Comparator with on-chip voltage reference
The MAX931CSA+T is a single comparator from Analog Devices that integrates a precision voltage reference on-chip, eliminating the need for an external reference diode in threshold-detection circuits. It draws a maximum quiescent current of 4µA, making it suitable for battery-powered or always-on monitoring where supply current is the binding constraint. The 12µs propagation delay sets the response ceiling — for a 50/60 Hz line monitor or a slow-changing sensor threshold, this is more than adequate; for a high-speed overcurrent trip, a faster comparator would be needed.
Supply range and output drive
The single-supply range spans 2.5V to 11V, or ±1.25V to ±5.5V in split-supply mode, covering common 3.3V, 5V, and ±5V rails without an extra regulator. The CMOS/TTL output sinks or sources 0.015mA typical at 5V — enough to drive a logic gate input or a low-power LED indicator, but not a relay coil directly. Built-in 50mV hysteresis prevents output chatter when the input signal crosses the threshold slowly or carries noise — a common issue in battery-monitor and thermostat circuits.
Package and temperature grade
Housed in an 8-SOIC package (0.154" body width, 3.90mm), the footprint matches the industry-standard SOIC-8 land pattern — no special pad geometry or thermal vias required.
CMRR and PSRR are both 80dB typical, meaning the threshold accuracy holds up well against common-mode shifts and supply ripple — relevant when the comparator shares a rail with a switching regulator.