DESCRIPTION

The LT3011 is a high voltage, micropower, low dropout linear regulator. The device is capable of supplying 50mA of output current with a dropout voltage of 300mV. Designed for use in battery-powered high voltage systems, the low quiescent current (46μA operating and 1μA in shutdown) is well controlled in dropout, making the LT3011 an ideal choice.

The LT3011 includes a PWRGD flag to indicate output regulation. The delay between regulated output level and flag indication is programmable with a single capacitor. The LT3011 also has the ability to operate with very small output capacitors; it is stable with only 1μF on the output. Small ceramic capacitors can be used without the addition of any series resistance (ESR) as is common with other regulators. Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting, and reverse current protection.

The LT3011 features an adjustable output with a 1.24V reference voltage. The device is available in the thermally enhanced 12-lead MSOP and the low profile (0.75mm) 10-pin (3mm × 3mm) DFN package, both providing excellent thermal characteristics.

 

FEATURES

Wide Input Voltage Range: 3V to 80V

Low Quiescent Current: 46μA

Low Dropout Voltage: 300mV

Output Current: 50mA

PWRGD Flag with Programmable Delay

No Protection Diodes Needed

Adjustable Output from 1.24V to 60V

1μA Quiescent Current in Shutdown

Stable with 1μF Output Capacitor

Stable with Ceramic, Tantalum, and Aluminum Capacitors

Reverse-Battery Protection

No Reverse Current Flow from Output to Input

Thermal Limiting

Thermally Enhanced 12-Lead MSOP and 10-Pin (3mm × 3mm) DFN Packages

 

APPLICATIONS

Low Current High Voltage Regulators

Regulator for Battery-Powered Systems

Telecom Applications

Automotive Applications

 

APPLICATIONS INFORMATION

The LT3011 is a 50mA high voltage/low dropout regulator with micropower quiescent current and shutdown. The device is capable of supplying 50mA at a dropout voltage of 300mV. The low operating quiescent current (46μA) drops to 1μA in shutdown. In addition to low quiescent current, the LT3011 incorporates several protection features which make it ideal for use in battery-powered systems. The device is protected against both reverse input and reverse output voltages. In battery backup applications where the output can be held up by a backup battery when the input is pulled to ground, the LT3011 acts like it has a diode in series with its output and prevents reverse current flow.

Adjustable Operation

The LT3011 has an output voltage range of 1.24V to 60V. The device servos the output to maintain the voltage at the adjust pin at 1.24V referenced to ground. The current in R1 is then equal to 1.24V/R1 and the current in R2 is the current in R1 plus the ADJ pin bias current. The ADJ pin bias current, 30nA at 25°C, flows through R2 into the ADJ pin. The value of R1 should be less than 250k to minimize errors in the output voltage caused by the ADJ pin bias current. Note that in shutdown the output is turned off and the divider current will be zero. The adjustable device is tested and specified with the ADJ pin tied to the OUT pin and a 5μA DC load (unless otherwise specified) for an output voltage of 1.24V. Specifications for output voltages greater than 1.24V will be proportional to the ratio of the desired output voltage to 1.24V; (VOUT/1.24V).

Output Capacitance and Transient Response

The LT3011 is designed to be stable with a wide range of output capacitors. The ESR of the output capacitor affects stability, most notably with small capacitors. A minimum output capacitor of 1μF with an ESR of 3Ω or less is recommended to prevent oscillations. The LT3011 is a micropower device and output transient response will be a function of output capacitance. Larger values of output capacitance decrease the peak deviations and provide improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT3011, will increase the effective output capacitor value.