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 h
The LT1121 family are micropower low‑dropout regulators with shutdown capability, designed for battery‑powered systems. They deliver up to 150 mA output current with a typical dropout voltage of 0.4 V and feature a very low quiescent current of 30 µA (16 µA in shutdown). The devices are stable with as little as 0.33 µF output capacitance and include reverse‑battery protection.
Four package options are offered (8‑lead PDIP, 8‑lead plastic SOP, 3‑lead SOT‑23, 3‑lead TO‑92). Detailed electrical characteristics, thermal resistance data, and application notes are provided to aid design of both fixed‑output (3.3 V, 5 V) and adjustable versions (3.8 V‑30 V).
| Maximum Output Current | 150 mA |
|---|---|
| Dropout Voltage (typical) | 0.4 V |
| Quiescent Current (normal operation) | 30 µA |
| Quiescent Current (shutdown) | 16 µA |
| Fixed Output Voltages | 3.3 V and 5 V |
| Adjustable Output Voltage Range | 3.8 V to 30 V |
| Minimum Stable Output Capacitance | 0.33 µF |
| Reverse Battery Protection | Yes |
The LT1121 typically has a dropout voltage of 0.4 V.
In shutdown the quiescent current drops to about 16 µA.
The LT1121 is offered in 8‑lead PDIP, 8‑lead plastic SOP, 3‑lead SOT‑23, and 3‑lead TO‑92 packages.
The regulator can supply up to 150 mA of output current.