Op Amp Idles To Save Power In Smoke Detectors, Other Sensors

With its power-saving mode, the LMV422 operational amplifier lets designers reduce power consumption while maintaining an active circuit. Thus, there's faster turn-on times in smoke detectors and other sensor interface applications where reaction time is critical. This dual rail-to-rail op amp can be switched between its normal 400-µA/channel, 8-MHz mode to an economical 2-µA/channel, 27-kHz mode via an external control pin. Running the amp in its low-power operational mode reduces overall power consumption while maintaining necessary charges on coupling capacitors. It also shortens the time needed to stabilize the signal after switching to high-power mode. The chip has a 5-pA input bias and runs off supplies from 2.7 to 5 V. Its common-mode rejection ratio is 85 dB. The LMV422 costs $1.20 in 1000-unit quantities.