3750Vrms isolation in a 20-SSOP — what it buys you
The ADUM1440ARSZ is a 4-channel, unidirectional digital isolator from Analog Devices' iCoupler series, using magnetic coupling to deliver 3750Vrms isolation in a 20-SSOP package. The four channels are all oriented Side 1 to Side 2 (4/0), so this variant is strictly one-way — no bidirectional or mixed-direction option in this order code. Data rate is rated at 2 Mbps, with typical rise/fall times of 2 ns and a maximum propagation delay of 180 ns in either direction. That puts it in the low-to-mid speed isolation segment — think GPIO isolation, I2C bus repeaters, or slow SPI links, not high-throughput data streams.
Unidirectional channels — design-in check
With all four inputs on Side 1 and all outputs on Side 2, this part is a straight signal-forwarding isolator. No bidirectional data paths, no direction-control pins. If your isolated interface needs a return channel (e.g., SPI MISO back to the controller), you will need a second device or a different ADUM variant with mixed channel directions. The 2 Mbps data rate and 180 ns propagation delay mean timing closure is straightforward for sub-1 MHz clocked interfaces. Pulse-width distortion is held to 8 ns max, so duty-cycle-sensitive signals like PWM or Manchester-encoded data retain reasonable integrity across the barrier. No isolated power is provided on-chip — each side requires its own local supply rail (2.25V to 3.6V). Plan for separate LDOs or isolated DC-DC modules to power the secondary side if the primary rail is not available there.