# ADS8638SRGET

**Texas Instruments** · Analog To Digital Converters (ADCs) · VQFN-24-EP(4x4)

ADS8638SRGET from Texas Instruments, in a VQFN-24-EP(4x4). 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 | AVDD | power_in | Analog power supply for the device. |
| 2 | AGND | power_in | Analog ground. |
| 3 | AGND | power_in | Analog ground. |
| 4 | NC | unconnected | This pin is not internally connected and should not be left floating; it is recommended to connect it to AGND. |
| 5 | AINGND | power_in | Common for all analog input channels; acts as the ground sense terminal. |
| 6 | AIN7 | input | Analog input channel 7. |
| 7 | AIN6 | input | Analog input channel 6. |
| 8 | AIN5 | input | Analog input channel 5. |
| 9 | AIN4 | input | Analog input channel 4. |
| 10 | AIN3 | input | Analog input channel 3. |
| 11 | AIN2 | input | Analog input channel 2. |
| 12 | AIN1 | input | Analog input channel 1. |
| 13 | AIN0 | input | Analog input channel 0. |
| 14 | HVDD | power_in | High-voltage positive supply for the multiplexer channels. |
| 15 | HVSS | power_in | High-voltage negative supply for the multiplexer channels. |
| 16 | CS | input | SPI chip select digital input. |
| 17 | SCLK | input | SPI serial clock digital input. |
| 18 | DIN | input | SPI serial data digital input. |
| 19 | DOUT | output | SPI serial data digital output. |
| 20 | DGND | power_in | Digital ground. |
| 21 | DVDD | power_in | Digital I/O supply; may operate from 5 V down to 1.8 V. |
| 22 | AL_PD | bidirectional | User-configurable pin: active-high alarm output when programmed as AL, or active-low asynchronous power-down input when programmed as PD (default is PD input). |
| 23 | REFGND | power_in | Reference ground input when an external reference is selected; acts as reference decoupling ground when the internal reference is selected. |
| 24 | REF | input | Reference input when an external reference is selected; acts as reference decoupling terminal when the internal reference is selected. |
| 25 | EP | passive | Exposed pad (from the footprint; not named in the datasheet pin table). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | VQFN-24-EP(4x4) |
| Category | ADC/DAC/Data Conversion |
| Pins | 25 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| AVDD to AGND, DVDD to DGND |  | -0.3 |  | 7 | V |  | 2 |
| HVDD to AGND |  | -0.3 |  | 18 | V |  | 2 |
| HVSS to AGND |  | -18 |  | 0.3 | V |  | 2 |
| HVDD to HVSS |  | -0.3 |  | 33 | V |  | 2 |
| Operating temperature range |  | -40 |  | 125 | °C |  | 2 |
| Storage temperature range |  | -65 |  | 150 | °C |  | 2 |
| ESD HBM, all pins |  | -2000 |  | 2000 | V | Human body model | 2 |
| ESD CDM, all pins |  | -500 |  | 500 | V | Charged device model | 2 |
| AVDD supply voltage | VAVDD | 2.7 | 3.3 | 5.25 | V |  | 5 |
| DVDD supply voltage | VDVDD | 1.65 | 3.3 | 5.25 | V |  | 5 |
| HVDD supply voltage | VHVDD | 5 | 10 | 15 | V | 10V < VHVDD, VHVSS < 30V | 5 |
| HVSS supply voltage | VHVSS | -15 | -10 | 0 | V | 10V < VHVDD, VHVSS < 30V | 5 |
| Specified temperature range |  | -40 |  | 125 | °C | Specified performance | 5 |
| AINGND absolute input range |  | -0.2 |  | 0.2 | V |  | 3 |
| Input capacitance |  |  | 8 |  | pF |  | 3 |
| Input leakage current |  |  |  | 200 | nA | At +125°C | 3 |
| Resolution |  |  | 12 |  | Bits |  | 3 |
| No missing codes |  | 12 |  |  | Bits |  | 3 |
| Integral linearity | INL | -1.5 | 0.9 | 1.5 | LSB | typ printed +0.9/-0.9 | 3 |
| Differential linearity | DNL | -1 | 0.9 | 1.6 | LSB | typ printed +0.9/-0.5 | 3 |
| Offset error |  | -3 | 0.8 | 3 | LSB | typ printed ±0.8 | 3 |
| Offset error drift |  |  | 0.75 |  | ppmFS/°C |  | 3 |
| Gain error |  | -8 | 2 | 8 | LSB | typ printed ±2; does not include reference drift | 3 |
| Gain error drift |  |  | 1.2 |  | ppm/°C |  | 3 |
| Noise |  |  | 0.33 |  | LSB | At FFCh output code | 3 |
| Power-supply rejection |  |  | -87 |  | dB | 250mVPP and 480Hz ripple on AVDD | 3 |
| Isolation crosstalk |  |  | -110 |  | dB | Channel 0 permanently selected, 2kHz full-scale sine wave on channel 1, all other channels grounded | 3 |
| Memory crosstalk |  |  | -81 |  | dB | Channel 0, 2kHz full-scale sine wave on channel 1, device scans channel 0 and channel 1 alternately | 3 |
| Conversion time |  |  | 750 |  | ns | At 20MHz SCLK, DVDD = 2.7V to 5.25V | 3 |
| Acquisition time |  |  | 250 |  | ns | AVDD = 2.7V to 5.25V | 3 |
| Maximum throughput rate |  | 1 |  |  | MSPS | At 20MHz SCLK, DVDD = 2.7V to 5.25V | 3 |
| Aperture delay |  |  | 13 |  | ns |  | 3 |
| Step response |  |  | 250 |  | ns |  | 3 |
| Total harmonic distortion | THD |  | -81 |  | dB | At 1kHz | 4 |
| Total harmonic distortion | THD |  | -80 |  | dB | At 100kHz | 4 |
| Signal-to-noise ratio | SNR | 71 | 71.8 |  | dB | At 1kHz | 4 |
| Signal-to-noise and distortion ratio | SINAD | 70.1 | 71.3 |  | dB | At 1kHz | 4 |
| Spurious-free dynamic range | SFDR |  | -83 |  | dB | At 1kHz | 4 |
| Full-power bandwidth |  |  | 1 |  | MHz | At -3dB | 4 |
| Logic input high | VIH | 0.7 |  |  | DVDD |  | 4 |
| Logic input low | VIL |  |  | 0.3 | DVDD |  | 4 |
| Logic output high | VOH | 0.8 |  |  | DVDD | With 20pF load on SDO | 4 |
| Logic output low | VOL |  |  | 0.2 | DVDD | With 20pF load on SDO | 4 |
| External reference input voltage range | VREF | 2 |  | 3 | V | Max is 3.0 or AVDD, whichever is less | 4 |
| Internal reference output voltage |  |  | 2.5 |  | V |  | 4 |
| Internal reference initial accuracy |  | -1.2 |  | 1.2 | % |  | 4 |
| Internal reference temperature drift |  |  | 20 |  | ppm/°C |  | 4 |
| Reference drive current, source |  |  | 750 |  | µA | Short-circuit protected | 4 |
| Reference drive current, sink |  |  | 20 |  | µA |  | 4 |
| Reference turn-on settling time |  |  | 9 |  | ms | With 10µF decoupling capacitor from REF to REFGND | 4 |
| Temperature sensor absolute accuracy |  |  | 5 |  | % of FSR |  | 4 |
| AVDD dynamic current | IAVDD(dynamic) |  | 3.1 | 3.6 | mA | VAVDD = 4.75V to 5.25V, 1MHz throughput, normal mode, internal reference and temperature sensor off | 5 |
| AVDD static current | IAVDD(static) |  | 1.5 | 1.9 | mA | VAVDD = 4.75V to 5.25V, SCLK off, normal mode, internal reference and temperature sensor off | 5 |
| Additional AVDD current, internal reference on | IAVDD(ref) |  | 180 |  | µA | VAVDD = 2.7V to 5.25V, temperature sensor off | 5 |
| Additional AVDD current, temperature sensor on | IAVDD(temp) |  | 400 |  | µA | VAVDD = 2.7V to 5.25V, internal reference off | 5 |
| HVDD dynamic current | IHVDD(dynamic) |  | 270 | 350 | µA | HVDD = 15V and 1MSPS throughput | 5 |
| HVSS dynamic current | IHVSS(dynamic) |  |  | 520 | µA | HVSS = -15 V and 1MSPS throughput | 5 |
| DVDD supply current | IDVDD |  | 2.5 |  | mA | DVDD = 3.3V, fSAMPLE = 1MSPS, DOUT load = 20pF | 5 |
| Junction-to-ambient thermal resistance | θJA |  | 32.6 |  | °C/W | RGE, 24 pins | 5 |
| Junction-to-case (top) thermal resistance | θJCtop |  | 30.5 |  | °C/W | RGE, 24 pins | 5 |
| Junction-to-board thermal resistance | θJB |  | 3.3 |  | °C/W | RGE, 24 pins | 5 |
| Junction-to-case (bottom) thermal resistance | θJCbot |  | 2.6 |  | °C/W | RGE, 24 pins | 5 |
| Delay time, CS high to DOUT high-z | td(CS-DOHZ) | 6.4 |  | 22 | ns | DVDD = 3V | 6 |
| Delay time, CS low to first data out | td(CS-DO) |  |  | 40 | ns | DVDD = 3V | 6 |
| Delay time, SCLK falling to DOUT | td(SCLK-DOUT) |  |  | 33 | ns | DVDD = 3V | 6 |

## CAD (KiCad official)

- Symbol: `ADS8638SRGET`
- Footprint: `Package_DFN_QFN:QFN-24-1EP_4x4mm_P0.5mm_EP2.6x2.6mm`
- 3D model: VQFN-24-EP(4x4) (KiCad packages3D, STEP)
- 3D model files: `ads8638srget-etched.step` / `ads8638srget-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ads8638srget.step` / `ads8638srget.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/lit/ds/symlink/ads8638srget.pdf) (75 pp, sha256 `08d5acce7caa1cda`, retrieved 2026-10-31, tier: manufacturer)
- **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/ads8638srget-datasheet.pdf)