# UCC3946PWTR

**Texas Instruments** · Monitors & Reset Circuits · TSSOP-8

UCC3946PWTR from Texas Instruments, in a TSSOP-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 | GND | power_in | Ground reference for the device. |
| 2 | RTH | input | Reset threshold input compared to an internal 1.235 V reference (the pin table says 1.25 V); external resistors R1 and R2 program the reset threshold. |
| 3 | RES | output | Active-low reset output that goes high only after RTH has risen above 1.235 V and the reset period has elapsed, and is ensured low for VDD down to 1 V. |
| 4 | RP | input | Reset period programming pin; an external capacitor sets the period (TRP = 3.125 x CRP, with TRP in ms and CRP in nF) and is charged by a 400 nA source. |
| 5 | WDO | output | Active-low watchdog output that is asserted low if WDI is not toggled within the watchdog period. |
| 6 | WP | input | Watchdog period programming pin; an external capacitor sets the period (TWP = 25 x CWP, with TWP in ms and CWP in nF). |
| 7 | WDI | input | Watchdog timer input that must be toggled within the watchdog period to prevent WDO from being asserted, with VIH = 0.7 x VDD and VIL = 0.3 x VDD. |
| 8 | VDD | power_in | Supply voltage for the device, 2.0 V to 5.5 V for the UCC3946, with a 0.1 uF decoupling capacitor to GND recommended. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | TSSOP-8 |
| Category | Power Supply Chip |
| Pins | 8 |

## CAD (KiCad official)

- Symbol: `UCC3946PWTR`
- Footprint: `Package_SO:TSSOP-8_3x3mm_P0.65mm`
- 3D model: TSSOP-8 (KiCad packages3D, STEP)
- 3D model files: `ucc3946pwtr-etched.step` / `ucc3946pwtr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ucc3946pwtr.step` / `ucc3946pwtr.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/ucc3946) (20 pp, sha256 `6dea29f2ee7ad735`, retrieved 2026-10-11, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-5-5` (text+vision), consensus `claude-opus-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/ucc3946pwtr-datasheet.pdf)