TPS61176 Can't the PWM / EN pin directly input 1.8V or 5V DC with constant voltage? Use the circuit in the figure below to supply 5V DC power and provide 1.8V DC power to the PWM / EN pin. There is no output measured. Must the PWM / EN pin of this chip provide a square wave voltage signal greater than a certain frequency? If necessary, can you recommend a chip with adjustable frequency and duty cycle output, thank you! !! !!