The LT1579 is a dual input, single output, low dropout regulator designed to provide an uninterruptible output voltage from two independent input voltage sources on a priority basis. All of the circuitry needed to switch smoothly and automatically between inputs is incorporated. The LT1579 can supply 300mA of output current from either input at a dropout voltage of 0.4V. Quiescent current is 50µA, dropping to 7µA in shutdown. Two comparators are included to monitor input voltage status. Two additional status flags indicate which input is supplying power and provide an early warning against loss of output regulation when both inputs are low. A secondary select pin is provided so that the user can force the device to switch from the primary input to the secondary input. Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse-current protection. The device is available in fixed output voltages of 3V, 3.3V and 5V, and as an adjustable device with a 1.5V reference voltage. The LT1579 regulators are available in narrow 16-lead SO and 16-lead SSOP packages with all features, and in SO-8 with limited features.
The LT1579 is a dual input, single output, low dropout regulator designed to provide an uninterruptible output voltage from two independent input voltage sources on a priority basis. The device incorporates all circuitry needed to switch smoothly and automatically between inputs, ensuring continuous power delivery even if one source fails or drops below the regulation threshold.
Key features include a maximum output current of 300mA with a dropout voltage as low as 0.4V, adjustable output voltages from 1.5V to 20V (or fixed options of 3V, 3.3V, and 5V), and internal protection against reverse battery and reverse current. The regulator includes two low-battery comparators and status flags to aid in power management applications such as dual battery systems.
| Output Current | 300mA |
|---|---|
| Dropout Voltage (Nominal) | 0.4V |
| Quiescent Current | 50uA |
| Shutdown Quiescent Current | 7pA |
| Output Voltage Range (Adjustable) | 1.5V to 20V |
| Fixed Output Voltages | 3V, 3.3V and 5V |
| Operating Junction Temperature Range | 0°C to 125°C |
The device can supply up to 300mA of output current from either input.
No, the device does not need protection diodes as it includes internal reverse-battery and reverse-current protection.
The regulator is available in fixed output voltages of 3V, 3.3V, and 5V.