themaccabee
Full Member level 4
Hi,
Can somebody tell me how to properly design a startup resistor value for a UC3845 IC.
My objective is to test the IC oscillator section with 24V supply input.
I just connected the Vcc pin to 24V power supply through a 6kOhm 1/2W resistor. The IC isnt starting and the Vcc Pin is showing around 8V.(As per datasheet the maximum value of threshold minimum turn on voltage can go upto around 9V)
I vary the Supply voltage to around 35V then the IC gets into oscillation mode like say the reference voltage of 5V is getting ON and OFF continuously.
What circuitry is exactly inside the Vcc pin in the IC that controls the startup behaviour??
Like if in know a equivalent internal circuit my understanding will be better..
Thanks for any help
Can somebody tell me how to properly design a startup resistor value for a UC3845 IC.
My objective is to test the IC oscillator section with 24V supply input.
I just connected the Vcc pin to 24V power supply through a 6kOhm 1/2W resistor. The IC isnt starting and the Vcc Pin is showing around 8V.(As per datasheet the maximum value of threshold minimum turn on voltage can go upto around 9V)
I vary the Supply voltage to around 35V then the IC gets into oscillation mode like say the reference voltage of 5V is getting ON and OFF continuously.
What circuitry is exactly inside the Vcc pin in the IC that controls the startup behaviour??
Like if in know a equivalent internal circuit my understanding will be better..
Thanks for any help