Dual-rail supervisor for mixed-voltage boards
The Maxim Integrated DS1834AS+T&R is a multi-voltage supervisor from the EconoReset family that monitors two supply rails — 3.3V and 5V — with a single active-low, open-drain output. It asserts reset when either rail drops below its threshold and holds reset for a minimum of 200ms after both rails recover.
200ms reset timeout — what it means for system startup
The 200ms minimum reset timeout gives the power supplies and oscillators time to settle before the processor or FPGA comes out of reset. For a typical MCU with a crystal oscillator that needs 10–50 ms to stabilize, 200 ms provides comfortable margin. If the system has a fast-starting internal RC oscillator, the 200 ms delay may be longer than needed, but it does not cause harm — the processor simply waits. The timeout is not adjustable, so designs that require a shorter or longer reset pulse need a different supervisor or an external timer.
Surface-mount assembly is standard; no special reflow profile beyond the usual lead-free solder process is needed.
It is RoHS3 compliant.