# DS8921AMX

**Texas Instruments** · RS-485/RS-422 ICs · SOIC-8

DS8921AMX 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 | VCC | power_in | Power supply pin for the 5-V supply (4.5 V to 5.5 V recommended), to be bypassed with a 0.1-µF capacitor placed close to the pin. |
| 2 | RO | output | Receiver output, TTL-compatible single-ended output of the differential receiver. |
| 3 | DI | input | TTL/CMOS-compatible driver input. |
| 4 | GND | power_in | Power ground pin. |
| 5 | DO- | output | Complementary differential driver output (DO-) that drives the twisted-pair or parallel-wire transmission line. |
| 6 | DO+ | output | Differential driver output (DO+) that drives the transmission line and follows DI per the function table. |
| 7 | RI- | input | Differential receiver input (RI-) with ±200 mV sensitivity over a ±7 V common-mode range. |
| 8 | RI+ | input | Differential receiver input (RI+) with ±200 mV sensitivity over a ±7 V common-mode range. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SOIC-8 |
| Category | Communication Interface Chip/UART/485/232 |
| Pins | 8 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Supply Voltage | VCC | 4.5 |  | 5.5 | V |  | 4 |
| Operating Temperature DS8921/DS8921A | TA | 0 |  | 70 | °C |  | 4 |
| Receiver Threshold Voltage | VTH | -200 | 35 | 200 | mV | -7 V ≤ VCM ≤ +7 V (typ printed as ±35) | 4 |
| Receiver Hysteresis | VHYST | 15 | 70 |  | mV | -7 V ≤ VCM ≤ +7 V | 4 |
| Receiver Input Resistance | RIN | 4 | 6 |  | kΩ | VIN = -7 V, +7 V, (Other Input = GND) | 4 |
| Receiver Input Current | IIN |  |  | 3.25 | mA | VIN = 10 V | 4 |
| Receiver Input Current | IIN | -3.25 |  |  | mA | VIN = -10 V | 4 |
| Receiver Output High Voltage | VOH | 2.5 |  |  | V | IOH = -400 μA | 4 |
| Receiver Output Low Voltage | VOL |  |  | 0.5 | V | IOL = 8 mA | 4 |
| Receiver Short-Circuit Current | ISC | -15 |  | -100 | mA | VCC = MAX, VOUT = 0 V | 4 |
| Driver Input High Voltage | VIH | 2 |  |  | V |  | 4 |
| Driver Input Low Voltage | VIL |  |  | 0.8 | V |  | 4 |
| Driver Input Low Current | IIL | -40 |  | -200 | μA | VCC = MAX, VIN = 0.4 V | 4 |
| Driver Input High Current | IIH |  |  | 20 | μA | VCC = MAX, VIN = 2.7 V | 4 |
| Driver Input Current | II |  |  | 100 | μA | VCC = MAX, VIN = 7.0 V | 4 |
| Driver Input Clamp Voltage | VCL |  |  | -1.5 | V | VCC = MIN, IIN = -18 mA | 4 |
| Driver Output High Voltage | VOH | 2.5 |  |  | V | VCC = MIN, IOH = -20 mA | 4 |
| Driver Output Low Voltage | VOL |  |  | 0.5 | V | VCC = MIN, IOL = +20 mA | 4 |
| Driver Output Off Current | IOFF |  |  | 100 | μA | VCC = 0V, VOUT = 5.5 V | 4 |
| Driver Output Voltage Difference | /VT/, /VT/ |  |  | 0.4 | V |  | 4 |
| Driver Differential Output Voltage | VT | 2 |  |  | V |  | 4 |
| Driver Offset Voltage Difference | /VOS, VOS/ |  |  | 0.4 | V |  | 4 |
| Driver Short-Circuit Current | ISC | -30 |  | -150 | mA | VCC = MAX, VOUT = 0 V | 4 |
| Supply Current | ICC |  |  | 35 | mA | VCC = MAX, VOUT = Logic 0 | 4 |
| Receiver Propagation Delay tpLH | tpLH |  | 14 | 20 | ns | CL = 30 pF | 5 |
| Receiver Propagation Delay tpHL | tpHL |  | 14 | 20 | ns | CL = 30 pF | 5 |
| Receiver /tpLH-tpHL/ | /tpLH-tpHL/ |  | 0.5 | 3.5 | ns | CL = 30 pF | 5 |
| Driver Single-Ended tpLH | tpLH |  | 10 | 15 | ns | CL = 30 pF | 5 |
| Driver Single-Ended tpHL | tpHL |  | 10 | 15 | ns | CL = 30 pF | 5 |
| Driver Transition Time tTLH | tTLH |  | 5 | 8 | ns | CL = 30 pF | 5 |
| Driver Transition Time tTHL | tTHL |  | 5 | 8 | ns | CL = 30 pF | 5 |
| Driver Output Skew | Skew |  | 1 | 3.5 | ns | CL = 30 pF | 5 |
| Driver Differential tpLH | tpLH |  | 10 | 15 | ns | CL = 30 pF | 5 |
| Driver Differential tpHL | tpHL |  | 10 | 15 | ns | CL = 30 pF | 5 |
| Driver Differential /tpLH-tpHL/ | /tpLH-tpHL/ |  | 0.5 | 2.75 | ns | CL = 30 pF | 5 |
| Supply Voltage |  |  |  | 7 | V |  | 3 |
| Driver Input Voltage |  | -0.5 |  | 7 | V |  | 3 |
| Output Voltage |  |  |  | 5.5 | V |  | 3 |
| Receiver Output Sink Current |  |  |  | 50 | mA |  | 3 |
| Receiver Input Voltage |  | -10 |  | 10 | V |  | 3 |
| Differential Input Voltage |  | -12 |  | 12 | V |  | 3 |
| Maximum Package Power Dissipation, D Package |  |  |  | 730 | mW | at 25°C | 3 |
| Derating, D Package |  |  |  | 9.3 | mW/°C | above 25°C | 3 |
| Lead Temperature |  |  |  | 260 | °C | Soldering, 4 sec. | 3 |
| Maximum Junction Temperature |  |  |  | 150 | °C |  | 3 |
| Storage Temperature | Tstg | -65 |  | 165 | °C |  | 3 |
| ESD HBM | V(ESD) | -2000 |  | 2000 | V | Human-body model, ANSI/ESDA/JEDEC JS-001 | 4 |
| ESD CDM | V(ESD) | -1500 |  | 1500 | V | Charged-device model, JEDEC JESD22-C101 | 4 |

## CAD (KiCad official)

- Symbol: `DS8921AMX`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOIC-8 (KiCad packages3D, STEP)
- 3D model files: `ds8921amx-etched.step` / `ds8921amx-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ds8921amx.step` / `ds8921amx.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/ds8921amx.pdf) (22 pp, sha256 `0be14ebc915d205b`, retrieved 2026-10-27, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-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/ds8921amx-datasheet.pdf)