Overview
Features and Benefits
- 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
Product Details
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
Product Categories
Markets and Technologies
Product Lifecycle
Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Documentation & Resources
-
R086 Reliability Data3/22/2018
-
AN67 - Linear Technology Magazine Circuit Collection, Volume III8/20/2007
-
AN60 - PCMCIA Card and Card Socket Power Management:8/20/2007
-
AN58 - 5V to 3.3V Converters for Microprocessor Systems8/20/2007
-
AN54 - Power Conversion from Milliamps to Amps at Ultra-High Efficiency (Up to 95%)8/20/2007
-
AN53 - Micropower High Side MOSFET Drivers8/20/2007
-
AN51 - Power Conditioning for Notebook and Palmtop Systems8/20/2007
-
AN-105: Current Sense Circuit Collection Making Sense of Current12/1/2005
-
DN96 - 12-Bit Rail-to-Rail Micropower DACs in an SO-87/8/2014
-
DN76 - PC Card Power Management Techniques4/1/2014
-
DN82 - 5V to 3.3V Regulator with Fail-Safe Switchover3/26/2014
-
DN210 - 2-Phase, Dual Switching Regulator Fits in Tight Places3/21/2014
-
DN78 - Triple Output 3.3V, 5V, and 12V High Efficiency Notebook Power Supply3/21/2014
-
DN91 - 5V to 3.3V Circuit Collection3/21/2014
-
Design Note 97: Flash Memory VPP Generator Reference Design2/1/1995
-
Design Note 74: Techniques for Deriving 3.3V from 5V Supplies9/1/1993
-
Three-Terminal Linear Regulator Evolution Continues Unabated2/19/2015
-
Wide Input Range, High Efficiency Step-Down Switching Regulators11/1/1998 LT Journal
Tools & Simulations
LTspice
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
LT1121
LT1121-3.3
LT1121-5
Design Resources
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.
PCN-PDN Information
Select a model from the dropdown below to subscribe to PCN/PDN notifications and view past notifications as well.
Support & Discussions
LT1121 Discussions
Sample & Buy
Ordering FAQs
See our Ordering FAQs for answers to questions about online orders, payment options and more.
Buy Now Pricing
(**) Displayed Buy Now Price and Price Range is based on small quantity orders.
List Pricing
(*)The 1Ku list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
Lead Times
Please see the latest communication from our CCO regarding lead times.
Sampling
A Sample link will be shown above, next to the part, only for parts that are included in our sample program. Selecting the Sample button will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.