arduino interfacing with sim900 module!

[ali ghafoor]

sim900 needs 2 amperes during transmit burst..so arduino 5v pin cannot provide this much current..therefore i selected mic29302wt voltage regulator to drive sim900 which is capable of providing 2 amp current..now my question is that when 2 amp current is drawn from regulator during transmit burst how much current is drawn from 5v pin of arduino(i am using arduino's 5v pin as input power supply for regulator..and arduino is powered up via usb)?? because if current drawn from arduino exceeds its limits i will end up with my arduino burnt...so please provide me with the answer...how much current is drawn from arduino 5v pin during transmit burst?? thanks in advance

 

[g_shyam1682]

Hi friend,

Yes, you are right that SIM900 need 2 amperes during transmit burst, but it is only for 577 uS during 5.2mS duty cycle. So average current consumption is around 350 mA for GSM call and 450 mA for GPRS call.

To fulfill this type of current requirement from regulator (7805 with 1A), you should connect one electrolytic capacitor of higher value at supply terminal (Vbat) of SIM900 as Voltage backup.

In your post, you say arduino is powered up via usb. is it computer usb port or other? because computer usb port don't supply such current requirement, so don't use computer for power supply.

Regards,
Ghanshyam.