trying to reduce current consumption on a 12HV615

[Heckler]

Well I tried to go back and correct the text I copied from the datasheet showing current consumption, but this forum would not let me...

the data sheet shows current consumption of
100 microamps nominal at 1MHz
and it drops to 1nanoamp in standby.

Is your current measuring equipment able to measure these small value current changes?? or are you expecting to see a bigger change?

[Max Power]

hmm... I'm nowhere near microamps, I'd love to be in the uA range. I'm powering the board at 12V, and using the pic's internal 5V shunt regulator. I've got a 510 ohm resistor between the power input and the pic. I have a diode on the 12V in, so it goes 12V in --> diode---> 510 ohm res ---> Pic. I also have two strings of LEDs picking up power after that diode, and the strings are switched to GND through a FET (BSH114). I'm PWMing the 2 fets. I also have a TVS to gnd (smaj24) on the 12V coming in. I figure that the LEDs aren't drawing any current when the FET is off, The TVS shouldn't be, the shunt regulator has got to draw some current, I'm thinking 4 or 5 mA. and then whats left is the pic, which is only driving the fets. I have a 10K pull down on the PWM line, and a 10K pullup to vcc on the switch input.

I'm measuring a current draw of about 12mA on the 12V line when the lights are off and the switch is open circuit. Chip running at 8Mhz with no napping = 12.6mA on my fluke DMM (300mA) setting. chip running at 4MHz with napping = 12.6mA.

[Darrel Taylor]

The shunt regulator will always draw the same amount of current whether the PIC is asleep or awake.
That current is always MORE than the most that will ever be used by the PIC, including output pins.

As the PIC draws more current, the regulator "Shunts" less to maintain the same voltage.
When asleep, the regulator draws the full amount, since the PIC is drawing ~nothing.

If you want low current, use an external LDO regulator, and a different PIC.

[HankMcSpank]

+1


I use an MCP1703 (available in many variants with differing voltage outputs), it's very low quiescent currrent.

In sleep, I'm getting about 6uA draw for my whole circuit (though there's a lot of trial & error changing pin IOs TRISs Analogue on/off shutting down peripheral etc to get it down to that!).

[Max Power]

Thanks everybody. I was slowly realizing the same thing on my own, but it's nice to hear from you guys.

I'll look into the MCP1703, or other low Q LDOs