UC3845D8TRG4

Power Supply Controllers, Monitors Overview

The UC3845D8TRG4 is a current-mode PWM controller manufactured by Texas Instruments, designed for high-performance DC-DC switching applications. It operates within an input voltage range of 10V to 30V and supports switching frequencies up to 500kHz. The device features a maximum duty cycle of 50% and includes integrated circuit protection mechanisms such as under-voltage lockout and overcurrent limiting. Packaged in an 8-SOIC surface-mount format, it functions across a temperature range of 0°C to 70°C.

Power Supply Controllers, Monitors Feature Summary

• Implements current-mode control architecture for rapid transient response and simplified loop compensation.
• Integrates precision oscillator with external timing resistor and capacitor for flexible frequency selection.
• Includes built-in under-voltage lockout with hysteresis to ensure stable startup and shutdown sequences.
• Features active low-current discharge pin to rapidly de-energize the external switch gate capacitance.

Power Supply Controllers, Monitors Applications

• Flyback converter designs for isolated power supplies
• Forward converter topologies requiring single-ended output
• Boost and Buck non-isolated DC-DC regulation circuits
• Battery charger controllers utilizing current-mode feedback

Power Supply Controllers, Monitors Procurement Notes

Verify the suffix G4 indicates lead-free composition compliant with RoHS standards. Confirm the D8 package designation matches the required 8-SOIC footprint and thermal characteristics. Ensure the ordering quantity aligns with the manufacturer's standard reel packaging specifications to avoid cut-tape handling fees or availability constraints during procurement.

Power Supply Controllers, Monitors Selection Notes

Select this component when designing converters requiring a fixed 50% maximum duty cycle limit. It is suitable for applications where current-mode control offers advantages over voltage-mode architectures. Consider the 8-pin SOIC package for space-constrained PCB layouts. Validate that the operating frequency requirements fall within the supported range defined by the external RC network.

Power Supply Controllers, Monitors Part Context

This part belongs to the UCx84x family of current-mode PWM controllers, sharing core functional blocks with variants like UC3842, UC3843, and UC3844. The primary distinction lies in the maximum duty cycle specification, which is limited to 50% for the UC3845 series compared to higher limits in other family members. This limitation ensures safe operation in specific transformer reset scenarios.

Power Supply Controllers, Monitors Replacement Considerations

Direct substitutes include UC3845DTR and UC3845AD8TRG4 from Texas Instruments, maintaining identical electrical performance and pinout compatibility. Cross-manufacturer equivalents may require verification of pin definitions and thermal parameters to ensure functional interchangeability without circuit modification.