UC3825B - 高速 PWM 控制器

UC3825B是TI德州仪器公司的一款PWM与谐振控制器产品，UC3825B是高速 PWM 控制器，本站介绍了UC3825B的封装应用图解、特点和优点、功能等，并给出了与UC3825B相关的TI元器件型号供参考。

UC3825B - 高速 PWM 控制器 - PWM与谐振控制器 - 离线隔离型DC/DC控制器和转换器 - 德州仪器

产品描述

The UC3823A and UC3823B and the UC3825A and UC3825B family of PWM controllers are improved versions of the standard UC3823 and UC3825 family. Performance enhancements have been made to several of the circuit blocks. Error amplifier gain bandwidth product is 12 MHz, while input offset voltage is 2 mV. Current limit threshold is assured to a tolerance of 5%. Oscillator discharge current is specified at 10 mA for accurate dead time control. Frequency accuracy is improved to 6%. Startup supply current, typically 100 µA, is ideal for off-line applications. The output drivers are redesigned to actively sink current during UVLO at no expense to the startup current specification. In addition each output is capable of 2-A peak currents during transitions.

Functional improvements have also been implemented in this family. The UC3825 shutdown comparator is now a high-speed overcurrent comparator with a threshold of 1.2 V. The overcurrent comparator sets a latch that ensures full discharge of the soft-start capacitor before allowing a restart. While the fault latch is set, the outputs are in the low state. In the event of continuous faults, the soft-start capacitor is fully charged before discharge to insure that the fault frequency does not exceed the designed soft start period. The UC3825 CLOCK pin has become CLK/LEB. This pin combines the functions of clock output and leading edge blanking adjustment and has been buffered for easier interfacing.

The UC3825A and UC3825B have dual alternating outputs and the same pin configuration of the UC3825. The UC3823A and UC3823B outputs operate in phase with duty cycles from zero to less than 100%. The pin configuration of the UC3823A and UC3823B is the same as the UC3823 except pin 11 is now an output pin instead of the reference pin to the current limit comparator. "A" version parts have UVLO thresholds identical to the original UC3823 and UC3825. The "B" versions have UVLO thresholds of 16 V and 10 V, intended for ease of use in off-line applications.

Consult the application note, The UC3823A,B and UC3825A,B Enhanced Generation of PWM Controllers, (SLUA125) for detailed technical and applications information.

产品特性

Improved Versions of the UC3823/UC3825 PWMs
Compatible with Voltage-Mode or Current-Mode Control Methods
Practical Operation at Switching Frequencies to 1 MHz
50-ns Propagation Delay to Output
High-Current Dual Totem Pole Outputs (2-A Peak)
Trimmed Oscillator Discharge Current
Low 100-µA Startup Current
Pulse-by-Pulse Current Limiting Comparator
Latched Overcurrent Comparator With Full Cycle Restart

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