LT1121

PRODUCTION

Micropower Low Dropout Regulators with Shutdown

Part Models: 54
1ku List Price: Starting From $2.00

Viewing:

Overview

0.4V Dropout Voltage
150mA Output Current
30µA Quiescent Current
No Protection Diodes Needed
Adjustable Output from 3.75V to 30V
3.3V and 5V Fixed Output Voltages
Controlled Quiescent Current in Dropout
Shutdown
16µA Quiescent Current in Shutdown
Stable with 0.33µF Output Capacitor
Reverse Battery Protection
No Reverse Current with Input Low
Thermal Limiting
Available in the 8-Lead SO, 8-Lead PDIP, 3-Lead SOT-23 and 3-Lead TO-92 Packages

The LT1121/LT1121-3.3/LT1121-5 are micropower low dropout regulators with shutdown. These devices are capable of supplying 150mA of output current with a dropout voltage of 0.4V. Designed for use in battery-powered systems, the low quiescent current, 30µA operating and 16µA in shutdown, makes them an ideal choice. The quiescent current is well-controlled; it does not rise in dropout as it does with many other low dropout PNP regulators.

Other features of the LT1121/LT1121-3.3/LT1121-5 include the ability to operate with very small output capacitors. They are stable with only 0.33µF on the output while most older devices require between 1µF and 100µF for stability. Small ceramic capacitors can be used, enhancing manufacturability. Also the input may be connected to ground or a reverse voltage without reverse current flow from output to input. This makes the LT1121 series ideal for backup power situations where the output is held high and the input is at ground or reversed. Under these conditions only 16µA will flow from the output pin to ground.

Applications

Low Current Regulator
Regulator for Battery-Powered Systems
Post Regulator for Switching Supplies

Part Models: 54
1ku List Price: Starting From $2.00

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT1121ACS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121ACS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121ACS8-3.3#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121ACS8-3.3#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121ACS8-5#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121ACS8-5#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AHVCS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AHVCS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AHVIS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AHVIS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AIS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AIS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AIS8-3.3#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AIS8-3.3#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AIS8-5#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121AIS8-5#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CN8#PBF	8-Lead PDIP (Narrow 0.3 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CN8-3.3#PBF	8-Lead PDIP (Narrow 0.3 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CN8-5#PBF	8-Lead PDIP (Narrow 0.3 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CS8-3.3#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CS8-3.3#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CS8-5#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CS8-5#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CST-3.3#PBF	3-Lead SOT-223	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CST-3.3#TRPBF	3-Lead SOT-223	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CST-5#PBF	3-Lead SOT-223	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CST-5#TRPBF	3-Lead SOT-223	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CZ-3.3#PBF	3-Lead TO-92	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CZ-3.3#TRPBF	3-Lead TO-92	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CZ-5#PBF	3-Lead TO-92	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121CZ-5#TRPBF	3-Lead TO-92	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121HVCS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121HVCS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121HVIS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121HVIS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IN8#PBF	8-Lead PDIP (Narrow 0.3 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IN8-3.3#PBF	8-Lead PDIP (Narrow 0.3 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IN8-5#PBF	8-Lead PDIP (Narrow 0.3 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IS8-3.3#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IS8-3.3#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IS8-5#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IS8-5#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IST-3.3#PBF	3-Lead SOT-223	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IST-3.3#TRPBF	3-Lead SOT-223	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IST-5#PBF	3-Lead SOT-223	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IST-5#TRPBF	3-Lead SOT-223	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IZ-3.3#PBF	3-Lead TO-92	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IZ-3.3#TRPBF	3-Lead TO-92	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IZ-5#PBF	3-Lead TO-92	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1121IZ-5#TRPBF	3-Lead TO-92	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Oct 8, 2024 - 24_0236 Migrating Bottom Trace Code Marking to Top Side Laser Marking for SOIC_N Package
		PCN24_0236_Form Material_Report Marking Comparison Delta Qualification Matrix
LT1121ACS8#PBF	PRODUCTION
LT1121ACS8#TRPBF	PRODUCTION
LT1121ACS8-3.3#PBF	PRODUCTION
LT1121ACS8-3.3#TRPBF	PRODUCTION
LT1121ACS8-5#PBF	PRODUCTION
LT1121ACS8-5#TRPBF	PRODUCTION
LT1121AHVCS8#PBF	PRODUCTION
LT1121AHVCS8#TRPBF	PRODUCTION
LT1121AHVIS8#PBF	PRODUCTION
LT1121AHVIS8#TRPBF	PRODUCTION
LT1121AIS8#PBF	PRODUCTION
LT1121AIS8#TRPBF	PRODUCTION
LT1121AIS8-3.3#PBF	PRODUCTION
LT1121AIS8-3.3#TRPBF	PRODUCTION
LT1121AIS8-5#PBF	PRODUCTION
LT1121AIS8-5#TRPBF	PRODUCTION
LT1121CS8#PBF	PRODUCTION
LT1121CS8#TRPBF	PRODUCTION
LT1121CS8-3.3#PBF	PRODUCTION
LT1121CS8-3.3#TRPBF	PRODUCTION
LT1121CS8-5#PBF	PRODUCTION
LT1121CS8-5#TRPBF	PRODUCTION
LT1121IS8#PBF	PRODUCTION
LT1121IS8#TRPBF	PRODUCTION
LT1121IS8-3.3#PBF	PRODUCTION
LT1121IS8-3.3#TRPBF	PRODUCTION
LT1121IS8-5#PBF	PRODUCTION
LT1121IS8-5#TRPBF	PRODUCTION
Oct 12, 2022 - 22_0254 Epoxy Change from Henkel 8290 to 8290A for 8-Lead SOIC Package (PCN part 1 of 2)
		PCN22_0254_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LT1121ACS8#PBF	PRODUCTION
LT1121ACS8#TRPBF	PRODUCTION
LT1121ACS8-3.3#PBF	PRODUCTION
LT1121ACS8-3.3#TRPBF	PRODUCTION
LT1121ACS8-5#PBF	PRODUCTION
LT1121ACS8-5#TRPBF	PRODUCTION
LT1121AHVCS8#PBF	PRODUCTION
LT1121AHVCS8#TRPBF	PRODUCTION
LT1121AHVIS8#PBF	PRODUCTION
LT1121AHVIS8#TRPBF	PRODUCTION
LT1121AIS8#PBF	PRODUCTION
LT1121AIS8#TRPBF	PRODUCTION
LT1121AIS8-3.3#PBF	PRODUCTION
LT1121AIS8-3.3#TRPBF	PRODUCTION
LT1121AIS8-5#PBF	PRODUCTION
LT1121AIS8-5#TRPBF	PRODUCTION
LT1121CS8-3.3#PBF	PRODUCTION
LT1121CS8-3.3#TRPBF	PRODUCTION
Jun 11, 2021 - 21_0060 Laser Top Mark for 8SOICN Assembled in ADPG, UTL and CRM
		PCN21_0060_Form Material_Report Delta Qualification Matrix
LT1121ACS8#PBF	PRODUCTION
LT1121ACS8#TRPBF	PRODUCTION
LT1121ACS8-3.3#PBF	PRODUCTION
LT1121ACS8-3.3#TRPBF	PRODUCTION
LT1121ACS8-5#PBF	PRODUCTION
LT1121ACS8-5#TRPBF	PRODUCTION
LT1121AHVCS8#PBF	PRODUCTION
LT1121AHVCS8#TRPBF	PRODUCTION
LT1121AHVIS8#PBF	PRODUCTION
LT1121AHVIS8#TRPBF	PRODUCTION
LT1121AIS8#PBF	PRODUCTION
LT1121AIS8#TRPBF	PRODUCTION
LT1121AIS8-3.3#PBF	PRODUCTION
LT1121AIS8-3.3#TRPBF	PRODUCTION
LT1121AIS8-5#PBF	PRODUCTION
LT1121AIS8-5#TRPBF	PRODUCTION
LT1121CS8#PBF	PRODUCTION
LT1121CS8#TRPBF	PRODUCTION
LT1121CS8-3.3#PBF	PRODUCTION
LT1121CS8-3.3#TRPBF	PRODUCTION
LT1121CS8-5#PBF	PRODUCTION
LT1121CS8-5#TRPBF	PRODUCTION
LT1121HVCS8#PBF	PRODUCTION
LT1121HVCS8#TRPBF	PRODUCTION
LT1121HVIS8#PBF	PRODUCTION
LT1121HVIS8#TRPBF	PRODUCTION
LT1121IS8#PBF	PRODUCTION
LT1121IS8#TRPBF	PRODUCTION
LT1121IS8-3.3#PBF	PRODUCTION
LT1121IS8-3.3#TRPBF	PRODUCTION
LT1121IS8-5#PBF	PRODUCTION
LT1121IS8-5#TRPBF	PRODUCTION
Oct 8, 2024 - 24_0234 Migrating Bottom Trace Code Marking to Top Side Laser Marking for PDIP Package
		PCN24_0234_Form Material_Report Marking Comparison
LT1121CN8#PBF	PRODUCTION
LT1121CN8-3.3#PBF	PRODUCTION
LT1121CN8-5#PBF	PRODUCTION
LT1121IN8#PBF	PRODUCTION
LT1121IN8-3.3#PBF	PRODUCTION
LT1121IN8-5#PBF	PRODUCTION
Oct 11, 2022 - 22_0241 Epoxy Change from Henkel 8290 to 8290A for PDIP Package
		PCN22_0241_Form Material_Report Qualification Results Summary
LT1121CN8#PBF	PRODUCTION
LT1121CN8-3.3#PBF	PRODUCTION
LT1121CN8-5#PBF	PRODUCTION
LT1121IN8#PBF	PRODUCTION
LT1121IN8-3.3#PBF	PRODUCTION
LT1121IN8-5#PBF	PRODUCTION
Aug 6, 2022 - 22_0172 Laser Top Mark Conversion for PDIP Packages Assembled in ADPG [PNG]
		PCN22_0172_Form Material_Report Delta Qualification Matrix
LT1121CN8#PBF	PRODUCTION
LT1121CN8-3.3#PBF	PRODUCTION
LT1121CN8-5#PBF	PRODUCTION
LT1121IN8#PBF	PRODUCTION
LT1121IN8-3.3#PBF	PRODUCTION
LT1121IN8-5#PBF	PRODUCTION
Nov 14, 2022 - 22_0254 Epoxy Change from Henkel 8290 to 8290A for 8-Lead SOIC Package (PCN part 1 of 2)
		PCN22_0254_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LT1121CS8#PBF	PRODUCTION
LT1121CS8#TRPBF	PRODUCTION
LT1121IS8#PBF	PRODUCTION
LT1121IS8#TRPBF	PRODUCTION
Dec 14, 2023 - 22_0255 Epoxy Change from Henkel 8290 to 8290A for 8-Lead SOIC Package (PCN part 2 of 2)
		PCN22_0255_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LT1121CS8-5#PBF	PRODUCTION
LT1121CS8-5#TRPBF	PRODUCTION
LT1121HVCS8#PBF	PRODUCTION
LT1121HVCS8#TRPBF	PRODUCTION
LT1121HVIS8#PBF	PRODUCTION
LT1121HVIS8#TRPBF	PRODUCTION
LT1121IS8-3.3#PBF	PRODUCTION
LT1121IS8-3.3#TRPBF	PRODUCTION
LT1121IS8-5#PBF	PRODUCTION
LT1121IS8-5#TRPBF	PRODUCTION
Feb 20, 2022 - 22_0014 Final Packaging Changes for TO-92, TO-5 and TO-46
		PCN22_0014_Form Material_Report Other
LT1121IZ-3.3#PBF	PRODUCTION
LT1121IZ-5#PBF	PRODUCTION
Mar 6, 2022 - 22_0014 Final Packaging Changes for TO-92, TO-5 and TO-46
		PCN22_0014_Form Material_Report Other
LT1121IZ-3.3#TRPBF	PRODUCTION
LT1121IZ-5#TRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Software Resources

Can't find the software or driver you need?

Request a Driver/Software

Hardware Ecosystem

Parts	Product Life Cycle	Description
LT1762	RECOMMENDED FOR NEW DESIGNS	150mA, Low Noise, LDO Micropower Regulators
LT3082	RECOMMENDED FOR NEW DESIGNS	200mA Single Resistor Low Dropout Linear Regulator

Tools & Simulations

LTspice 1

LT1121-3.3 Demo Circuit - 5V Battery-Powered Supply with Shutdown (3.7-20V to 3.3 @ 150mA)

Models for the following parts are available in LTspice:

LT1121
LT1121-3.3
LT1121-5

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

Latest Discussions

1 Years Ago

Overview

Documentation

Data Sheet 1

Reliability Data 1

Application Note 7

Design Note 10

Technical Articles 2