TI UC3823BDW

The UC3823A, UC3823B, UC3825A, and UC3825B series of PWM controllers are improved versions of the standard UC3823 and UC3825 series, with enhanced performance in several circuit blocks. The error amplifier has a gain-bandwidth product of 12 MHz and an input offset voltage of 2 mV. The current limit threshold is verified to be within 5% tolerance. To achieve precise dead-time control, the oscillator discharge current rating is 10 mA. The frequency accuracy is improved to 6%. The start-up supply current, with a typical value of 100 μA, is well-suited for offline applications. The output driver is redesigned to actively sink current during UVLO without affecting the start-up current specification. Additionally, each output can deliver a peak current of 2 A during transitions. Functional improvements are also implemented in this series. The UC3825 shutdown comparator is now a high-speed overcurrent comparator with a threshold of 1.2 V. This overcurrent comparator ensures that the soft-start capacitor is fully discharged before allowing a restart by setting the latch. When the fault latch is set, the output is low. In case of a persistent fault, the soft-start capacitor is charged before discharging to ensure that the fault frequency does not exceed the designed soft-start period. The UC3825 clock pin has become CLK/LEB. This pin combines the clock output and leading-edge blanking adjustment functions, providing a buffered output for easy connection. The UC3825A and UC3825B feature dual alternating outputs and the same pin configuration as the UC3825. The UC3823A and UC3823B outputs operate in phase, with a duty cycle ranging from 0 to less than 100%. The pin configuration of the UC3823A and UC3823B is the same as that of the UC3823 (except for pin 11, which is now an output pin instead of the reference pin for the current limit comparator). Version A devices have the same UVLO thresholds as the original UC3823 and UC3825. Version B has UVLO thresholds of 16 V and 10 V, which are convenient for offline applications.

• Improved version of UC3823/UC3825 PWM controllers
• Compatible with voltage-mode or current-mode control methods
• Switching frequency up to 1MHz
• 50ns propagation delay to output
• High-current dual totem-pole outputs (2A peak)
• Trimmed oscillator discharge current
• Low 100μA startup current
• Pulse-by-pulse current limiting comparator
• Latched overcurrent comparator with full-cycle restart capability