# TMI3281

**TMI** · DC-DC Converters · SOT-23-6

TMI3281 from TMI, in a SOT-23-6. 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 | BS | passive | Bootstrap pin: a capacitor connected between LX and BS is required to form the floating supply for the high-side switch driver (BS absolute voltage range -0.6 V to 25 V). |
| 2 | GND | power_in | Ground pin; the datasheet recommends connecting GND to a large copper area to cool the chip and improve thermal performance. |
| 3 | FB | input | Voltage feedback input; connect to the center point of the external resistor divider, with a regulated feedback voltage of 0.588 V to 0.612 V (0.6 V typical) at 25 °C and FB absolute maximum of 6 V. |
| 4 | EN | input | Enable pin: drive to logic-high to enable the IC and to logic-low to enter micro-power shutdown; do not leave floating (EN rising threshold 1.1 to 1.5 V, falling threshold 0.9 to 1.3 V, absolute maximum -0.3 V to 23 V). |
| 5 | IN | power_in | Power supply pin; recommended input voltage range is 3.5 V to 18 V, with UVLO threshold of 3.0 V and OVP threshold of 19 V. |
| 6 | LX | output | Switching pin connected to the internal power MOSFETs and the output inductor; LX voltage absolute range is -0.3 V to 23 V (-4.0 V to 23 V for transients under 10 ns). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | TMI |
| Package | SOT-23-6 |
| Category | Power Management (PMIC) |
| Pins | 6 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Input Supply Voltage, EN |  | -0.3 |  | 23 | V |  | 2 |
| LX Voltages |  | -0.3 |  | 23 | V |  | 2 |
| LX Voltages (<10ns transient) |  | -4 |  | 23 | V | <10ns transient | 2 |
| FB Voltage |  | -0.3 |  | 6 | V |  | 2 |
| BS Voltage |  | -0.6 |  | 25 | V |  | 2 |
| Storage Temperature Range |  | -65 |  | 150 | °C |  | 2 |
| Junction Temperature |  |  |  | 160 | °C | Note 2 | 2 |
| Power Dissipation |  |  |  | 1000 | mW |  | 2 |
| Lead Temperature (Soldering,10s) |  |  |  | 260 | °C | Soldering, 10s | 2 |
| Voltage Range IN |  | 3.5 |  | 18 | V |  | 3 |
| TJ Operating Junction Temperature | TJ | -40 |  | 125 | °C |  | 3 |
| Input Voltage Range |  | 3.5 |  | 18 | V |  | 4 |
| Regulated Feedback Voltage | VFB | 0.588 | 0.6 | 0.612 | V | TA = 25°C, 3.5V≤VIN ≤18V | 4 |
| EN Rising Threshold |  | 1.1 | 1.3 | 1.5 | V |  | 4 |
| EN Falling Threshold |  | 0.9 | 1.1 | 1.3 | V |  | 4 |
| Soft Start time |  | 0.7 | 1 | 1.3 | ms |  | 4 |
| Junction-to-ambient thermal resistance | θJA |  | 130 | 130 | °C/W | JESD51-7, 4-layer PCB (Note 3) | 3 |
| Junction-to-case(top) thermal resistance | θJC |  | 60 | 60 | °C/W |  | 3 |

## CAD (KiCad official)

- Symbol: `TMI3281`
- Footprint: `Package_TO_SOT_SMD:SOT-23-6`
- 3D model: SOT-23-6 (KiCad packages3D, STEP)
- 3D model files: `tmi3281-etched.step` / `tmi3281-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `tmi3281.step` / `tmi3281.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [TMI datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8588906510902562817) (12 pp, sha256 `fb159aa0e83248e1`, retrieved 2026-10-09, 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/tmi3281-datasheet.pdf)