# UC2843B

**UMW** · DC-DC Converters · SOP-8

UC2843B from UMW, 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. |
| 2 | VFB | input | This is the inverting input of the Error Amplifier, normally connected to the switching power supply output through a resistor divider. |
| 3 | ISENSE | input | A voltage proportional to inductor current is connected to this input, and the PWM uses it to terminate output switch conduction. |
| 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 | GND | 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 1A. |
| 7 | VCC | power_in | This pin is the positive supply of the integrated circuit. |
| 8 | Vref | power_out | This is the reference output, which provides charging current for capacitor CT through resistor RT. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | UMW |
| 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 |
|---|---|---|---|---|---|---|---|
| Supply Voltage (low impedance source) | VCC |  |  | 30 | V |  | 3 |
| Output Current | IO | -1 |  | 1 | A |  | 3 |
| Input Voltage (Analog Inputs pins 2,3) | VI | -0.3 |  | 5.5 | V |  | 3 |
| Error Amp Output Sink Current | ISINK (E.A) |  |  | 10 | mA |  | 3 |
| Power Dissipation | PD |  |  | 1 | W | TA=25°C | 3 |
| Storage Temperature Range | TSTG | -65 |  | 150 | °C |  | 3 |
| Lead Temperature (soldering 5 sec.) | TL |  |  | 260 | °C | soldering 5 sec. | 3 |
| Operating Ambient Temperature | TA | -25 |  | 85 | °C |  | 3 |
| Reference Output Voltage | VREF | 4.95 |  | 5.05 | V | TJ=25°C, IREF=1mA | 4 |
| Error Amplifier Input Voltage | VI(E.A) | 2.42 | 2.5 | 2.58 | V |  | 4 |
| Gain | GV | 2.85 | 3 | 3.15 | V/V |  | 4 |
| Maximum input signal | VI(MAX) | 0.9 | 1 | 1.1 | V |  | 4 |
| Maximum Duty Cycle (2842/43) | D(MAX) | 95 | 97 | 100 | % |  | 5 |
| Start Threshold (2843/45) | VTH(ST) | 7.8 | 8.4 | 9 | V |  | 5 |
| Min. Operating Voltage after turn-on (2843/45) | VOPR(min) | 7 | 7.6 | 8.2 | V |  | 5 |

## CAD (KiCad official)

- Symbol: `UC2843B`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOP-8 (KiCad packages3D, STEP)
- 3D model files: `uc2843b-etched.step` / `uc2843b-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `uc2843b.step` / `uc2843b.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [UMW datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8757272555222769664) (13 pp, sha256 `d748ab15bdd235a3`, 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](docs/uc2843b-datasheet.pdf)