I am using a single NiMH cell to run a microcontroller and some LEDs at around 3.5 Volts. The NiMH cell is charged by a low power solar cell. When the NiMH is being trickled charged from the solar cell, I need the boost converter to remain in shutdown mode until the NiMH cell voltage rises to around 1.2 volts. I used a tps61220 but it switches on when the NiMH is at 0.7 volt. At this voltage, the battery does not have enough juice for the dc/dc output to stabilize. Note that the LEDs at the output are controlled by the micro. So the output load is just the micro. The micro will switch on the LED later when the NiMH is charged and it is night time. So, I need a boost converter which can remain shut off until the solar cell trickle charges the NiMH to 1.2 volts.
Low power solar cell ----> NiMH cell -> boost converter -> micro & leds
