# LM4991MAX

**Texas Instruments** · Audio Amplifiers · SOIC-8

LM4991MAX from Texas Instruments, in a SOIC-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 | SHUTDOWN | input | Shutdown control input that turns off the amplifier bias circuitry when VDD (logic high) is applied, giving about 0.1µA typical shutdown current; it should be tied to a definite voltage. |
| 2 | BYPASS | passive | Half-supply bypass pin for the bias voltage, where an external capacitor CB (1.0µF recommended) to ground improves PSRR and click-and-pop performance. |
| 3 | +IN | input | Non-inverting amplifier input. |
| 4 | -IN | input | Inverting amplifier input, where the input resistor Ri and feedback resistor Rf set the gain (AVD = 2*(Rf/Ri)). |
| 5 | Vo1 | output | Bridged amplifier output 1, driven by the first amplifier and biased at VDD/2 with no output coupling capacitor required. |
| 6 | VDD | power_in | Positive supply input, with an operating range of 2.2V to 5.5V (6.0V absolute maximum) that needs a nearby bypass capacitor. |
| 7 | GND | power_in | Ground connection. |
| 8 | Vo2 | output | Bridged amplifier output 2, driven by the second amplifier (unity-gain inverting), 180° out of phase with Vo1. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SOIC-8 |
| Category | Amplifiers/Comparators |
| Pins | 8 |

## CAD (KiCad official)

- Symbol: `LM4991MAX`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOIC-8 (KiCad packages3D, STEP)
- 3D model files: `lm4991max-etched.step` / `lm4991max-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lm4991max.step` / `lm4991max.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/lm4991) (27 pp, sha256 `69de3029d691cac1`, retrieved 2026-10-07, 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/lm4991max-datasheet.pdf)