Hi,
In many case, the power supply remain a problem.
I've found the 'MC34063' from OnSemi into a GSM and GPS Car Battery Charger.
This DC-DC Converter was specifically designed to be incorporated in Step−Down and Step−Up and Voltage−Inverting applications.
http://www.onsemi.com/
There are a lot of applications notes about it on the web (include pcb design) and this address refer to a components calculator: http://www.nomad.ee/micros/mc34063a/index.shtml
I hope this help you in future dev.
Bests regards.
In many case, the power supply remain a problem.
I've found the 'MC34063' from OnSemi into a GSM and GPS Car Battery Charger.
This DC-DC Converter was specifically designed to be incorporated in Step−Down and Step−Up and Voltage−Inverting applications.
http://www.onsemi.com/
Features
• Operation from 3.0 V to 40 V Input
• Low Standby Current
• Current Limiting
• Output Switch Current to 1.5 A
• Output Voltage Adjustable
• Frequency Operation to 100 kHz
• Precision 2% Reference
There are a lot of applications notes about it on the web (include pcb design) and this address refer to a components calculator: http://www.nomad.ee/micros/mc34063a/index.shtml
I hope this help you in future dev.
Bests regards.