Do all conventional buck converters with synchronous rectification self destruct if a voltage greater than regulated output voltage is applied to the output ?
For example an adjustable synchronous buck converter is used to charges a car battery. Everything works fine, until you adjust supply output lower than battery voltage. The duty cycle attempts to decreases to 0% because of feedback loop.
The low side MOSFET stays on and goes up in a a puff of smoke. Alternatively the duty cycle merely reduces, and you have an unregulated boost converter with the converters original input terminal voltage going sky high and similarly releasing smoke.
I confirmed this with a 3A synchronous buck converter based on integrated switch IC (AP6503), the converter input terminals shot to 40V soon as I applied above 10mv over the regulated output voltage.
What confuses me is there seems to be extremely little on the subject. With number of rechargeable batteries existing in the world and popularity of power supplies with synchronous rectification, there hasn't been anyone who has connected the two together.
Adam
For example an adjustable synchronous buck converter is used to charges a car battery. Everything works fine, until you adjust supply output lower than battery voltage. The duty cycle attempts to decreases to 0% because of feedback loop.
The low side MOSFET stays on and goes up in a a puff of smoke. Alternatively the duty cycle merely reduces, and you have an unregulated boost converter with the converters original input terminal voltage going sky high and similarly releasing smoke.
I confirmed this with a 3A synchronous buck converter based on integrated switch IC (AP6503), the converter input terminals shot to 40V soon as I applied above 10mv over the regulated output voltage.
What confuses me is there seems to be extremely little on the subject. With number of rechargeable batteries existing in the world and popularity of power supplies with synchronous rectification, there hasn't been anyone who has connected the two together.
Adam