UC3845BN

DC DC Switching Controllers Overview

The UC3845BN is a high-performance current mode PWM controller from onsemi, designed for offline and DC-DC converter applications. It operates with a maximum switching frequency of 275 kHz and provides a peak output current of 1 A. The device supports Boost and Flyback topologies with a maximum duty cycle of 50%. It functions within an operating supply voltage range of 12 V to 25 V and maintains operation between -40 °C and +70 °C. The component is housed in an 8-pin PDIP package.

DC DC Switching Controllers Feature Summary

• Implements fixed-frequency current mode control schemes with minimal external components
• Features an internally trimmed oscillator for precise frequency control and duty cycle regulation
• Includes a precision reference and high-gain error amplifier for accurate feedback processing
• Provides a high-current totem pole output stage suitable for driving N-Channel MOSFETs

DC DC Switching Controllers Applications

• Offline power supplies
• DC-to-DC converters
• Battery chargers

DC DC Switching Controllers Procurement Notes

Verify the specific suffix 'BN' against the manufacturer's official datasheet to confirm the PDIP-8 package and commercial temperature grade. Ensure the ordering part number matches the exact electrical specifications required for the design, as variations exist within the UC384xB family regarding UVLO thresholds and duty cycle limits.

DC DC Switching Controllers Selection Notes

Select this component when a 50% maximum duty cycle is required for flyback or boost topologies. It is suitable for designs needing current mode control with a switching frequency up to 275 kHz. Consider the through-hole PDIP-8 package if board space allows and manual assembly or robust mounting is preferred over surface mount alternatives.

DC DC Switching Controllers Part Context

The UC3845BN belongs to the UC284xB series of current mode controllers. This family shares core architectures but differs in under-voltage lockout thresholds and duty cycle capabilities. While other members like the UC2842B approach 100% duty cycles, the UC3845B utilizes an internal toggle flip-flop to limit the duty cycle to less than 50%, making it distinct for specific transformer reset requirements.

DC DC Switching Controllers Replacement Considerations

Compatible substitutes include UC3845BD1G, UC3845BVNG, and UC3845BVD1R2G. Verify that replacement parts maintain the same 50% duty cycle limit and compatible pinout configuration before integration.