UCC2837D

Overview

The UCC2837D is an 8-pin N-FET linear regulator controller manufactured by Texas Instruments. It operates from input voltages as low as 3V and supports output voltages down to 1.5V. The device features a built-in charge pump for external N-MOSFET gate drive, duty ratio mode overcurrent protection, and extremely low dropout voltage characteristics. Electrical specifications include a supply current of 1.5mA at VDD=5V, a reference voltage of 1.5V, and a comparator offset of 100mV. It functions within a temperature range of -25°C to +85°C and is housed in an SOIC-8 package.

Feature Summary

• Integrates an onboard charge pump to generate the necessary gate drive voltage for external N-channel MOSFETs, enabling high efficiency and low dropout performance.
• Employs a duty ratio mode overcurrent protection technique that limits average power dissipation during fault conditions while maintaining peak transient loading capability.
• Provides adjustable output voltage settings starting from 1.5V, allowing optimization for custom processor voltages and logic levels beyond standard three-terminal regulator ranges.

Applications

• Custom processor voltage regulation
• Bus termination voltage generation
• Logic level voltage supplies below 3V

Procurement Notes

Verify the specific ordering suffix (e.g., D) against the official TI datasheet to confirm the package type and operating temperature range. Ensure the selected variant matches the required industrial or commercial grade specifications. Cross-reference the manufacturer part number with authorized distributors to validate authenticity and traceability before finalizing procurement orders.

Selection Notes

Select this component when designing linear regulators requiring extremely low dropout voltages and high efficiency using external N-MOSFET pass elements. Consider the internal charge pump limitations and ensure adequate capacitance on the CAP pin for stable gate drive. Evaluate the duty cycle timer capacitor requirements to properly configure overcurrent protection thresholds for the specific load conditions.

Part Context

The UCC2837D belongs to the UCC3837 family of linear regulator controllers, which also includes the UCC1837 and UCC3837 variants differentiated primarily by their operating temperature ranges. This series is designed to replace standard three-terminal regulators where lower dropout and higher current capabilities are required. It utilizes a transconductance error amplifier and current sense amplifier for precise loop control.

Replacement Considerations

Direct replacements within the same family include the UCC1837 and UCC3837, provided the extended or commercial temperature ranges align with system requirements. Verify pin compatibility and electrical parameters such as reference voltage and current limits when substituting.

FAQ

How does the UCC2837D handle overcurrent protection?

It uses a duty ratio mode overcurrent protection technique. If the voltage across the current sense resistor exceeds the threshold, the device modulates the output driver at a specific duty cycle to limit average power dissipation during faults.

What is the function of the CAP pin?

The CAP pin is the output of the internal charge pump circuit. It provides a floating bias voltage to drive the gate of the external N-channel MOSFET pass transistor. A minimum 0.01 µF ceramic capacitor is recommended between this pin and ground.