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2022-09-24 23:33:15
UCX823A - High Speed PWM Controller
UC3823A & B and UC3825A PWM control ICs and B family improved versions of the standard UC3823 and UC3825 series. Performance enhancements have been made to several circuit blocks. The error amplifier gain-bandwidth product is 12MHz, and the input offset voltage is 2mV. The current limit threshold is guaranteed to a 5% tolerance. The discharge current of the oscillator is controlled at 10mA with a specified precise dead time. Frequency accuracy improved to 6%. Startup supply current, typically 100mA, ideal for off-line applications. The output driver has been redesigned to actively receive current during UVLO, at no expense of startup current specification. Additionally, each output is capable of 2A peak current during conversion. Functional improvements have also been implemented in this family. The UC3825 shutdown comparator is now a high-speed overcurrent comparator with a 1.2V threshold. The overcurrent comparator sets a latch to ensure that the all-rounder discharges the soft-start capacitor to allow restarts. Although the fault latch is set, the output is in the low state. In the case of continuous faults, the soft-start capacitor is fully charged before discharging to ensure that the frequency of faults does not exceed the designed soft-start period. The UC3825 clock pin has become CLK/LEB. This pin integrates the clock output function and leading edge blanking adjustment and makes it easier to connect buffers.