User's Manual

Smart Machine Smart Decision
SIM7100A_User Manual_V1.01 2014-12-11
26
Cf must be mounted.
In addition, in order to get a stable power source, it is suggested to use a zener diode of which reverse
zener voltage is 5.1V and dissipation power is more than 500mW.
Table 8: Recommended zener diode models
No. Manufacturer Part Number Power Package
1 On semi MMSZ5231BT1G 500mW SOD123
2 Prisemi PZ3D4V2H 500mW SOD323
3 Vishay MMSZ4689-V 500mW SOD123
4 Crownpo CDZ55C5V1SM 500mW 0805
3.1.2 Recommended Power supply circuit
We recommend DCDC or LDO is used for the power supply of the module, make sure that the peak
current of power components can rise up to more than 2A. The following figure is the reference design of
+5V input power supply. The designed output for the power supply is 3.8V, here a linear regulator can be
used.
Figure 8: Reference circuit of the LDO power supply
If there is a big difference between the input voltage and the desired output (VBAT), a switching converter
power will be preferable because of its better efficiency, especially at the high current situation. The
following figure is the reference circuit. Note that DCDC may deprave RF performance because of ripple
current intrinsically.