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Another way to control the PWRKEY pin is to use a button directly. When you press the button,
electrostatic strike may be generated from finger. Therefore, you must place a TVS component nearby
the button for ESD protection. Additionally, a 1 kΩ resistor is connected in series to PWRKEY for ESD
protection. A reference circuit is shown in the following figure.
The timing of turning on the module is illustrated in the following figure.
VBAT (Typ. 4.0 V)
PWRKEY
LDO18B_1V8
Others
NOTE
1.
When the module is turned on for the first time, its turn-on timing may be different from that shown
above.
2.
Make sure that VBAT is stable before pulling down the PWRKEY pin. It is recommended to drive
PWRKEY low after VBAT reaches 4.0 V and remains stable for 30 ms. PWRKEY pin cannot be
pulled down all the time.
SG560D_Series_Hardware_Design
S1
TVS
Close to S1
Figure 7: Turn On the Module Using Button
Figure 8: Turn-on Timing
R1
PWRKEY
1K
Turn-on pulse
≥ 1.6 s
ACTIVE
Smart Module Series
M odul e
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