LT1123CZ#PBF

Overview

The LT1123CZ#PBF is a low dropout regulator driver designed for use with discrete PNP power transistors to create cost-effective regulators. It features a fixed 5V output trimmed to ±1% and operates within a junction temperature range of 0°C to 125°C. The device provides a quiescent current of 700µA, line regulation of 1mV, and load regulation of 5mV. It can sink up to 125mA of drive current to support output currents up to 4A. The component is housed in a 3-lead TO-92 plastic package.

Feature Summary

• Incorporates a trimmed bandgap reference and error amplifier for precise voltage control
• Includes internal thermal limiting and current foldback protection mechanisms
• Features a drive pin capable of sinking significant base current for external pass transistors

Applications

• Ultralow dropout linear regulator circuits using discrete PNP transistors
• Battery backup systems requiring stable 5V outputs
• Lead-acid battery charging and regulation applications

Procurement Notes

Verify the specific suffix CZ#PBF corresponds to the TO-92 package variant when sourcing. Confirm that the intended application utilizes an external PNP transistor, as this component functions strictly as a driver rather than a complete standalone regulator. Ensure thermal management strategies account for the device's operating temperature limits.

Selection Notes

Select this component when designing inexpensive regulators requiring a fixed 5V output. It is suitable for applications needing high drive capability to support large external transistors. Consider the thermal resistance characteristics of the TO-92 package during layout planning to ensure operation remains within safe junction temperature limits under worst-case dissipation conditions.

Part Context

This part belongs to the LT1123 family of low dropout regulator drivers manufactured by Analog Devices Inc. It serves as a control element that must be paired with external components, specifically a PNP power transistor, to function as a complete voltage regulation solution. The device simplifies regulator design by integrating reference and amplification stages.

Replacement Considerations

LT1123CST#PBF (SOT-223 package equivalent)