Low current PIC

Status
Not open for further replies.
F

flatfootskier

Member
The last pic project I did (quite a while ago) I used a TDA3664 voltage regulator to get 5v. It had a quiescent current of less than 15uA & gave me great battery life with a low speed Xtal. IS this still the way to do it or is there some way a bit smarter.
 
best way to do it is use a battery that is compatible with the pic's voltage range, needing no regulation

for example a 3.7v Lithium cell, 2-4 Nimh in series, or even a 3v lithium coin cell
 
Sorry, I should have cleared that up - it has to come from a lead acid 12V cell - which drives a 100A motor occasionally for short periods. Suprisingly, the Wh load over a day from a dribbling 7805 is much greater than the short 100A bursts
 
yea those old linear regulators are wasteful creatures.

how much current does your PIC circuit need when it's fully operating? you could use something like a shunt regulator to siphon off a 1mA (or less) of current from that 12v cell, and power the PIC from that. then use one of the pic's pins to enable a higher power regulator (look for LDO regulators with a shutdown pin) when you need to drive 'user interface components' like LEDs and other displays. this way the wasteful high-current linear regulator will only be in circuit when your pic needs to be fully operational. in standby, the shunt regulator will only siphon enough current to operate the pic in bare bones mode.
 
flatfootskier said:
Sorry, I should have cleared that up - it has to come from a lead acid 12V cell - which drives a 100A motor occasionally for short periods. Suprisingly, the Wh load over a day from a dribbling 7805 is much greater than the short 100A bursts
Click to expand...

As your previous regulator only used 15uA, that should be perfectly fine from a lead acid battery.
 
You could also save power by choosing a PIC18F series microcontroller, these have "nanoWatt Technology" - this provides more modes for power saving by turning-off some features etc.
 
picasm said:
You could also save power by choosing a PIC18F series microcontroller, these have "nanoWatt Technology" - this provides more modes for power saving by turning-off some features etc.
Click to expand...

The 12F and 16F chips have "nano watt" listed on their datasheets as well.
 
The 12F and 16F chips have "nano watt" listed on their datasheets as well.
Click to expand...
Yes, you are right, but looking at some of the data sheets it appears that some don't have as many of the "nanowatt" features as others.
For example, in the 16F range, the two speed startup option is only available on a few devices such as the 16f87,88 whereas more of the 18F range have all of the features.

I think they just keep adding more power saving features to newer devices whilst still using the same "nanowatt technology" name.
 
It's still pretty pointless in this thread, as the power source is a lead acid battery - hardly need for 'nanowatt' technology?.
 
picasm said:
The original thread was "Low current PIC" and the op mentioned using a regulator with a quiescent current of less than 15uA.
Click to expand...

And then mentioned it's powered by a lead acid battery!.
 
I have to agree. Lead acid is plenty of power if you run a pic at low speed, which he said he did as well. 15uA for the regulator, leave it in..
 
Status
Not open for further replies.

Similar threads

  • Question
pic port expander
2
Replies
28
Views
5K
Pommie
P
E
  • Question
High res cap meter with PIC 16F628
Replies
7
Views
2K
Elekktrishun
E
G
  • Question
Constant current circuit
Replies
18
Views
3K
danadak
T
  • Solved
Can u help me with this counter!!! (PIC18F46K22)
Replies
8
Views
1K
Ian Rogers
A
  • Question
PIC: Dumb question re banksel
Replies
11
Views
4K
augustinetez
A
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…