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SIM900D Hardware Design
Turn on impulse
The power on scenarios illustrates as following figure.
VBAT
PWRKEY
(INPUT)
STATUS
（OUTPUT）
Serial Port
When power on procedure completes, the SIM900D will send out following result code to indicate the module is
ready to operate when set as fixed baud rate.
RDY
This result code does not appear when autobauding is active.
SIM900D_HD_V1.02
4.7K
Figure6: Turn on SIM900D using driving circuit
S1
TVS1
Figure7: Turn on SIM900D using button
Pulldown >1s
V
<1.2V
IL
Undefined
Figure8: Timing of turn on system using PWRKEY
PWRKEY
47K
PWRKEY
Delay > 2.2s
V
> 2.6V
IH
V
> 2.7V
OH
25
Active
09.04.2010
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