# UC3845N

**Texas Instruments** · AC-DC Controllers And Regulators · DIP-8

UC3845N from Texas Instruments, in a DIP-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 compensation pin; external compensation network connects here to shape the error amplifier output, and the amplifier has internal current limiting so COMP can be forced to GROUND externally to set zero duty cycle. |
| 2 | VFB | input | Inverting input of the internal error amplifier, used to close the voltage feedback loop, with the datasheet noting that VFB lead length and stray capacitance should be kept minimal for stability. |
| 3 | ISENSE | input | Primary-side current sense input connected to the MOSFET current sense resistor and to the PWM comparator, which terminates OUTPUT conduction; the datasheet gives a typical 1 V peak input and recommends an RC filter against leading-edge spikes. |
| 4 | RT/CT | bidirectional | Oscillator timing pin, with timing resistor RT connected from VREF and timing capacitor CT to GROUND setting the switching frequency; the datasheet states the timing resistor must never be less than 5 kΩ. |
| 5 | GROUND | power_in | Analog and power ground return for this 8-pin package (no separate PWRGND pin), which the datasheet recommends keeping separate from high-current gate driver return paths. |
| 6 | OUTPUT | output | Totem-pole gate driver for the external MOSFET, sourcing and sinking peak currents up to 1 A, and held low while VCC is below the turn-on threshold. |
| 7 | VCC | power_in | Power supply input for the analog controller and gate driver current; the datasheet recommends 12 V to 28 V operation, with an absolute maximum of 30 V from a low-impedance source, and a bypass capacitor of typically 0.1 µF to GROUND placed close to the pin. |
| 8 | VREF | power_in | 5 V reference output that must be bypassed to GROUND with at least 0.1 µF ceramic capacitor placed close to the pin, with an additional bypass needed for any external load, and the datasheet gives a reference output short-circuit current of -30 to -100 mA. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | DIP-8 |
| Category | Power Management (PMIC) |
| Pins | 8 |

## CAD (KiCad official)

- Symbol: `UC3845N`
- Footprint: `Package_DIP:DIP-8_W7.62mm`
- 3D model: DIP-8 (KiCad packages3D, STEP)
- 3D model files: `uc3845n-etched.step` / `uc3845n-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `uc3845n.step` / `uc3845n.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/cn/lit/gpn/uc2845) (61 pp, sha256 `0f875fd24cbb5fda`, retrieved 2026-10-10, 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/uc3845n-datasheet.pdf)