Author Topic: Using the MCP16251 with CR2032 battery. A good choice?  (Read 120 times)

doublec4

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Using the MCP16251 with CR2032 battery. A good choice?
« on: May 11, 2018, 11:10:40 PM »
Hi all,

So I recently made a two button remote with a regular pcb trace Moteino. I used the MCP16251 boost regulator with a CR2032 battery to power it (directly to the 3.3V pin on the Moteino). In the programming I used sleep mode for the MCU and radio sleep for the radio. The unit wakes up on a button press and only stays awake for a few seconds to receive the ack and a possible error code from the receiver.

The first time I tested the remote, it seems to work fine. I got a little carried away and was pressing buttons over and over for a little while. Then I left the unit to sleep, came back a few hours later and the remote was dead. When I removed the battery the voltage eventually came back up to 3V on the coin cell but when inserted back into the remote I believe it can no longer support enough current for the radio to work. Pressing a button will not send a packet and the unit seems unresponsive. When I calculated the battery life before designing and building the remote I estimated that the battery would last ~1 year with ~2 button presses per day. However, by aggressively using the remote for a short period of time, does this somehow drain the battery faster than using it with longer intervals of rest in between?

Also, the MCP16251 chip has an enable/shutdown pin... one version of the chip has input to output disconnect when this pin is grounded, and the version that I have has input to output bypass when the enable pin is grounded. I'm assuming this means that voltage is no longer regulated and the datasheet says current consumption drops to ~0.6uA in this state. Right now I am not using this feature, but would it be as simple as connecting the enable pin to a digital I/O on the Moteino and pulling the pin low before sleeping the Moteino? Then the interrupt could wake the Moteino, I could pull the enable pin high again and the regulator would kick back on to boost for a reliable 3.3V output? Would this be better than leaving the boost regulator on the entire time? Or is it more complicated than this? Thanks!

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