What's good about the reset circuit? Many people may think so. Simple capacitive Reset, I believe everyone knows how to use it. I've always thought so, too. Later in the LSD of a msp430f449 development Board to see its reset circuit, see the circuit more than a 1n4148 diode, the role of the diode I once thought is a protective effect, until recently on the Internet to see a netizen's wonderful description, just know the true role of the diode.
The netizen is saying this:
As long as the power is switched on, the capacitor will "gradually become fully charged" and this process must be done to ensure that the CPU is correctly "RESET".
When the capacitor is fully charged, we disconnect the power switch, where does the electricity in the capacitor "go"? More than n devices are connected between VCC and GND, and all the devices say to it: "Give me your power, I can hold on." "Capacitance said:" To you no problem, but I have a mother on the head of a power to stop my Giro, you do not worry, I slowly put the electricity to you. ”
When the capacitor was just going to put the electricity through the pull-up resistor, the power switch was suddenly switched on. The CPU starts to flush the capacitance roar: "Grandson!" what happened to the charging process for Y? I'm going to reset it! " Capacitor does not dry: "Nonsense, my last charge of the electricity has not been put on the power of the mother again!" CPU urgent: "Then what do I do?" I have to reset it! The capacitance of the eyeball a turn: "What do you do, die you!"
If this diode is available, the voltage on the capacitor can be released quickly to ensure that the reset signal is correct. This is the true role of the diode.
Reset Circuit Analysis