AP4470

The AP4470 is an ultra-low consumption power management chip that integrates a step-up DC-DC converter and hysteresis comparators. The AP4470 requires only 0.20V input to start boosting without the need for an external transformer. The AP4470 has hysteresis operation switch that can control the power supply for target devices (sensors, wireless modules, LEDs) while protecting external storage (capacitors), and the target. 
 
1μW DC input is enough to startup the AP4470. Converted output is stored to external storage device and the AP4470 monitors the device. When the voltage of external storage reaches 3.3V, the AP4470 automatically starts supplying to the target device and stops supplying if the voltage drops down to 2.6V. Overvoltage protection function works at 3.55V.

2-types of power indicators offer reset function and trigger switch function. The trigger (Startup FLAG) is achieved by a signal that is output when DC-DC converter becomes active. The reset (Power Good) is a signal that indicates the AP4470 starts supplying, which means external storage’s voltage reaches 3.3V.
 
The AP4470 is ideally suited for several mW to several mW sources energy harvesting. This provides a self-powered wireless sensor node with simple hardware design.