大家好 ,现在用2808,请问下2808上电时候内核和外核,掉电时内核与外核有没有要求?比如先上内核后上外核。。。谢谢
Jones Chen:
No requirements are placed on the power up/down sequence of the various power pins to ensure thecorrect reset state for all the modules. However, if the 3.3-V transistors in the level shifting output buffersof the I/O pins are powered prior to the 1.8-V transistors, it is possible for the output buffers to turn on,causing a glitch to occur on the pin during power up. To avoid this behavior, power the VDD (core voltage)pins prior to or simultaneously with the VDDIO (input/output voltage) pins, ensuring that the VDD pins havereached 0.7 V before the VDDIO pins reach 0.7 V.
Additionally it is recommended that no voltage larger than a diode drop (0.7 V) should be applied to anypin prior to powering up the device. Voltages applied to pins on an unpowered device can bias internal p-njunctions in unintended ways and produce unpredictable results.