I designed a prototype for AVL(automatic vehicle locator)



You can see the MIC2941 and MIC2940 3.3 VDC on top of the board. This board is an interface between GSM modem which requires 1.5A @ 3.8VDC during transmit and a gps reciever board can't remember the current rating for it, not much anyway + active gsm antenna which are supplied by the 3.3 MIC2940 LDO regulator.
I supplied the circuit from car battery 12VDC and regulate it down to 3.3vdc for parts mentioned above.
I had no problems with heating what so ever, i ran the board conteniously for 4 hours, the transmission period is every 1 second I send SMS message to a center, the modem is online all the time communicating with the gsm company.
I used same regulator recomended by manufacturer of GSM modem so I didn't bother checking for maximum rating required for regulator.
Only explanation I could think of is that the MIC2941A uses a switching mechanism to be so efficient. I looked at the datasheet but it looks like it is linear regulator. The whole point is that I kept cost and space to minimum.
Actually when I ordered the part I asked about any heat sink requirements from distributors in south africa and they said I won't be needing any. I didn't beleive them of course till I tried it for myself.
can you explain that guys?
Regards
mahmood