High efficiency voltage regulation when idle.

[johanfo]

Hi,

I'm asking this forum in order to solve a little electrical engineering problem of mine.

I have a PIC18F14K50 which requires a ~2-5.5V supply. My battery powerunit provides 7.5V.

So, it is easy to reduce the voltage by a couple of diodes, however, at the low currents, the diodes only drop around 0.3V, leading to a lot of diodes, and also, when the current increases, so does the drop.

In general, this could also be solved by a voltage regulator, however, I'm really trying to keep the current drawn at a absolute minimum. At the moment, the pic is 90% in its idle state, and only drawing 6 uA at this level. Adding a regular voltage regulator will send the idle current skyhigh.

So, how do I reduce the 7.5 V to something that the PIC can tolerate, and at the same time keep extreme low idle-currents?! Any ideas will be greatly appreciated.

best regards
JF

 

[FvM]

Some parts that perform quite well in the low quiscent current range

Linear LT3008, LTC3388
TI TPS62120

 

[johanfo]

The knowledge of people here is immense..Thanks a lot... These look really nice!!

 

[dependableelectrical2012]

Hi,

I'm asking this forum in order to solve a little electrical engineering problem of mine.

I have a PIC18F14K50 which requires a ~2-5.5V supply. My battery powerunit provides 7.5V.

So, it is easy to reduce the voltage by a couple of diodes, however, at the low currents, the diodes only drop around 0.3V, leading to a lot of diodes, and also, when the current increases, so does the drop.

In general, this could also be solved by a voltage regulator, however, I'm really trying to keep the current drawn at a absolute minimum. At the moment, the pic is 90% in its idle state, and only drawing 6 uA at this level. Adding a regular voltage regulator will send the idle current skyhigh.

So, how do I reduce the 7.5 V to something that the PIC can tolerate, and at the same time keep extreme low idle-currents?! Any ideas will be greatly appreciated.

best regards
JF

https://www.linear.com/product/LT3008

This is useful to you..

 

[johanfo]

Just realized that these devices are REALLY small! Not something to prototype with unless you are an ant! 2mm width is not much at all! How do you solve these kind of problems?

 

[FvM]

It's a bit difficult to handle on bread boards. Personally I do most prototyping on commercially manufactured PCB. SMD adaptors are an option to connect very small packages in bread boards.