UMTS/HSPA+ Module Series
UG89 Hardware Design
UG89_Hardware_Design 26 / 73
PWRKEY
4.7K
47K
10nF
Turn-on pulse
≥
500ms
Figure 6: Reference Circuit of Turing on the Module Using Driving Circuit
The other way to control the PWRKEY is using a button directly. When pressing the key, an electrostatic
strike may generate from the 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.
PWRKEY
S1
Close to S1
TVS
Figure 7: Reference Circuit of Turing on the Module Using Keystroke
The timing of turning on the module is illustrated in the following figure.