Dual comparator with a built-in voltage reference
The MAX933ESA+T from Maxim Integrated packs two comparators and a precision voltage reference into a single 8-SOIC. The internal reference eliminates an external reference IC and its associated bypass caps, saving board space on dense mixed-signal PCBs. It targets threshold-detection applications—battery undervoltage lockout, overcurrent trip, window comparators—where the 50 mV hysteresis prevents chatter at the switching edge. The CMOS/TTL output stage drives logic inputs directly; no external pull-up resistor needed for CMOS rails. Supply range spans 2.5 V to 11 V single, or ±1.25 V to ±5.5 V dual. The 12 µs propagation delay is adequate for slow-changing analog signals like temperature or pressure transducer outputs.
The 50 mV hysteresis is set internally—no external resistors for positive feedback. The 10 mV max input offset at 5 V is the threshold accuracy at the comparator input. 80 dB CMRR and 80 dB PSRR are typical figures—adequate for rejecting supply ripple and common-mode noise in a 12-bit signal chain. If the input common-mode range is exceeded, the output state is undefined; stay within the supply rails. Output current is specified at 0.015 mA typical at 5 V—this is a logic-level output, not a driver. Do not expect it to sink a relay coil or LED directly; buffer with a transistor or a logic gate.