Supervisor IC with battery-switchover logic for nonvolatile SRAM
The MAX691EPE+ is a single-channel battery backup circuit and supervisor IC from Analog Devices / Maxim Integrated, packaged in a 16-pin DIP (0.300" width) for through-hole assembly. It monitors a single supply rail at a 4.65V threshold and asserts a reset output when the monitored voltage drops below that level. The reset outputs are available in both active-high and active-low polarity, each driven by a push-pull stage — no external pull-up resistor is needed on either output. The reset remains asserted for a minimum of 35 ms after the supply returns above the threshold, providing a clean power-good window for the downstream processor or memory.
The 4.65V threshold is set for a nominal 5 V rail. On a 5 V ±10 % supply, the circuit triggers a reset before the rail drops below the valid operating range of most 5 V logic and SRAM — the supervisor acts before the data in a battery-backed RAM becomes corrupt. The 35 ms minimum reset timeout is long enough to let the supply stabilise after a brown-out or power-up transient, but short enough that the system does not stall unnecessarily on a brief glitch. The single-channel monitor suits designs that need only one voltage rail supervised — typical in embedded systems where a single 5 V supply powers the core logic and battery-backed SRAM, and the supervisor handles both the reset generation and the battery-switchover function.
Through-hole DIP package and temperature grade
The 16-PDIP (0.300" body width, 7.62 mm) is a through-hole package that fits standard 0.100-inch pitch prototyping boards and sockets.