3G vs 2G cellular module for a professional power sensitive GPS tracker?

[JonSea]

The power switch is a MIC2025-1, which can handle 500mA which was enough for the GPS module.

 

[Nigel Goodwin]

Yes, those were the sort of things I found - but not big enough for the 2A pulses for a GSM modem.

 

[be80be]

Well I was thinking I can get the phone number to show up for the SIM900 I got it from radio shack for about nothing there was no papers nothing and google just showed people having the same problems but I read that it would reset if you wasn't using a 2 amp supply. I never tried it that way now i'm wondering if thats what was happping all alone.
cause I have had everything work up to the point where I start sending text then it would stop doing anything.

I would get it was on t-moble and stuff and show it had service and a working number but as soon as I sent it a text or used it to send a text nothing.

 

[JonSea]

Yeah, those modules really draw the juice!

 

[Nigel Goodwin]

Well I was thinking I can get the phone number to show up for the SIM900 I got it from radio shack for about nothing there was no papers nothing and google just showed people having the same problems but I read that it would reset if you wasn't using a 2 amp supply. I never tried it that way now i'm wondering if thats what was happping all alone.
cause I have had everything work up to the point where I start sending text then it would stop doing anything.

Yeah, they take (at least) 2A pulses - if you don't have a decent PSU then it won't work - as soon as it tries to transmit the voltage drops and the unit resets.

I'm powering my SIM800L models either from two 18650 batteries in parallel (at the moment), or from a higher voltage via a little switch-mode PSU with an LCD display on it. In either case there's plenty of power available for the modem - I've also got a 1000uF capacitor right next to the power inputs of the module, and space on the board for fitting a 'BEST' capacitor in case of a need to use a long life (and high internal resistance) Lithium battery.

 

[JonSea]

Nigal, this is a load switch designed for USB C - 2 amps at up to 36 volts. Pity it's some micro package! There are several variants. The one I looked at is US$1.22 at Digikey.

TCK30xG by Toshiba.

 

[Nigel Goodwin]

Nigal, this is a load switch designed for USB C - 2 amps at up to 36 volts. Pity it's some micro package!

The micro package would be a problem

The dual-FET I used switches 6A, and is in a sensible sized SM package - but does require a few resistors to make a high level switch out of it.