Smart LTE Module Series
SC650T Hardware Design
SC650T_Hardware_Design 41 / 131
1. It is recommended to switch off the power supply for module in abnormal state, and then switch on
the power to restart the module.
2. The module supports battery charging function by default. If the above power supply design is
adopted, please make sure the charging function is disabled by software, or connect VBAT to
Schottky diode in series to avoid the reverse current to the power supply chip.
3. When the battery power is reduced to 0%, the system will trigger automatic shutdown, so the design
of power supply should be consistent with the configuration of fuel gauge driver.
3.5. Turn on and off Scenarios
3.5.1. Turn on Module Using the PWRKEY
The module can be turned on by driving PWRKEY pin to a low level for at least 1.6s. PWRKEY pin is
pulled to 1.8V internally. It is recommended to use an open drain/collector driver to control the PWRKEY.
A simple reference circuit is illustrated in the following figure.
Turn on pulse
PWRKEY
4.7K
47K
>1.6s
R1
R2
Q1
R3
1K
Figure 5: Turn on the Module Using Driving Circuit
Another way to control the PWRKEY is using a button directly. A TVS component is indispensable to be
placed nearby the button for ESD protection. A reference circuit is shown in the following figure.
NOTES
