ISO7731FDW

Texas Instruments

Texas Instruments ISO7731FDW, General Purpose digital isolator, 3-channel unidirectional, Capacitive Coupling, 100Mbps data rate, 5000Vrms isolation, 2.25V~5.5V supply, -55°C~125°C, 16-SOIC.

Texas Instruments ISO7731FDW
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Technical specifications

ISO7731FDW specifications
Parameter / AttributeSpecification / Value
TypeGeneral Purpose
Channel typeUnidirectional
MountingSurface Mount
Supply voltage2.25V ~ 5.5V
Voltage - isolation5000Vrms
Isolated powerNo
Operating temperature-55°C~125°C
Pulse width distortion4.9ns
PackageTube
Data rate100Mbps
TechnologyCapacitive Coupling
Case16-SOIC (0.295\", 7.50mm Width)
Channels3
Inputs - side 1/Side 22/1
Rise (Fall time)1.3ns, 1.4ns
Propagation delay tpLH (tpHL)16ns, 16ns
Common mode transient immunity85kV/µs

Technical details

5000 Vrms isolation — the safety-barrier spec that decides fit

Its headline rating is 5000 Vrms isolation voltage, which qualifies it for reinforced insulation in mains-connected industrial and medical equipment where a safety barrier is required between the high-voltage and low-voltage domains. The part supports a 100 Mbps data rate, matching the throughput of common serial buses like SPI, UART, and CAN FD without adding latency.

85 kV/µs CMTI — why it holds up in motor drives and inverters

In a motor-drive or solar-inverter environment where IGBT or SiC switching edges produce fast voltage transients across the isolation barrier, a low CMTI part can falsely toggle its output. This rating means the ISO7731FDW maintains data integrity through those events. Propagation delay is symmetrical at 16 ns max for both low-to-high and high-to-low transitions, with pulse-width distortion held to 4.9 ns max — tight enough for timing-sensitive interfaces like isolated SPI clock lines.

3-channel unidirectional — 2 forward, 1 reverse

The channel configuration is 2 inputs on side 1 and 1 input on side 2, all unidirectional. This suits applications where two data lines cross the barrier in one direction (e.g., TX and clock from a controller to a peripheral) and one line returns in the opposite direction (e.g., RX or fault feedback). The part does not include an integrated isolated DC-DC converter — isolated power must be supplied externally.

ISO7731FDW
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