I'm planning to use a MAX640 (Maxim 9 V -> 3.3 V Step-Down DC-DC Converter) to supply a couple of ICs with 3.3 V.
In active mode the current consumption of the ICs are around 20 mA and according to the datasheet the efficiency of MAX640 is around 90 %. Hence the total current consumption will be around (20 mA/ 90 %) = 22-23 mA, right?
But most of the time I want to shutdown ICs (and MCU) to get a consumption of maybe 10 uA.. looking at the datasheet (EFFICIENCY vs OUTPUT CURRENT) it is not even plotted... what will happen? Can I not use the MAX640 if I drop the current consumption that low?
A final question, anyone have a tip of a Step-Down DC-DC converter (or with equal functionality) that also can measure current consumption (analog, spi, i2c)