25 V 3
Error Amplifier Input Bias Current IBIAS -0.1 -2 µA VFB=3V 3
Error Amplifier Input Voltage VI(E.A) 2.42 2.5 2.58 V Vpin1 = 2.5V 3
Open Loop Voltage Gain AVOL 65 90 dB 2V ≤ V0 ≤ 4V 3
Unity Gain Bandwidth UGBW 0.5 0.6 MHz Tj=25°C, Note 3 3
Power Supply Rejection Ratio PSRR 60 70 dB 12V ≤ VCC ≤ 25 V 3
Output Sink Current ISINK 2 7 mA Vpin2 = 2.7V, Vpin1 = 1.1V 3
Output Source Current ISOURCE -0.5 -1 mA Vpin2 = 2.3V, Vpin1 = 5V 3
Error Amplifier High Output Voltage VOH 5 6 V Vpin2 = 2.3V, RL = 15KΩ to GND 3
Error Amplifier Low Output Voltage VOL 0.8 1.1 V Vpin2 = 2.7V, RL = 15KΩ to PIN 8 3
Current Sense Gain GV 2.85 3 3.15 V/V Note 1 & 2 3
Maximum Input Signal VI(MAX) 0.9 1 1.1 V Vpin1 = 5V (Note 1) 3
Current Sense Input Bias Current IBIAS -3 -10 µA Vpin3 = 3V 3
Output Low Voltage VOL 0.08 0.4 V ISINK = 20 mA 3
Output Low Voltage VOL 1.4 2.2 V ISINK = 200 mA 3
Output High Voltage VOH 13 13.5 V ISINK = 20 mA 3
Output High Voltage VOH 12 13 V ISINK = 200 mA 3
Rise Time tR 45 150 nS TJ = 25°C, CL = 1nF (Note 3) 3
Fall Time tF 35 150 nS TJ = 25°C, CL = 1nF (Note 3) 3
Start Threshold Voltage VTH(ST) 7.8 8.4 9 V UC3843B,UC3845B 3
Minimum Operating Voltage (After Turn On) VOPR(min) 7 7.6 8.2 V UC3843B,UC3845B 3
Maximum Duty Cycle D(MAX) 47 48 50 % UC3844B,UC3845B 3
Minimum Duty Cycle 0 3
Start-Up Current IST 0.17 0.3 mA UC3842B/43B/44B/45B 3
Operating Supply Current ICC (OPR) 13 17 mA Vpin3 = Vpin2 = 0V 3
Zener Voltage VZ 30 38 V ICC=25 mA 3
Supply Voltage (low impedance source) VCC 30 V 2
Output Current IO -1 1 A 2
Input Voltage (Analog Inputs pins 2,3) VI -0.3 5.5 V 2
Error Amp Output Sink Current ISINK (E.A) 10 mA 2
Power Dissipation PO 1 W TA=25°C 2
Storage Temperature Range Tstg -65 150 °C 2
Lead Temperature TL 260 °C soldering 5 sec. 2
Operating Ambient Temperature TA -40 85 °C characterized for operation 1

CAD (KiCad official)

  • Symbol: UC3845BM
  • Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
  • 3D model: SOP-8 (KiCad packages3D, STEP)
  • 3D model files: uc3845bm-etched.step / uc3845bm-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); uc3845bm.step / uc3845bm.glb are the bare package body.

Provenance

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

  • Datasheet: HGSEMI datasheet (11 pp, sha256 27376c62601f1c47, retrieved 2026-10-18, tier: lcsc)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-haiku-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