Particle Argon 5V output when powered from Li-ion/Li-Po

Hardware
1

Hi community,

I am interfacing a 5V logic serial device with a Particle argon. A Li-ion battery is connected for backup.
As far as the USB is powered, I can use the USB pin on Argon to get 5V directly to my serial device (no issues faced in TX RX transmissions). But at the instant the USB is unplugged, I will lose my access to 5V through the USB pin.

Any solution to get 5V when the Argon is powered from battery.?
I can see the 3.7-Pin is internally connected to the battery +ve , Can I use a 5V booster directly from here.?

Thanks

2

There should be no reason why not - but remember that while you are on the LiPo, it can supply all the current your need (up-to its limits of course) but when you are USB, the charge current may not be enough to charge the battery AND power your 5V devices (it may also affect the charge management operation). So I suggest getting a boost convertor that has an !EN pin so that you can only turn it on when the USB 5V is gone. Use 2 diodes to stop any power feed back from each 5V source ie.

VBUS ------------>|---+---- 5VforIO
           |          |
          !EN         |
           |          |
LiPo+ --- Boost-->|---+

>|

is a small signal diode like a IN4001 or similar

3

Thanks @shanevanj
It seems to solve the complete issue!

Let me try with MAX756/MAX757 and will update!

Or have you worked with a similar boost converter to suggest one.?

4

take a look at something like this

I would put a pull down resistor on !SHDN (10K or so to drive the level below 0,4V when no no VUSB)

5

Nice module. This would certainly workout!! Thanks @shanevanj
Let me see the chances to get one here.