KA3843BD

AC DC Converters, Offline Switchers Overview

The KA3843BD is a fixed-frequency current-mode PWM controller manufactured by Fairchild Semiconductor. It utilizes BICMOS technology and operates within an industrial temperature range of -40 °C to 70 °C. The device features a maximum switching frequency of 55 kHz and provides a maximum output current of 1 A. It is housed in a 14-pin SOP package (PDSO14). The controller includes a trimmed oscillator, temperature-compensated reference, high-gain error amplifier, current sensing comparator, and a high-current totetpole output designed for driving power MOSFETs.

AC DC Converters, Offline Switchers Feature Summary

• Implements current-mode control architecture for precise duty cycle regulation
• Integrates a high-current totetpole output stage optimized for direct MOSFET driving
• Includes internal temperature-compensated voltage reference and high-gain error amplifier

AC DC Converters, Offline Switchers Applications

• Offline switch-mode power supply designs
• DC-to-DC converter circuits
• General-purpose SMPS controller applications

AC DC Converters, Offline Switchers Procurement Notes

Verify the specific manufacturer source, as ON Semiconductor also lists this part number. Confirm RoHS compliance status, as database records indicate non-compliance for some variants while others may differ. Ensure the 14-pin SOP package matches the design requirements. Validate that the 70 °C maximum operating temperature meets the thermal constraints of the target application environment.

AC DC Converters, Offline Switchers Selection Notes

Select this component for applications requiring fixed-frequency current-mode control with minimal external components. The 1 A output capability supports direct drive of power MOSFETs without additional buffering. Consider the 55 kHz switching frequency for standard transformer and inductor sizing. Verify compatibility with the required input voltage range of 11.5 V to 30 V for the specific circuit topology.

AC DC Converters, Offline Switchers Part Context

The KA3843BD belongs to the KA3842B/KA3843B/KA3844B/KA3845B family of fixed-frequency current-mode PWM controllers. These devices are engineered for offline and DC-to-DC converters, offering integrated features such as a trimmed oscillator and high-gain error amplifier to minimize external component count. The family shares similar control architectures but varies in pinout and specific electrical characteristics.

AC DC Converters, Offline Switchers Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation.