I'm working on PWM power supply to supply a load which needs a constant current of 1 mA and 2.5V of operating voltage. The Pulse width Ton is 1 to 10 µs Maximum and Toff is 10 ms which results in a duty cycle of 0.1% Duty Cycle. The main purpose is to reduce the average current consumption of the whole device since it's needed only to operate during that short pulse. Now this comes to several issues. One is delivering a constant current using something other than a current limiting resistor whilst having a fixed supply voltage of 2.5 V. All that has to be provided during that Pulse. The rest of The time the power supply shouldn't consume more than 1 µA. A buck step-down converter is a good way to start for providing the right voltage and efficiency at a certain load, a device like TPS61098. One question about PWM switching buck converters. During the Toff time the current is supplied from inductor which means it needs to drain more current from the battery to maintain that constant and average load current. Am I correct here ? So in other words, the average output and the input current will be the same ideally. There are plenty of DC-DC converters, do you have any suggestion of one which can provide the behaviour I described? The circuit might be similar to LED driver where you can dim the LEDs using PWM input.
To conclude, there are two possible options here. One can control the buck converter using external PWM input and is able to operate with the timing i mentioned (1µs min enable time). The second option would be to supply my PWM timing generator from the buck converter and drive the load from the PWM generator. In both cases, the buck converter should be able to limit the current and voltage and consuming below 1µA averagely.
Your support is much appreciated.
Edit: The PWM pulses are generated from A MCU. I need a fixed voltage with a current limit. The device is considered linear. The voltage is 3V and is from a battery.