EN pin has a glitch free operation. The first timer will start counting at a rising threshold of EN, but will always reset if the EN pin is de-asserted before the first output
FLAG is released. Please refer section 7.3.1 of https://www.ti.com/lit/ds/symlink/lm3880.pdf
If the EN pulse width is less than the delay time, the FLAG does not response. The EN pulse should stay active during whole power-up sequence. If the EN is deasserted before the power-up sequence is completed, the device enters a controlled shutdown. Please refer 7.3.2 of http://www.ti.com/lit/ds/symlink/lm3880.pdf
Here is an example of the EN glitch function. Yellow is EN signal and Pink is FLAG 1 and green is FLAG 3. The glitch of the EN does not cause the shutdown of the Flag outputs.
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