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ISO7221

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TI dual-channel digital isolator, SOIC-8. Galvanic isolation, one channel each direction, up to 150 Mbps. Datasheet-verified.

componentinterfacedigital-isolatorgalvanic-isolationsoic-8texas-instruments
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docs iso7221: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray 1mo ago
viewers cross-highlight symbol + footprint viewers · Ray 2mo ago
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ISO7221.adom-lbr.json ISO7221: validated Fusion/EAGLE library + adom-lbr hub, generated from this page's KiCad sources · Ray 2mo ago
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ISO7221.lbr ISO7221: validated Fusion/EAGLE library + adom-lbr hub, generated from this page's KiCad sources · Ray 2mo ago
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ISO7221

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.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); iso7221.step / iso7221.glb are 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).

Datasheet PDF