Author Topic: Which VR has the lowest quiescent current when DISABLED?  (Read 1062 times)

WhiteHare

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Which VR has the lowest quiescent current when DISABLED?
« on: October 21, 2016, 04:50:24 PM »
Today I put a TPL5010 onto my small experimental TH node and got it routed.  I'll use it as both watchdog and wakeup timer.  If tapping into a greater than 3.6v power source, I think the next step is to simply have the atmega328p wake up periodically and switch on a voltage regulator to charge up a ceramic capacitor and then switch off, as per JL's suggestion on another thread.  I want to keep component count low, though, mainly because routing is getting crowded.  So, preferably, the VR itself would have an ENABLE pin, and its quiescent current when DISABLED would be extremely low.  I'd prefer that rather than switching it on/off using a separate load switch.  Anyone have any favorites and/or suggestions for that kind of VR? 

When the atmega328p is ready to do actual work, like transmitting using the RFM69HW, it would first ENABLE the VR, just to be sure there's adequate current available.  After it's done and the capacitor is charged,  it would DISABLE again, pat the dog, and go back to sleep until the TLP5010 wakes it again.

Well, that's the plan anyway.  I'll do my own search, but it might inadvertently overlook such a VR that someone here has perhaps already found.
« Last Edit: October 22, 2016, 01:25:44 PM by WhiteHare »


WhiteHare

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Re: Which VR has the lowest quiescent current when DISABLED?
« Reply #2 on: October 21, 2016, 06:13:42 PM »
You found one here:
https://lowpowerlab.com/forum/low-power-techniques/low-power-and-rfm69hw-calculation-question/msg15870/#msg15870

Yup, that would work for a boost converter, but here I'm talking down converter.  Here's one with an ENABLE pin and just 10na ground pin current when disabled that might work:
http://www.ti.com/lit/ds/symlink/reg102.pdf
It provides 3.3v output and can accept up to 10V input voltage. 

[Edit:  Somewhat expensive on digikey, but I found it on Aliexpress for much less and just now ordered it:
https://www.aliexpress.com/item/Free-shipping-10pcs-lot-REG102NA-3-3-REG102NA-2-85-REG102NA-5-0-REG102NA-2-5/32589446061.html?spm=2114.13010208.99999999.264.tVeOPR

With e-packet delivery, they should arrive around the same time as the newly fabbed small nodes that will be upgraded to use it.

Another seller has them at $0.14/each, though with longer shipping time:
https://www.aliexpress.com/item/When-the-United-States-and-the-Dragon-REG102NA-SOT23-5-REG102NA-3-3-original-authentic-100/32733677298.html?spm=2114.13010208.99999999.264.bDIJBW

Since this thread is now moot, moderator may delete at his discretion.  ]


« Last Edit: October 21, 2016, 09:40:32 PM by WhiteHare »