Power Supply (including backup battery) for Tracker System,

My requirement are:
1. Volts: 4.2, Max current 2A, for SIM300, GPS-M90, some relays and other circuitry
2. Volts: 3.3, for SD Memory card, current consumption is minimum

Circuit will take power from Car battery (12V), I need another backup battery in case of main battery cutoff, circuit will automatically switch to backup battery if main battery cuts off..

I am thinking of using Li-Ion battery, but unable to select voltages and current rating for battery.

I have built other circuitry and it is working perfectly, I am providing the power to the circuit from Power Supply Unit (circuit is currently on my desk ).

Only power supply section is need to be designed, And i am not good with electronics, So i need help.
My requirement are given above, suggest me design.
Need an Efficient Power supply design with a backup battery for the tracker.

Thanks.

Re: Power Supply (including backup battery) for Tracker Syst

you could use this for the car battery (12V) to the 4.2V at 2A.

Creating GSM Power Supply from TPS54260

**broken link removed**


This is not high enough current but if you can find something at 2A would be ideal.
https://focus.ti.com/docs/prod/folders/print/tps2115a.html

maybe two low forward drop diodes with the cathodes connected could act as your power mux.

Re: Power Supply (including backup battery) for Tracker Syst

I need a simple solution. With minimum component count.
I am considering this bq24105
**broken link removed**

Waiting for more suggestions from your side.

Re: Power Supply (including backup battery) for Tracker Syst

Hi

Use LTC4412 Ic for switching between main supply and backup battery

See LTC4412 DS for circuit & application

All the best

Bobi

Re: Power Supply (including backup battery) for Tracker Syst

This is the circuit.
**broken link removed**

only the power supply section remains.
Need assistance,
Circuit will operate on 4.2V and 2.5 A,

Power supply sources:
- 12Volt car battery,
- And a backup battery if main car battery is not available

I am confused that how it all fit together??
Help needed to complete this circuit.

Thanks.

Re: Power Supply (including backup battery) for Tracker Syst

LTC4412 Power path management IC,
TPS54260 Buck Regulator,

Now i need a Charger IC that can be charge LIPO 2CELLS pack rated at 7.4output voltages and 600mAh??
suggest an IC suitable for automotive application (and low cost solution also)