Forlinx FET6254-C, Hardware Manual

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Hardware manual
OK6254-C FET6254-C
www.forlinx.net
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Appendix
Appendix 1 Carrier Board Designing Instruction
Power
1. when you design carrier board PCB, please make your circuit can ensure the SoM to be powered firstly,
and carrier board powering controlled by VCC_3V3_SYS_PG output from SoM;
2. when SoM pins communicates with peripherals directly, please notice problem about current reflow. If
the SoM is not powered but peripheral powered firstly, it may cause current reflow to SoM, thus will
cause SoM failure. Please control the peripherals to be powered properly or add anti-reflow circuit;
3. some SoM pins are 1.8V, which should be noticed;
4. power supply to TF card should be under control;
5. display interface and USB device power consumption is relative high, please notice specially about the
PCB circuit layout and related over-current circuit;
6. PHY chip generally has multiple power supplying pins, such as AVDD, DVDD, DCDD_RGMII and so
on, please pay attention to each pin’s voltage. Generally, it needs magnetic beads for filtering, and please
ensure its around circuit capacitor’s value and quantity are enough;
7. we kindly suggest choosing 4.2V power for the 5G cellular module, if the voltage is too low and signal
quality is poor, the 5G module maybe disconnected or even restarted;
8. SDIO and UART for WiFi& BT is 1.8V;
9. if isolation is needed for CAN and RS485, both signal and power should be isolated.
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