What this supervisor does on your board
The MAX807MEUE is a battery-backup supervisor IC from Maxim Integrated, designed to monitor a single 5V supply rail and hold a microprocessor in reset until the supply stabilises. It asserts both active-high and active-low reset outputs, giving the designer flexibility to match the reset polarity of the downstream processor or FPGA. The reset timeout is a minimum of 140ms, long enough to let most power supplies settle before the CPU starts executing code.
Sourcing and lifecycle — active, but watch the RoHS flag
This part is listed as RoHS non-compliant. If your assembly line or end-customer requires lead-free solder, you will need a waiver or an alternative part. For legacy builds or military/industrial contracts that explicitly allow tin-lead finishes, this is not an issue — but verify your own exemption status before committing the line.
Threshold and timeout — what the numbers mean for your design
The 140ms minimum reset timeout is a fixed delay, not programmable. It is long enough to cover most linear and switching regulator start-up times, but if your supply has an unusually slow ramp (e.g., a large capacitive load on a low-dropout regulator), verify that the rail is stable within that window. If the timeout expires before the rail is fully settled, the processor may start executing before the supply is within tolerance. Having both active-high and active-low reset outputs means you can drive the reset pin of any common processor without an external inverter. Many modern MCUs use active-low reset; some FPGAs or legacy CPUs use active-high. This part covers both cases from a single IC, saving a logic gate and a trace.