# AFE4400RHAT

**Texas Instruments** · Analog Front End (AFE) · VQFN-40-EP(6x6)

AFE4400RHAT from Texas Instruments, in a VQFN-40-EP(6x6). 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 | INN | input | Receiver input pin; connect to the photodiode anode. |
| 2 | INP | input | Receiver input pin; connect to the photodiode cathode. |
| 3 | RX_ANA_GND | power_in | Rx analog ground pin; connect to common board ground. |
| 4 | VCM | passive | Input common-mode voltage output; connect a series 1 kΩ resistor and a 10 nF decoupling capacitor to ground. |
| 5 | DNC | unconnected | Do not connect; leave as open circuit. |
| 6 | DNC | unconnected | Do not connect; leave as open circuit. |
| 7 | BG | passive | Decoupling capacitor for the internal band-gap voltage; connect a 2.2-µF capacitor to ground. |
| 8 | VSS | power_in | Substrate ground; connect to common board ground. |
| 9 | TX_REF | passive | Transmitter reference voltage, 0.75 V default after reset; connect a 2.2-µF decoupling capacitor to ground. |
| 10 | DNC | unconnected | Do not connect; leave as open circuit. |
| 11 | TX_CTRL_SUP | power_in | Transmit control supply pin with a 0.1-µF decoupling capacitor to ground; Tx supply range is 3.0 V to 5.25 V. |
| 12 | LED_DRV_GND | power_in | LED driver ground pin for the H-bridge; connect to common board ground. |
| 13 | LED_DRV_GND | power_in | LED driver ground pin for the H-bridge; connect to common board ground. |
| 14 | TXN | output | LED driver output B of the H-bridge; connect to the LED. |
| 15 | TXP | output | LED driver output B of the H-bridge; connect to the LED. |
| 16 | LED_DRV_GND | power_in | LED driver ground pin for the H-bridge; connect to common board ground. |
| 17 | LED_DRV_SUP | power_in | LED driver supply pin for the H-bridge; connect to an external supply capable of sourcing the large LED current drawn by this pin (Tx supply range 3.0 V to 5.25 V). |
| 18 | LED_DRV_SUP | power_in | LED driver supply pin for the H-bridge; connect to an external supply capable of sourcing the large LED current drawn by this pin (Tx supply range 3.0 V to 5.25 V). |
| 19 | RX_DIG_GND | power_in | Rx digital ground pin; connect to common board ground. |
| 20 | AFE_PDN | input | AFE-only power-down input, active low; can be connected to an MCU port pin. |
| 21 | DIAG_END | output | Output signal indicating completion of diagnostics; can be connected to an MCU port pin. |
| 22 | LED_ALM | output | Output signal indicating an LED cable fault; can be connected to an MCU port pin. |
| 23 | PD_ALM | output | Output signal indicating a PD sensor or cable fault; can be connected to an MCU port pin. |
| 24 | SCLK | input | SPI clock pin. |
| 25 | SPISOMI | output | SPI serial out, master in. |
| 26 | SPISIMO | input | SPI serial in, master out. |
| 27 | SPISTE | input | SPI serial interface enable. |
| 28 | ADC_RDY | output | Output signal indicating ADC conversion completion; can be connected to an external MCU interrupt input. |
| 29 | RESET | input | AFE-only reset input, active low; can be connected to an MCU port pin. |
| 30 | CLKOUT | output | Buffered 4-MHz clock output; can be connected to the clock input of an external MCU. |
| 31 | RX_DIG_SUP | power_in | Rx digital supply pin (Rx supply range 2.0 V to 3.6 V) with a 0.1-µF decoupling capacitor to ground. |
| 32 | RX_DIG_GND | power_in | Rx digital ground pin; connect to common board ground. |
| 33 | RX_ANA_SUP | power_in | Rx analog supply pin (Rx supply range 2.0 V to 3.6 V) with a 0.1-µF decoupling capacitor to ground. |
| 34 | DNC | unconnected | Do not connect; leave as open circuit. |
| 35 | DNC | unconnected | Do not connect; leave as open circuit. |
| 36 | RX_ANA_GND | power_in | Rx analog ground pin; connect to common board ground. |
| 37 | XOUT | passive | Crystal oscillator pin; connect an external 8-MHz crystal between XIN and XOUT with the vendor-specified load capacitors to ground. |
| 38 | XIN | passive | Crystal oscillator pin; connect an external 8-MHz crystal between XIN and XOUT with the vendor-specified load capacitors to ground. |
| 39 | RX_ANA_SUP | power_in | Rx analog supply pin (Rx supply range 2.0 V to 3.6 V) with a 0.1-µF decoupling capacitor to ground. |
| 40 | RX_ANA_GND | power_in | Rx analog ground pin; connect to common board ground. |
| 41 | EP | passive | Exposed pad (from the footprint; not named in the datasheet pin table). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | VQFN-40-EP(6x6) |
| Category | Data Acquisition |
| Pins | 41 |

## CAD (KiCad official)

- Symbol: `AFE4400RHAT`
- Footprint: `Package_DFN_QFN:QFN-40-1EP_6x6mm_P0.5mm_EP4.6x4.6mm`
- 3D model: VQFN-40-EP(6x6) (KiCad packages3D, STEP)
- 3D model files: `afe4400rhat-etched.step` / `afe4400rhat-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `afe4400rhat.step` / `afe4400rhat.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/afe4400) (87 pp, sha256 `32fd40f29bb554b6`, retrieved 2026-10-11, 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-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/afe4400rhat-datasheet.pdf)