Low power consumption 5V regulator required

[SPDCHK]

I’m doing a project for a friend that requires LED’s to flash at different rates depending on switch contact positions. The circuit and programming is done (I used a 12F675 PIC)

The circuit will be used underground and runs off batteries.

I did the designs with both a 7805 and then a LM317 voltage regulator. The 7805 regulator uses about 4mA just on the regulator, and the LM317 about 3.7mA. The requirement is for the circuit to run off the battery power supply for as long as possible.

Is these an alternative 5V regulator chip that I can use? Something that will draw less than 4mA? The circuit consumption is less than 20mA (that includes the 4mA used by the regulator).

Thanks

 

[KJ6EAD]

What is your input voltage?

 

[mvs sarma]

You can safely work with 3 dry cells, alkaline type (like Duracell) at 4.5V and no regulator needed.
There is no point in using 9V battery, using regulator to waste energy bringing to 5V. more than the self current, the series drop at real load is more consuming.

 

[SPDCHK]

What is your input voltage?

The idae is to use 6-8 cells rechargeable. About 9.6V (Max)

 

[crutschow]

You might look at these micropower regulators from National. They use only 75µA nominal.

 

[SPDCHK]

You might look at these micropower regulators from National. They use only 75µA nominal.

There we go! Thank you crutschow

 

[Sceadwian]

mvs sarma, without regulation LED brightness won't be easily controllable, neither will the timing rate of the LED flashing if the internal oscillator is used, they're VCC sensitive so it would flash at different rates/brightness depending on the battery state. You might want to look at buck converters if you're going to use a 9V input, the gains in efficiency of using a switching regulator will be much higher than even a low current linear regulator. Give Lithium batteries a chance to as capacities are much better and you only need three cells for the same voltage an 8cell Nimh would use.

 

[mvs sarma]

I agree. it is presumed that the PIC would do the contol job. but a s read the op's first post, perhaps he is using relay dive. In such case the power supply for , say, chain LEDs should be a special switch mode or pwm drive.