# AT24C128MM

**HGSEMI** · EEPROM · MSOP-8

AT24C128MM from HGSEMI, in a MSOP-8. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | E0 | input | Slave address input bit 0. Combined with E1/E2 to select one of up to 8 devices on the same I2C bus. Internally pulled down to Vss if left floating. |
| 2 | E1 | input | Slave address input bit 1. Hardware-selectable device address bit; internally pulled down to Vss if left floating. |
| 3 | E2 | input | Slave address input bit 2. Hardware-selectable device address bit; internally pulled down to Vss if left floating. |
| 4 | Vss | power_in | Ground reference for the Vcc supply. |
| 5 | SDA | bidirectional | I2C serial data (bidirectional, open-drain). Requires an external pull-up resistor to Vcc. Input capacitance approx. 8 pF. |
| 6 | SCL | input | I2C serial clock input. Positive-edge clocks data in, negative-edge clocks data out. Supports up to 400 kHz (1.7V) or 1 MHz (higher Vcc). |
| 7 | WCB | input | Write Control input, active low. Tie to Vss to allow write operations; tie to Vcc to inhibit all writes to the memory array. Internally pulled down to Vss if left floating. |
| 8 | VCC | power_in | Supply voltage input, 1.7V to 5.5V. Typical read current 0.2 mA and write current 0.8 mA at 400 kHz. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | HGSEMI |
| Package | MSOP-8 |
| Category | Memory |
| Pins | 8 |

## Ordering variants

- `AT24C128MM/TR`
- `AT24C128MMN`
- `AT24C128MMM/TR`
- `AT24C128MMMT/TR`
- `AT24C128MMDQ2/TR`
- `AT24C128MMDQ3/TR`
- `AT24C128MMM5/TR`

## CAD (KiCad official)

- Symbol: `AT24C128MM`
- Footprint: `Package_SO:MSOP-8_3x3mm_P0.65mm`
- 3D model: MSOP-8 (KiCad packages3D, STEP)
- 3D model files: `at24c128mm-etched.step` / `at24c128mm-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `at24c128mm.step` / `at24c128mm.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [HGSEMI datasheet](docs/at24c128mm-datasheet.pdf) (19 pp, sha256 `ade6fc1683c10678`, retrieved 2026-08-17, tier: lcsc)
- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/at24c128mm-datasheet.pdf)