Neoway WM620 - VDD; ON_OFF Pin and Power-On Procedure; Table 3-2 Capacity Matching Power Failure Duration

WM620 Hardware User Guide
Copyright © Neoway Technology Co., Ltd
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Table 3-2 Capacity matching power failure duration
Power Failure Duration
Capacity
Encapsulation (X7R)
0.5 s
1.5 µF
0805
1.0 s
3.3 µF
0805
1.5 s
4.7 µF
0805
2.0 s
6.8 µF
1206
3.1.3 VDD
VDD_1.8V and VDD_2.6V are two power supply output pins, which can bear 20 mA in normal situation.
It is recommended to use them only for level shifting. The VDD_2.6V pin do not stop output after the
module enters the sleep mode.
3.1.4 ON_OFF Pin and Power-on Procedure
Prior to turning on the module, start the host MCU and complete the UART initialization. Otherwise
conflictions may occur during initialization due to unstable conditions.
ON/OFF is a low level pulse active input, used to turn on or off the module. It is pulled up to 1.8V
internally by a 200KΩ resistor and controlled by external OC. Figure 3-7 shows its pulse width and
power-on procedure.
When the WM620 is powered on, the VDD_2.6V pin will be pulled up and keep 2.6 V DC output. The
UART will send +EIND:8 after the module is powered on properly and send +EUSIM:1 after the USIM
card is identified. Then the module is ready to response AT commands. If the module does not identify the
USIM card, the UART will send +EIND:8+EUSIM:ERROR.
While the module is on, keep the ON_OFF pin low level for 2 seconds. Then the module enters shutdown
procedure and will be off in 5 seconds. Another approach to turn off the module is using AT commands.
For details, see Neo_WM620 WCDMA Module AT Command.
Keep ON_OFF low level or connecting to GND, and WM620 can start automatically when it is powered
on.
Figure 3-6 shows the circuit of ON_OFF controlled by high-level pulse.