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UC3842BL-S08-R

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

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UC3842BL-S08-R

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

UC3842BL-S08-R from UTC Unisonic Tech, 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 COMP output Error amplifier output that provides loop compensation to maintain VFB at 2.5V.
2 VFB input Error amplifier inverting input; the non-inverting input is the internal 2.5V bandgap reference.
3 CS input Current sense input to the PWM control gate drive of the output; raising it above 1V shuts down the output, and the Current Sense and Voltage Feedback inputs are rated -0.3 V to +5.5 V.
4 RTCT input Sets the oscillator frequency and the maximum output duty cycle through the RT and CT timing components.
5 GND power_in Power ground; the timing and bypass capacitors must be connected to this pin at a single close point.
6 OUTPUT output Drives the power MOSFET directly; the datasheet recommends a bleeder resistor from this pin to ground to prevent false turn-on from leakage during undervoltage lockout.
7 VCC power_in Power supply input; the UC3842B UVLO thresholds are 16V (on) and 10V (off), and the UC3843B thresholds are 8.4V (on) and 7.6V (off).
8 VREF power_out Regulated 5V output (4.9 V to 5.1 V at IO = 1.0 mA, TJ = 25°C) that supplies the charging current for CT through RT.

Key specifications

Parameter Value
Manufacturer UTC Unisonic Tech
Package SOIC-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
Output Voltage VREF 4.9 5 5.1 V IO=1.0mA, TJ=25℃ 3
Total Output Variation VREF 4.82 5.18 V Line, Load, Temperature 3
Line Regulation ΔVLINE 2 20 mV VCC=12V ~ 25V 3
Load Regulation ΔVLOAD 3 25 mV IO=1.0mA ~ 20mA 3
Output Short Circuit Current ISC -30 -85 -180 mA 3
Oscillator Frequency F 49 52 55 kHz TJ=25℃ 3
Oscillator Frequency F 48 56 kHz TA=0℃ ~ 70℃ 3
Oscillator Frequency F 225 250 275 kHz TJ=25℃ (RT=6.2k,CT=1.0nF) 3
Frequency Change with Voltage ΔfOSC/ΔV 0.2 1 % 12 ≤ VCC ≤25V 3
Discharge Current IDISCHG 7.8 8.3 8.8 mA TJ=25℃ 3
Discharge Current IDISCHG 7.6 8.3 8.8 mA 0℃ ≤TA≤70℃ 3
Voltage Feedback Input VFB 2.42 2.5 2.58 V Vo=2.5V 4
Input Bias Current II(BIAS) -0.1 -2 μA VFB=5.0V 4
Open Loop Voltage Gain GVO 65 90 dB 2 ≤VO≤4V 4
Unity Gain Bandwidth GBW 0.7 1 MHz TJ=25℃ 4
Power Supply Rejection Ratio PSRR 60 70 dB I2V≤VCC≤25V 4
Output Sink Current ISINK 2 12 mA VO=1.1V,VFB=2.7V 4
Output Source Current ISOURCE -0.5 -1 mA VO=5.0V,VFB=2.3V 4
Output Voltage Swing High State VOH 5 6.2 V VFB=2.3V, RL=15k to GND 4
Output Voltage Swing Low State VOL 0.8 1.1 V VFB=2.7V, RL=15k to VREF 4
Current Sense Input Voltage Gain GV 2.85 3 3.15 V/V Note 2, 3 4
Maximum Current Sense Input Threshold VI(THR) 0.9 1 1.1 V Note 2 4
Input Bias Current (Current Sense) II(BIAS) -2 -10 μA 4
Propagation Delay tD(IN/OUT) 150 300 ns Current Sense Input to Output 4
Output Low Voltage VOL 0.1 0.4 V ISINK=20mA 4
Output Low Voltage VOL 1.6 2.2 V ISINK=200mA 4
Output High Voltage VOH 13 13.5 V ISOURCE=20mA 4
Output High Voltage VOH 12 13.4 V ISOURCE=200mA 4
Output Voltage with UVLO Activated VOL (UVLO) 0.1 1.1 V VCC=6.0V, ISINK=1.0mA 4
Output Voltage Rise Time tR 50 150 ns TJ=25℃, CL=1nF 4
Output Voltage Fall Time tF 50 150 ns TJ=25℃, CL=1nF 4
Startup Threshold (UC3842B) VTHR 14.5 16 17.5 V UC3842B 4
Min. Operating Voltage After Turn-on (UC3842B) VCC(MIN) 8.5 10 11.5 V UC3842B 4
Duty Cycle MAX MAX DC 94 96 % 4
Power Startup Supply Current ICC+IC 0.3 0.5 mA VCC=14V for UC3842B 4
Power Operating Supply Current ICC+IC 12 17 mA Note 1 4
Power Supply Zener Voltage VZ 30 36 V ICC=25mA 4
Total Power Supply and Zener Current ICC + IZ 30 mA 3
Output Current, Source or Sink IO 1 A Note 2 3
Output Energy W 5 μJ Capacitive load per cycle 3
Current Sense and Voltage Feedback Inputs VIN -0.3 5.5 V 3
Error Amp Output Sink Current IO(SINK) 10 mA 3
Power Dissipation PD 800 mW SOP-8 3
Operating Junction Temperature TJ 150 ℃ 3
Operating Temperature TOPR 0 70 ℃ 3
Storage Temperature TSTG -65 150 ℃ 3
Junction to Ambient (SOP-8) θJA 156 °C/W SOP-8 3

CAD (KiCad official)

  • Symbol: UC3842BL-S08-R
  • Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
  • 3D model: SOIC-8 (KiCad packages3D, STEP)
  • 3D model files: uc3842bl-s08-r-etched.step / uc3842bl-s08-r-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); uc3842bl-s08-r.step / uc3842bl-s08-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 2026-10-20, 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