SNVSB87 November 2018 LM3880-Q1
Connecting the EN pin to VCC is not recommended. During power up, the EN voltage should be kept below the EN threshold until VCC rises above the minimum operating voltage. This will be violated if EN is connected to VCC, and undefined operation at the flag outputs can occur, especially during slow VCC rising slew rates. For systems requiring only power-up sequencing, a capacitor at the EN pin can be used to create a delay or a resistor divider can be used to enable the device based on a certain voltage threshold. While these solutions will work for power-up, it will not power-down the flag outputs in sequential fashion since the flag outputs will simply follow the input supply. For systems requiring both power-up and power-down sequencing, an external enable signal should be used, such as a GPIO signal from a microcontroller, to properly control power-up and power-down of the flag outputs.