LT1121 - Micropower Low Dropout Regulators with Shutdown
Features
- 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
Typical Application
Description
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.
Packaging
For complete and up to date package information and drawings, please refer to our packaging page
SOT-223, SO-8, Z
Order Info
- Part numbers ending in PBF are lead free. Please contact LTC marketing for information on lead based finish parts.
- Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
- Please refer to our general ordering information or the product datasheet for more details
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) | Price (1k)* | RoHS Data |
|---|---|---|---|---|---|---|
| LT1121ACS8 | SO | 8 | C | $2.50 | $1.95 | View |
| LT1121ACS8#PBF | SO | 8 | C | $2.50 | $1.95 | View |
| LT1121ACS8#TR | SO | 8 | C | $2.01 | View | |
| LT1121ACS8#TRPBF | SO | 8 | C | $2.01 | View | |
| LT1121ACS8-3.3 | SO | 8 | C | $2.50 | $1.95 | View |
| LT1121ACS8-3.3#PBF | SO | 8 | C | $2.50 | $1.95 | View |
| LT1121ACS8-3.3#TR | SO | 8 | C | $2.01 | View | |
| LT1121ACS8-3.3#TRPBF | SO | 8 | C | $2.01 | View | |
| LT1121ACS8-5 | SO | 8 | C | $2.50 | $1.95 | View |
| LT1121ACS8-5#PBF | SO | 8 | C | $2.50 | $1.95 | View |
| LT1121ACS8-5#TR | SO | 8 | C | $2.01 | View | |
| LT1121ACS8-5#TRPBF | SO | 8 | C | $2.01 | View | |
| LT1121AHVCS8 | SO | 8 | C | $2.78 | $2.35 | View |
| LT1121AHVCS8#PBF | SO | 8 | C | $2.78 | $2.35 | View |
| LT1121AHVCS8#TR | SO | 8 | C | $2.42 | View | |
| LT1121AHVCS8#TRPBF | SO | 8 | C | $2.42 | View | |
| LT1121AHVIS8 | SO | 8 | I | $3.26 | $2.75 | View |
| LT1121AHVIS8#PBF | SO | 8 | I | $3.26 | $2.75 | View |
| LT1121AHVIS8#TR | SO | 8 | I | $2.81 | View | |
| LT1121AHVIS8#TRPBF | SO | 8 | I | $2.81 | View | |
| LT1121AIS8 | SO | 8 | I | $2.92 | $2.30 | View |
| LT1121AIS8#PBF | SO | 8 | I | $2.92 | $2.30 | View |
| LT1121AIS8#TR | SO | 8 | I | $2.36 | View | |
| LT1121AIS8#TRPBF | SO | 8 | I | $2.36 | View | |
| LT1121AIS8-3.3 | SO | 8 | I | $2.92 | $2.30 | View |
| LT1121AIS8-3.3#PBF | SO | 8 | I | $2.92 | $2.30 | View |
| LT1121AIS8-3.3#TR | SO | 8 | I | $2.36 | View | |
| LT1121AIS8-3.3#TRPBF | SO | 8 | I | $2.36 | View | |
| LT1121AIS8-5 | SO | 8 | I | $2.92 | $2.30 | View |
| LT1121AIS8-5#PBF | SO | 8 | I | $2.92 | $2.30 | View |
| LT1121AIS8-5#TR | SO | 8 | I | $2.36 | View | |
| LT1121AIS8-5#TRPBF | SO | 8 | I | $2.36 | View | |
| LT1121CN8 | PDIP | 8 | C | $1.83 | $1.50 | View |
| LT1121CN8#PBF | PDIP | 8 | C | $1.83 | $1.50 | View |
| LT1121CN8-3.3 | PDIP | 8 | C | $1.83 | $1.50 | View |
| LT1121CN8-3.3#PBF | PDIP | 8 | C | $1.83 | $1.50 | View |
| LT1121CN8-5 | PDIP | 8 | C | $1.83 | $1.50 | View |
| LT1121CN8-5#PBF | PDIP | 8 | C | $1.83 | $1.50 | View |
| LT1121CS8 | SO | 8 | C | $2.00 | $1.60 | View |
| LT1121CS8#PBF | SO | 8 | C | $2.00 | $1.60 | View |
| LT1121CS8#TR | SO | 8 | C | $1.66 | View | |
| LT1121CS8#TRPBF | SO | 8 | C | $1.66 | View | |
| LT1121CS8-3.3 | SO | 8 | C | $2.00 | $1.60 | View |
| LT1121CS8-3.3#PBF | SO | 8 | C | $2.00 | $1.60 | View |
| LT1121CS8-3.3#TR | SO | 8 | C | $1.66 | View | |
| LT1121CS8-3.3#TRPBF | SO | 8 | C | $1.66 | View | |
| LT1121CS8-5 | SO | 8 | C | $2.00 | $1.60 | View |
| LT1121CS8-5#PBF | SO | 8 | C | $2.00 | $1.60 | View |
| LT1121CS8-5#TR | SO | 8 | C | $1.66 | View | |
| LT1121CS8-5#TRPBF | SO | 8 | C | $1.66 | View | |
| LT1121CST-3.3 | SOT | 3 | C | $2.17 | $1.70 | View |
| LT1121CST-3.3#PBF | SOT | 3 | C | $2.17 | $1.70 | View |
| LT1121CST-3.3#TR | SOT | 3 | C | $1.76 | View | |
| LT1121CST-3.3#TRPBF | SOT | 3 | C | $1.76 | View | |
| LT1121CST-5 | SOT | 3 | C | $2.17 | $1.70 | View |
| LT1121CST-5#PBF | SOT | 3 | C | $2.17 | $1.70 | View |
| LT1121CST-5#TR | SOT | 3 | C | $1.76 | View | |
| LT1121CST-5#TRPBF | SOT | 3 | C | $1.76 | View | |
| LT1121CZ-3.3 | TO-92 | 3 | C | $1.58 | $1.30 | View |
| LT1121CZ-3.3#PBF | TO-92 | 3 | C | $1.58 | $1.30 | View |
| LT1121CZ-3.3#TR | TO-92 | 3 | C | $1.36 | View | |
| LT1121CZ-3.3#TRPBF | TO-92 | 3 | C | $1.36 | View | |
| LT1121CZ-5 | TO-92 | 3 | C | $1.58 | $1.30 | View |
| LT1121CZ-5#PBF | TO-92 | 3 | C | $1.58 | $1.30 | View |
| LT1121CZ-5#TR | TO-92 | 3 | C | $1.36 | View | |
| LT1121CZ-5#TRPBF | TO-92 | 3 | C | $1.36 | View | |
| LT1121HVCS8 | SO | 8 | C | $2.25 | $1.90 | View |
| LT1121HVCS8#PBF | SO | 8 | C | $2.25 | $1.90 | View |
| LT1121HVCS8#TR | SO | 8 | C | $1.96 | View | |
| LT1121HVCS8#TRPBF | SO | 8 | C | $1.96 | View | |
| LT1121HVIS8 | SO | 8 | I | $2.78 | $2.35 | View |
| LT1121HVIS8#PBF | SO | 8 | I | $2.78 | $2.35 | View |
| LT1121HVIS8#TR | SO | 8 | I | $2.41 | View | |
| LT1121HVIS8#TRPBF | SO | 8 | I | $2.41 | View | |
| LT1121IN8 | PDIP | 8 | I | $2.17 | $1.80 | View |
| LT1121IN8#PBF | PDIP | 8 | I | $2.17 | $1.80 | View |
| LT1121IN8-3.3 | PDIP | 8 | I | $2.17 | $1.80 | View |
| LT1121IN8-3.3#PBF | PDIP | 8 | I | $2.17 | $1.80 | View |
| LT1121IN8-5 | PDIP | 8 | I | $2.17 | $1.80 | View |
| LT1121IN8-5#PBF | PDIP | 8 | I | $2.17 | $1.80 | View |
| LT1121IS8 | SO | 8 | I | $2.42 | $1.95 | View |
| LT1121IS8#PBF | SO | 8 | I | $2.42 | $1.95 | View |
| LT1121IS8#TR | SO | 8 | I | $2.01 | View | |
| LT1121IS8#TRPBF | SO | 8 | I | $2.01 | View | |
| LT1121IS8-3.3 | SO | 8 | I | $2.42 | $1.95 | View |
| LT1121IS8-3.3#PBF | SO | 8 | I | $2.42 | $1.95 | View |
| LT1121IS8-3.3#TR | SO | 8 | I | $2.01 | View | |
| LT1121IS8-3.3#TRPBF | SO | 8 | I | $2.01 | View | |
| LT1121IS8-5 | SO | 8 | I | $2.42 | $1.95 | View |
| LT1121IS8-5#PBF | SO | 8 | I | $2.42 | $1.95 | View |
| LT1121IS8-5#TR | SO | 8 | I | $2.01 | View | |
| LT1121IS8-5#TRPBF | SO | 8 | I | $2.01 | View | |
| LT1121IST-3.3 | SOT | 3 | I | $2.58 | $2.05 | View |
| LT1121IST-3.3#PBF | SOT | 3 | I | $2.58 | $2.05 | View |
| LT1121IST-3.3#TR | SOT | 3 | I | $2.11 | View | |
| LT1121IST-3.3#TRPBF | SOT | 3 | I | $2.11 | View | |
| LT1121IST-5 | SOT | 3 | I | $2.58 | $2.05 | View |
| LT1121IST-5#PBF | SOT | 3 | I | $2.58 | $2.05 | View |
| LT1121IST-5#TR | SOT | 3 | I | $2.11 | View | |
| LT1121IST-5#TRPBF | SOT | 3 | I | $2.11 | View | |
| LT1121IZ-3.3 | TO-92 | 3 | I | $1.92 | $1.55 | View |
| LT1121IZ-3.3#PBF | TO-92 | 3 | I | $1.92 | $1.55 | View |
| LT1121IZ-3.3#TR | TO-92 | 3 | I | $1.61 | View | |
| LT1121IZ-3.3#TRPBF | TO-92 | 3 | I | $1.61 | View | |
| LT1121IZ-5 | TO-92 | 3 | I | $1.92 | $1.55 | View |
| LT1121IZ-5#PBF | TO-92 | 3 | I | $1.92 | $1.55 | View |
| LT1121IZ-5#TR | TO-92 | 3 | I | $1.61 | View | |
| LT1121IZ-5#TRPBF | TO-92 | 3 | I | $1.61 | View | |
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Demo Boards
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.Click here to view our complete list of demo boards
Applications
- Low Current Regulator
- Regulator for Battery-Powered Systems
- Post Regulator for Switching Supplies
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Simulate
LTspice IV is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. To download LTspice IV and other FREE simulation tools, please visit our Design Simulation page.
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Related models available in LTspice IV
LT1121-3.3
LT1121-5
LT1121
Technical Support
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- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
