ISO7221
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TI dual-channel digital isolator, SOIC-8. Galvanic isolation, one channel each direction, up to 150 Mbps. Datasheet-verified.
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markdownISO7221
Texas Instruments · 2-channel digital isolator · SOIC-8
A dual-channel digital isolator in SOIC-8 that passes logic signals across a galvanic isolation barrier, a fast, reliable replacement for optocouplers. It carries two channels in opposite directions (one A-to-B, one B-to-A), each side powered from its own supply (VCC1, VCC2), with an isolation barrier rated to about 2.5 kVrms that breaks ground loops and protects low-voltage logic from a high-voltage or noisy domain. Built on a capacitive isolation core, it is faster (up to 150 Mbps depending on grade), lower power, and more stable over temperature and lifetime than an optocoupler. Common uses are isolated UART/SPI links, RS-485/CAN side isolation, and isolated control signals. The related ISO7220/7231/7241 offer other channel counts and directions.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VCC1 | power_in | Power supply for side 1 (input for channel A, output for channel B). 2.8 V / 3.3 V / 5 V; independently referenced to GND1. Decouple locally with a 0.1 µF ceramic near the pin. |
| 2 | OUTA | output | Buffered CMOS output of channel A on side 1 of the isolation barrier (isolated copy of INA on side 2). 4 mA drive; output high/low tracks VCC1. |
| 3 | INB | input | Digital input of channel B on side 1. A-, B-, and C-option devices apply a TTL input threshold (VIH ≥ 2 V, VIL ≤ 0.8 V) with input noise filtering; M-option uses a CMOS threshold (0.7·VCC / 0.3·VCC). If undriven for >4 µs the failsafe drives the isolated output high. |
| 4 | GND1 | power_in | Ground reference for side 1 (VCC1 domain). Galvanically isolated from GND2 by the SiO₂ barrier. |
| 5 | GND2 | power_in | Ground reference for side 2 (VCC2 domain). Galvanically isolated from GND1 by the SiO₂ barrier. |
| 6 | OUTB | output | Buffered CMOS output of channel B on side 2 (isolated copy of INB on side 1). 4 mA drive; output high/low tracks VCC2. |
| 7 | INA | input | Digital input of channel A on side 2. A-, B-, and C-option devices use TTL thresholds with input noise filtering; M-option uses CMOS thresholds. Failsafe forces the isolated output high when INA is undriven for >4 µs. |
| 8 | VCC2 | power_in | Power supply for side 2 (input for channel A, output for channel B). 2.8 V / 3.3 V / 5 V; independently referenced to GND2. Decouple locally with a 0.1 µF ceramic near the pin. |
Key specifications
| Parameter | Value |
|---|---|
| Type | 2-channel digital isolator |
| Channels | 2 (one each direction) |
| Isolation | ~2.5 kVrms barrier (capacitive) |
| Data rate | up to 150 Mbps (by grade) |
| Supplies | VCC1 + VCC2 (independent) |
| Advantage | faster + longer-life than optocoupler |
| Supply voltage | 3.3-5 V each side |
| Package | SOIC-8 |
Ordering variants
Same part, different packaging or reel option.
ISO7221CD (SOIC-8)ISO7221AD (SOIC-8)
CAD (KiCad official)
- Symbol:
ISO7221 (generated from datasheet; KiCad has no symbol) - Footprint:
Package_SO:SOIC-8_3.9x4.9mm_P1.27mm - 3D model: SOIC-8 (KiCad packages3D)
- 3D model files:
iso7221-etched.step/iso7221-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);iso7221.step/iso7221.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: Texas Instruments datasheet (39 pp, sha256
b74a541cca2d68e0, retrieved 2026-08-17, tier: manufacturer) - 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).