# UC3842M

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

UC3842M 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 | Output of the error amplifier, which can be used for loop compensation. |
| 2 | VFB | input | Inverting input of the error amplifier, normally connected to the switching supply through a resistor divider; the internal reference on the non-inverting side is 2.5 V (Vfb 2.42 V to 2.58 V). |
| 3 | ISENSE | input | Voltage proportional to the inductor coil current is applied here, and the PWM turns the output off when the voltage on this pin reaches the threshold; maximum input signal is 0.9 V to 1.1 V and absolute input range is -0.3 V to 5.5 V. |
| 4 | RT/CT | passive | RT is connected to VREF and CT to ground to set the oscillator frequency and maximum duty cycle, with frequency up to 500 kHz. |
| 5 | GND | power_in | Ground reference for the controller. |
| 6 | OUTPUT | output | Drives the gate of the power MOSFET directly, sourcing or sinking peak currents up to 1 A. |
| 7 | VCC | power_in | Positive supply for the control IC; the absolute maximum supply voltage is 30 V, with undervoltage lockout start at 16 V (typ.) and minimum operating voltage 10 V (typ.). |
| 8 | VREF | power_out | Reference voltage output (5.0 V typ., 4.90 V to 5.10 V at Tj = 25 °C, 1 mA load) that charges timing capacitor CT through resistor RT. |

## 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 |
|---|---|---|---|---|---|---|---|
| 电源电压 | Vcc |  |  | 30 | V |  | 3 |
| 输出电流 | Io | -1 |  | 1 | A |  | 3 |
| 输出能量 | W |  |  | 5 | μJ |  | 3 |
| 误差放大器输出吸电流 | Io |  |  | 10 | mA |  | 3 |
| 电流传感和电压反馈输入 | Vin | -0.3 |  | 5.5 | V |  | 3 |
| 工作结温 | Tj |  |  | 150 | ℃ |  | 3 |
| 贮存温度 | Tstg | -55 |  | 150 | ℃ |  | 3 |
| 引脚焊接温度 | TL |  |  | 260 | ℃ | 10s | 3 |
| 工作环境温度 | Tamb | 0 |  | 70 | ℃ |  | 3 |
| 基准输出电压 | Vref | 4.9 | 5 | 5.1 | V | Tj=25℃ Io=1mA | 3 |
| 线性调整率 | ⊿Vref |  | 6 | 20 | mV | 12V≤Vi≤25V | 3 |
| 负载调整率 | ⊿Vref |  | 6 | 25 | mV | 1mA≤Vi≤20mA | 3 |
| 短路输出电流 | Isc | -30 | -100 | -180 | mA | Ta=25℃ | 3 |
| 振荡频率 | fosc | 47 | 52 | 57 | kHz | Tj=25℃ | 3 |
| 振荡电压特性 | ⊿fosc/V |  | 0.2 | 1 | % | Vcc=12V to 25V | 3 |
| 放电电流 | Idischg | 7.8 | 8.3 | 8.8 | mA | Tj=25℃ | 3 |
| 输入电压 | Vfb | 2.42 | 2.5 | 2.58 | V | Vpin1=2.5V | 3 |
| 输入偏置电流 | Ibias |  | -0.1 | -2 | μA | Vfb=5V | 3 |
| 开环电压增益 | Gvo1 | 65 | 90 |  | dB | 2V≤Vo≤4V | 3 |
| 单位增益带宽 | BW | 0.7 | 1 |  | MHz | Tj=25℃ | 3 |
| 电源纹波抑制比 | PSRR | 60 | 70 |  | dB | 12V≤Vi≤25V | 3 |
| 输出灌电流 | Isink | 2 | 12 |  | mA | Vpin2=2.7V,Vpin1=1.1V | 4 |
| 输出吸电流 | Isource | -0.5 | -1 |  | mA | Vpin2=2.3V,Vpin1=5V | 4 |
| 误差放大器输出高电平 | VOH | 5 | 6.2 |  | V | Vpin2=2.3V; Rl=15kΩ to Ground | 4 |
| 误差放大器输出低电平 | VOL | 0.8 | 1.1 |  | V | Vpin2=2.7V; Rl=15kΩ to Pin8 | 4 |
| 电流传感增益 | Gv | 2.85 | 3 | 3.15 | V/V |  | 4 |
| 最大输入信号 | V3 | 0.9 | 1 | 1.1 | V | Vpin1=5V | 4 |
| 电流传感电源抑制比 | SVR | 70 |  |  | dB | 12V≤Vi≤25V | 4 |
| 电流传感输入偏置电流 | Ib | -2 | -10 |  | μA |  | 4 |
| 传输延迟 电流传感输入到输出 | TPLH(in/off) |  | 150 | 300 | ns |  | 4 |
| 输出低电平 | VOL |  | 0.1 | 0.4 | V | Isink=20mA | 4 |
| 输出低电平 | VOL |  | 1.6 | 2.2 | V | Isink=200mA | 4 |
| 输出高电平 | VOH |  | 13 | 13.5 | V | Isource=20 mA | 4 |
| 输出高电平 | VOH |  | 12 | 13.5 | V | Isource=200 mA | 4 |
| 欠压锁定的输出电压 | Vols |  | 0.7 | 1.2 | V | Vcc=6V;Isink=1mA | 4 |
| 输出电压上升时间 | tr |  | 50 | 150 | ns | Tj=25℃ Cl=1nF | 4 |
| 输出电压下降时间 | tf |  | 50 | 150 | ns | Tj=25℃ Cl=1nF | 4 |
| 起动电压 | Vth | 14.5 | 16 | 17.5 | V |  | 4 |
| 维持电压 | Vcc(min) | 8.5 | 10 | 11.5 | V |  | 4 |
| 最大占空比 | D (max) | 94 | 96 | 100 | % |  | 4 |
| 最小占空比 | D (min) | 0 |  |  | % |  | 4 |
| 启动电流 | Ist |  | 0.12 | 0.3 | mA | Vi=14V | 4 |
| 工作电源电流 | Ii |  | 12 | 17 | mA | Vpin2=Vpin3=0V | 4 |
| Zener 电压 | Viz | 30 | 36 |  | V | Ii=25mA | 4 |

## CAD (KiCad official)

- Symbol: `UC3842M`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOP-8 (KiCad packages3D, STEP)
- 3D model files: `uc3842m-etched.step` / `uc3842m-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `uc3842m.step` / `uc3842m.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [HGSEMI datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8758163524801433600) (10 pp, sha256 `f01f4065a8e98ef1`, retrieved 2026-10-18, tier: lcsc)
- **Datasheet language:** Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
- **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](docs/uc3842m-datasheet.pdf)