The UCC3570N is a Pulse Width Modulation (PWM) Controller intended for application in isolated switching supplies using primary side control and a voltage mode feedback loop. Made with a BiCMOS process, these devices feature low startup current for efficient off-line starting with a bootstrapped low voltage supply. Operating current is also very low; yet these devices maintain the ability to drive a power MOSFET gate at frequencies above 500kHz. Voltage feed forward provides fast and accurate response to wide line voltage variation without the noise sensitivity of current-mode control. Fast current limiting is included with the ability to latch off after a programmable number of repetitive faults have occurred. This allows the power supply to ride through a temporary overload, while still shutting down in the event of a permanent fault.
