Product Info

LTE Standard Module Series
EC21 Hardware Design
EC21_Hardware_Design 45 / 120
3.7. Power-on/off Scenarios
3.7.1. Turn on Module Using the PWRKEY
The following table shows the pin definition of PWRKEY.
Table 7: Pin Definition of PWRKEY
Pin Name Pin No. I/O Description Comment
PWRKEY 21 DI Turn on/off the module
The output voltage is 0.8V because of
the diode drop in the Qualcomm chipset.
When EC21 is in power down mode, it can be turned on to normal mode by driving the PWRKEY pin to a
low level for at least 500ms. It is recommended to use an open drain/collector driver to control the
PWRKEY. After STATUS pin (require external pull-up resistor) outputs a low level, PWRKEY pin can be
released. A simple reference circuit is illustrated in the following figure.
PWRKEY
4.7K
47K
≥ 500ms
10nF
Turn-on pulse
Figure 10: Turn on the Module by Using Driving Circuit
The other way to control the PWRKEY is using a button directly. When pressing the key, electrostatic
strike may generate from finger. Therefore, a TVS component is indispensable to be placed nearby the
button for ESD protection. A reference circuit is shown in the following figure.