User Manual

JS7688-core-board manual Hangzhou Jotale Technology Co., Ltd www.jotale.com
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MP1482 stabilized power supply chip is used in the figure above, which can reach 2A output
current. Users can choose whether to use this model or not according to the actual situation. It is
not recommended to use "LDO chip" power supply, such as AMS1117, although the circuit design
of this kind of chip is simple, but the high current working efficiency is too low, high heat, it is
easy to cause the system power supply shortage, thus leading to the instability of the system.
3.2 About GPIO ports
The INPUT and output voltage of GPIO pin of MT7628/MT7688 is 3.3V.Some GPIO pins are
pull-up or pull-down inside the module to configure the system for MT7628/MT7688 startup.
Note that when the board is started, the GPIO pin labeled "pull up" in the "pin introduction"
should not be externally forced to pull down to a low level, and the GPIO pin labeled "pull down"
should not be externally forced to pull up to a high level, otherwise the system may be unable to
work normally. Other GPIO can be used according to the ordinary GPIO port.
3.3 Core board minimum system
The user only needs to connect the pins "GND" and "VDD3V3" of the core board to supply power
to the core board, and connect the three key pins "WDT_RST_N", "EPHY_LED2_N_JTMS" and
"WLED_N" with 10K pull-down resistance to the ground, and the system can work normally. This
module generally does not need to add heat sinks, but in order to improve the heat dissipation
efficiency of the system, please try to connect all "GND" pins of the module to the bottom plate
"GND" pins designed by the reader, so as to achieve better heat dissipation effect. Other pins,
such as debug serial port, network port, etc., can be added according to the user's own needs. If
you don't need them, just not connect them. Readers can refer
to“JS7628_base_board_xxxxx.pdf”(xxxxx is version number)base board schematic for designing。
4. The temperature when reflow
If the customer needs to design the base board with JS7688 stamp hole version module
through the reflow welding machine, pay attention to the reflow welding peak temperature do
not exceed 240℃, otherwise it may cause damage to JS7688 stamp hole module.
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