LT1129 - Micropower Low Dropout Regulators with Shutdown
Datasheet 
DocumentationDatasheet
Application Note
- AN51 - Power Conditioning for Notebook and Palmtop Systems
- AN58 - 5V to 3.3V Converters for Microprocessor Systems
- AN65 - A Fourth Generation of LCD Backlight Technology
Design Note
- DN74 - Techniques for Deriving 3.3V from 5V Supplies
- DN82 - 5V to 3.3V Regulator with Fail-Safe Switchover
- DN91 - 5V to 3.3V Circuit Collection
Reliability Data
cad_symbol
ltspice
Features
- 400mV Dropout Voltage
- 700mA Output Current
- 50μA Quiescent Current
- No Protection Diodes Needed
- Adjustable Output from 3.8V to 30V
- 3.3V and 5V Fixed Output Voltages
- Controlled Quiescent Current in Dropout
- Shutdown
- 16μA Quiescent Current in Shutdown
- Stable with 3.3μF Output Capacitor
- Reverse Battery Protection
- No Reverse Output Current
- Thermal Limiting
- Surface Mount SOT-223 and DD-Pak Packages
Typical Application
Description
The LT1129/LT1129-3.3/LT1129-5 are micropower low dropout regulators with shutdown. The devices are capable of supplying 700mA of output current with a dropout voltage of 400mV at maximum output. Designed for use in battery-powered systems, the low quiescent current, 50μA operating and 16μA in shutdown, make them an ideal choice. The quiescent current does not rise in dropout as it does with many other low dropout PNP regulators.Other features of the LT1129 /LT1129-3.3/LT1129-5 include the ability to operate with small output capacitors. They are stable with only 3.3μF on the output while most older devices require between 10μF and 100μF for stability. Also the input may be connected to ground or a reverse voltage without reverse current flow from output to input. This makes the LT1129/LT1129-3.3/LT1129-5 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. The devices are available in 5-lead TO-220, 5-lead DD-Pak and 3-lead SOT-223 packages.
DDPAK-5,SO-8,SOT-223,TO-220
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LT1129CQ#PBF | DD PAK | 5 | C | $3.08 | $2.45 |
| LT1129CQ#TRPBF | DD PAK | 5 | C | $2.57 | |
| LT1129CQ-3.3#PBF | DD PAK | 5 | C | $3.08 | $2.45 |
| LT1129CQ-3.3#TRPBF | DD PAK | 5 | C | $2.57 | |
| LT1129CQ-5#PBF | DD PAK | 5 | C | $3.08 | $2.45 |
| LT1129CQ-5#TRPBF | DD PAK | 5 | C | $2.57 | |
| LT1129CS8#PBF | SO | 8 | C | $3.17 | $2.50 |
| LT1129CS8#TRPBF | SO | 8 | C | $2.56 | |
| LT1129CS8-3.3#PBF | SO | 8 | C | $3.17 | $2.50 |
| LT1129CS8-3.3#TRPBF | SO | 8 | C | $2.56 | |
| LT1129CS8-5#PBF | SO | 8 | C | $3.17 | $2.50 |
| LT1129CS8-5#TRPBF | SO | 8 | C | $2.56 | |
| LT1129CST-3.3#PBF | SOT | 3 | C | $2.83 | $2.30 |
| LT1129CST-3.3#TRPBF | SOT | 3 | C | $2.36 | |
| LT1129CST-5#PBF | SOT | 3 | C | $2.83 | $2.30 |
| LT1129CST-5#TRPBF | SOT | 3 | C | $2.36 | |
| LT1129CT#PBF | TO-220 | 5 | C | $2.67 | $2.15 |
| LT1129CT-3.3#06PBF | TO-220 | 5 | C | $2.67 | $2.15 |
| LT1129CT-3.3#PBF | TO-220 | 5 | C | $2.67 | $2.15 |
| LT1129CT-5#06PBF | TO-220 | 5 | C | $2.67 | $2.15 |
| LT1129CT-5#PBF | TO-220 | 5 | C | $2.67 | $2.15 |
| LT1129IQ#PBF | DD PAK | 5 | I | $3.67 | $2.95 |
| LT1129IQ#TRPBF | DD PAK | 5 | I | $3.07 | |
| LT1129IQ-3.3#PBF | DD PAK | 5 | I | $3.67 | $2.95 |
| LT1129IQ-3.3#TRPBF | DD PAK | 5 | I | $3.07 | |
| LT1129IQ-5#PBF | DD PAK | 5 | I | $3.67 | $2.95 |
| LT1129IQ-5#TRPBF | DD PAK | 5 | I | $3.07 | |
| LT1129IS8#PBF | SO | 8 | I | $3.75 | $2.95 |
| LT1129IS8#TRPBF | SO | 8 | I | $3.01 | |
| LT1129IS8-3.3#PBF | SO | 8 | I | $3.75 | $2.95 |
| LT1129IS8-3.3#TRPBF | SO | 8 | I | $3.01 | |
| LT1129IS8-5#PBF | SO | 8 | I | $3.75 | $2.95 |
| LT1129IS8-5#TRPBF | SO | 8 | I | $3.01 | |
| LT1129IST-3.3#PBF | SOT | 3 | I | $3.17 | $2.60 |
| LT1129IST-3.3#TRPBF | SOT | 3 | I | $2.66 | |
| LT1129IST-5#PBF | SOT | 3 | I | $3.17 | $2.60 |
| LT1129IST-5#TRPBF | SOT | 3 | I | $2.66 | |
| LT1129IT#06PBF | TO-220 | 5 | I | $3.17 | $2.60 |
| LT1129IT#PBF | TO-220 | 5 | I | $3.17 | $2.60 |
| LT1129IT-3.3#PBF | TO-220 | 5 | I | $3.17 | $2.60 |
| LT1129IT-5#06PBF | TO-220 | 5 | I | $3.17 | $2.60 |
| LT1129IT-5#PBF | TO-220 | 5 | I | $3.17 | $2.60 |
| LT1129MPST-3.3 | SOT | 3 | MP | $10.03 | $7.02 |
| LT1129MPST-3.3#PBF | SOT | 3 | MP | $10.03 | $7.02 |
| LT1129MPST-3.3#TR | SOT | 3 | MP | $7.08 | |
| LT1129MPST-3.3#TRPBF | SOT | 3 | MP | $7.08 | |
| LT1129CQ | DD PAK | 5 | C | $6.16 | $4.90 |
| LT1129CQ#TR | DD PAK | 5 | C | $5.14 | |
| LT1129CQ-3.3 | DD PAK | 5 | C | $6.16 | $4.90 |
| LT1129CQ-3.3#TR | DD PAK | 5 | C | $5.14 | |
| LT1129CQ-5 | DD PAK | 5 | C | $6.16 | $4.90 |
| LT1129CQ-5#TR | DD PAK | 5 | C | $5.14 | |
| LT1129CS8 | SO | 8 | C | $6.34 | $5.00 |
| LT1129CS8#TR | SO | 8 | C | $5.12 | |
| LT1129CS8-3.3 | SO | 8 | C | $6.34 | $5.00 |
| LT1129CS8-3.3#TR | SO | 8 | C | $5.12 | |
| LT1129CS8-5 | SO | 8 | C | $6.34 | $5.00 |
| LT1129CS8-5#TR | SO | 8 | C | $5.12 | |
| LT1129CST-3.3 | SOT | 3 | C | $5.66 | $4.60 |
| LT1129CST-3.3#TR | SOT | 3 | C | $4.72 | |
| LT1129CST-5 | SOT | 3 | C | $5.66 | $4.60 |
| LT1129CST-5#TR | SOT | 3 | C | $4.72 | |
| LT1129CT | TO-220 | 5 | C | $5.34 | $4.30 |
| LT1129CT-3.3 | TO-220 | 5 | C | $5.34 | $4.30 |
| LT1129CT-5 | TO-220 | 5 | C | $5.34 | $4.30 |
| LT1129IQ | DD PAK | 5 | I | $7.34 | $5.90 |
| LT1129IQ#TR | DD PAK | 5 | I | $6.14 | |
| LT1129IQ-3.3 | DD PAK | 5 | I | $7.34 | $5.90 |
| LT1129IQ-3.3#TR | DD PAK | 5 | I | $6.14 | |
| LT1129IQ-5 | DD PAK | 5 | I | $7.34 | $5.90 |
| LT1129IQ-5#TR | DD PAK | 5 | I | $6.14 | |
| LT1129IS8 | SO | 8 | I | $7.50 | $5.90 |
| LT1129IS8#TR | SO | 8 | I | $6.02 | |
| LT1129IS8-3.3 | SO | 8 | I | $7.50 | $5.90 |
| LT1129IS8-3.3#TR | SO | 8 | I | $6.02 | |
| LT1129IS8-5 | SO | 8 | I | $7.50 | $5.90 |
| LT1129IS8-5#TR | SO | 8 | I | $6.02 | |
| LT1129IST-3.3 | SOT | 3 | I | $6.34 | $5.20 |
| LT1129IST-3.3#TR | SOT | 3 | I | $5.32 | |
| LT1129IST-5 | SOT | 3 | I | $6.34 | $5.20 |
| LT1129IST-5#TR | SOT | 3 | I | $5.32 | |
| LT1129IT | TO-220 | 5 | I | $6.34 | $5.20 |
| LT1129IT-3.3 | TO-220 | 5 | I | $6.34 | $5.20 |
| LT1129IT-5 | TO-220 | 5 | I | $6.34 | $5.20 |
| LT1129CT-5#06 | TO-220 | 5 | C | $5.34 | $4.30 |
| LT1129CT-5#30 | TO-220 | 5 | C | ||
| LT1129CT-5#31 | TO-220 | 5 | C |
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.