# LM51581QRTERQ1

**Texas Instruments** · DC-DC Converters · WQFN-16(3x3)

LM51581QRTERQ1 from Texas Instruments, in a WQFN-16(3x3). 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 | PGND | power_in | Power ground pin; source connection of the internal N-channel power MOSFET. |
| 2 | VCC | power_out | Output of the internal VCC regulator and supply voltage input of the internal MOSFET driver; connect 1-µF ceramic bypass capacitor from this pin to PGND. |
| 3 | BIAS | power_in | Supply voltage input to the VCC regulator; operating range 3.2V to 60V absolute maximum 65V; connect bypass capacitor from this pin to PGND. |
| 4 | PGOOD | tri_state | Power-good indicator; open-drain output which goes low if FB is below the undervoltage threshold (VUVTH); connect pullup resistor to system voltage rail. |
| 5 | RT | input | Switching frequency setting pin; switching frequency is programmed by a single resistor between RT and AGND in the range 100 kHz to 2.2 MHz. |
| 6 | EN/UVLO/SYNC | input | Enable/UVLO/synchronization pin; enables converter (>VEN threshold), programs undervoltage lockout via resistive voltage divider, and accepts external negative pulse for clock synchronization. |
| 7 | AGND | power_in | Analog ground pin; connect to the analog ground plane through a wide and short path. |
| 8 | COMP | output | Output of the internal transconductance error amplifier; connect loop compensation components between this pin and AGND. |
| 9 | FB | input | Inverting input of the error amplifier; connect voltage divider to set output voltage in boost, SEPIC, or primary-side regulated flyback topologies; input range 0V to 4.0V. |
| 10 | SS | input | Soft-start time programming pin; external capacitor and internal current source set the ramp rate of the internal error amplifier reference during soft start. |
| 11 | MODE | input | Mode configuration pin; setting controls hiccup mode protection and spread spectrum features via voltage level (0V, 370mV, 620mV, or >1V) or resistor to AGND. |
| 12 | NC | unconnected | No internal electrical contact. |
| 13 | SW | output | Switch pin; drain connection of the internal N-channel power MOSFET; 85V absolute maximum rating, 5-ns transient minimum -6V. |
| 14 | SW | output | Switch pin; drain connection of the internal N-channel power MOSFET; 85V absolute maximum rating, 5-ns transient minimum -6V. |
| 15 | NC | unconnected | No internal electrical contact. |
| 16 | PGND | power_in | Power ground pin; source connection of the internal N-channel power MOSFET. |
| 17 | EP | passive | Exposed pad (from the footprint; not named in the datasheet pin table). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | WQFN-16(3x3) |
| Category | Power Management (PMIC) |
| Pins | 17 |

## CAD (KiCad official)

- Symbol: `LM51581QRTERQ1`
- Footprint: `Package_DFN_QFN:QFN-16-1EP_3x3mm_P0.5mm_EP1.7x1.7mm`
- 3D model: WQFN-16(3x3) (KiCad packages3D, STEP)
- 3D model files: `lm51581qrterq1-etched.step` / `lm51581qrterq1-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lm51581qrterq1.step` / `lm51581qrterq1.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/lm5158-q1) (45 pp, sha256 `c10929600ea42a9c`, retrieved 2026-10-03, 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-4-5-20251001` (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/lm51581qrterq1-datasheet.pdf)