Step Up problems with Sim900A

Other Hardware General Electronics
1

Hi,
I can't believe, some mouths ago i tested my system with atmega328 and Sim900A with a MT3608 Step Up.
I got 3.7 to 5v and all went right with different battery.
Today i've been tested the same system but i find that the MT3608 can't supply the right current(I think) to the Sim900a that go down on start.
I tried that with different battery with the same result.

I know that:

  1. Sim900A need to 2A peak to start
  2. If i use a usb power supply 1.5A system start without problem and the sim9000A starts.

Sorry for my english.

Thank's

2

Have you checked what your MT3608 is outputting?

Both voltage and current?

3

GSM transceivers require a good solid 2A peak current from its supply, and takes those peaks only during
transmit timeslices (normally 1 in 8 slices). I suggest adding a lot more decoupling (1000uF or so) and you
might protect the DC-DC converter from the pulse loading that's likely tripping it out.

4

Hi,
Thanks, i tried to do it, but i used two ceramic and i don't remember values.

This evening i'm going to check with two 1000uf electrolytic capacitors like you suggest.

I'll let you know.

Thanks.

5

Hi MarkT,
You don't know how you helped me, now it works with two 1000uf capacitors
Thank's.
Even if i knew the problem, i tried with different capacitor and probably I would have spent much time for other tests.

Thank's a lot.