Hej all,
I am planning to use MCP1640 battery boost regulator as power supply to PIC18F2420. My project is about to control 10K-Thermistor sensor. Reading ADC in active mode then go to sleep mode for a while using Timer1 and watch dog timer. I used IC power supply lm7805 but this is not suitable for 3 volt battery supply. The idea for my project is that MCP1640 can supply 3.3 Volt @ output current < 130mA so my question is it a good idea to use MCP1640 with PIC18F2420 to drive 3Volt AAAA battery? Or any one has done it?

 

It'll be fine.

 

The PIC18F2420 will work down to 2.0VDC. Why not run it directly off the battery?

Inserting the switcher will waste precious battery power and interfere with entering a low power sleep mode between readings.

 

I assumed he needed 3.3v for something...but you are correct. If he runs the thermistor ratiometrically, there is no need for a stable vdd.

 

Thanks for your reply . I am sorry for my bad English language. I should be more specific in this thread.. I used also LCD display (COG-BTHQ21605-02 )for showing my data. In my project. It uses about 2.8Volt as minimum. My problem is reducing the current consumption in sleep mode at least to 1 mA. Which I did not succeed in. Sorry may be I am wrong to choose MCP1640 because of unstable output voltage due to load. If I use only (may be a lithium battery) so how about battery protection circuit?

 

why not use the booster only for the display? Otherwise you need to run the PIC directly from battery in sleep mode, then turn on the booster periodically which is complicated. You need the right MCP1640, see the datasheet, for that.

Also maybe your coil isnt right for the high current, maybe your batteries arent suitable too.

Where is all that current going? How much is it?

You dont write enough information.

 

The sleep instruction is not complicated.