Getting serious about power consumption in small, battery-powered wake-up circuits means dropping the clunky old 555s and baling wire in favor of some modern low-voltage analog building blocks. Yes, these same functions can be jury-rigged from AUP logic gates, but the penalty will be high shoot-through supply currents as the gate input voltages hover around the threshold level. The circuits presented here are designed with slow-moving analog signals in mind and don’t exhibit that problem.