Passes two logic signals across a galvanic barrier: one channel in each direction. Each side has its own supply (VCC1, VCC2) and ground, and the SiO2 capacitive barrier isolates them while data crosses at up to 100 Mbps, so a controller drives an isolated bus or gate driver without a shared ground. The narrow SOIC-8 (D) is rated 3000 Vrms; the wide-body DW option reaches 5000 Vrms. Common on isolated RS-485, SPI, and power-stage control.

Pinout

Pin	Name	Type	Function
1	VCC1	power_in	Side-1 power supply. 2.25 V to 5.5 V. Bypass to GND1 with a low-ESR ceramic capacitor (typ. 100 nF) placed close to the pin.
2	OUTA	output	Channel A isolated digital output on side 1 (ISO7721 has channel A flowing from side 2 to side 1). Push-pull CMOS output referenced to VCC1/GND1. Default state is HIGH on power/signal loss (LOW on the F suffix option).
3	INB	input	Channel B digital input on side 1. CMOS/LVCMOS-compatible logic input referenced to VCC1/GND1, driving isolated OUTB on side 2.
4	GND1	power_in	Side-1 ground reference for VCC1. Isolated from GND2 by the SiO2 capacitive isolation barrier.
5	GND2	power_in	Side-2 ground reference for VCC2. Isolated from GND1 by the SiO2 capacitive isolation barrier.
6	OUTB	output	Channel B isolated digital output on side 2. Push-pull CMOS output referenced to VCC2/GND2. Default state is HIGH on power/signal loss (LOW on the F suffix option).
7	INA	input	Channel A digital input on side 2 (ISO7721 has channel A flowing side 2 -> side 1). CMOS/LVCMOS-compatible input referenced to VCC2/GND2, driving isolated OUTA on side 1.
8	VCC2	power_in	Side-2 power supply. 2.25 V to 5.5 V, independent of VCC1. Bypass to GND2 with a low-ESR ceramic capacitor (typ. 100 nF) placed close to the pin.

Key specifications

Parameter	Value
Type	Dual-channel digital isolator (1 forward + 1 reverse)
Isolation	3000 Vrms (SOIC-8 D)
Data rate	Up to 100 Mbps
CMTI	100 kV/us (typ)
Supply (each side)	2.25-5.5 V
Default output	High or low (part suffix)
Package	SOIC-8

Ordering variants

Same part, different packaging or reel option.

ISO7721DR (SOIC-8, default-high)
ISO7721QDRQ1 (SOIC-8, automotive)
ISO7721DWR (SOIC-16W, 5000 Vrms)

CAD (KiCad official)

Symbol: Isolator:ISO7721D (KiCad official)
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOIC-8 (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Texas Instruments datasheet (51 pp, sha256 fb039c00ceb601b9, 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