UC3833DWTR

Overview

The UC3833DWTR is a precision low dropout linear controller manufactured by Texas Instruments, designed for use with external pass transistors to create highly efficient voltage regulators. It operates within an input supply range of 4.5 V to 36 V and features a precise 2 V reference with a tolerance of ±1%. The device includes an error amplifier, under-voltage lockout (UVLO), and a high-current driver capable of sourcing or sinking up to 100 mA. It utilizes a duty-ratio current limiting technique that allows peak load capability while protecting the external pass transistor during fault conditions. The component is housed in a 16-pin SOIC package.

Feature Summary

• Innovative duty-ratio current limiting technique provides peak load capability while limiting average power dissipation of the external pass transistor during faults.
• Includes a precision 2 V reference and an error amplifier for accurate regulation.
• Features a high-current driver with both source and sink outputs, allowing compatibility with either NPN or PNP external pass transistors.
• Ensures safe operation through integrated under-voltage lockout (UVLO) and thermal shutdown protection.

Applications

• Designing very low dropout linear regulators using external NPN or PNP pass transistors.
• Power supply systems requiring adjustable current limit and programmable duty-ratio over-current protection.
• Applications needing high initial load demands and short circuit protection without extra heat sinking or foldback current limiting.

Procurement Notes

Verify the specific ordering suffix to confirm the tape and reel packaging format, as the 'DWTR' designation indicates surface mount delivery. Ensure the selected variant matches the required operating temperature range, as commercial versions are specified for 0°C to 70°C. Confirm RoHS compliance status and moisture sensitivity level ratings prior to assembly planning. Cross-reference the manufacturer part number with official distributor catalogs to ensure authenticity and traceability.

Selection Notes

Select this controller when designing custom low dropout regulators that require precise current limiting and high efficiency. It is suitable for applications where the output voltage needs to be set via external components rather than being fixed internally. Consider the external pass transistor requirements based on the driver's source and sink capabilities. Evaluate the thermal management needs for the external pass element, as the controller limits average power dissipation but does not regulate the pass transistor's thermal performance directly.

Part Context

The UC3833 is part of the UCx832/UCx833 family of precision low dropout linear controllers from Texas Instruments. While the UC2832 series offers additional versatility with more pins and features like a separate +VIN terminal and logic-level disable, the UC3833 provides the core control functions in a simplified configuration. This family is designed to replace traditional fixed-output regulators by allowing designers to customize the output voltage and current limits using external components.

Replacement Considerations

• UC3833DW
• UC2833DW

FAQ

How does the UC3833 handle short circuit conditions?

The UC3833 uses a gated-astable timer enabled when the load current reaches a programmed threshold. This switches the regulator’s pass device off and on at an externally programmable duty-ratio, accommodating short circuit protection without requiring extra heat sinking or foldback current limiting.

Can the UC3833 drive both NPN and PNP transistors?

Yes, the IC includes a high current driver that has both source and sink outputs. This design flexibility allows the use of either NPN or PNP external pass transistors depending on the specific regulator topology required.