20V, 1A, Ultralow Noise, Ultrahigh PSRR Negative Linear Regulator

The LT3099 is a high-performance, low-dropout negative linear regulator featuring Analog Devices, Inc.’s ultralow noise and ultrahigh power-supply rejection ratio (PSRR) architecture for powering noisesensitive applications. Designed as a precision current reference followed by a high-performance voltage buffer, the LT3099 can be easily paralleled to reduce noise further, increase output current, and spread heat on the PCB.

The device supplies 1A at a typical 350mV dropout voltage. The operating quiescent current is nominally 2.9mA and drops to 5μA in shutdown. The LT3099’s wide output voltage range (0V to -19V) error amplifier operates at unity gain and provides virtually constant output noise, PSRR, bandwidth, and load regulation independent of the programmed output voltage. Additionally, the regulator features a bi-directional enable pin, programmable current limit, fast start-up capability, and programmable power good for indicating output voltage regulation. The regulator incorporates a tracking function to control an upstream supply to maintain a constant voltage across the LT3099 and minimize power dissipation.

Built-in protection includes an internal current limit with foldback and a thermal limit with hysteresis. The LT3099 is available in a thermally enhanced 4mm × 3mm DFN package.

APPLICATIONS

* RF Power Supplies and Precision Power Supplies

* Very Low Noise Instrumentation

* High-speed/High-precision Data Converters

* Medical Applications: Diagnostics and Imaging

* Post-regulator for Switching Supplies

* Ultralow RMS Noise: 1.4μVRMS (10Hz to 100kHz)

* Ultralow Spot Noise: 4nV/√Hz at 10kHz

* Ultrahigh PSRR: 75dB at 1MHz

* Output Current: 1A

* Wide Input Voltage Range: -3.5V to -20V

* Single Capacitor Improves Noise and PSRR

* 100μA SET Pin Current: ±0.5% Initial Accuracy

* Single Resistor Programs Output Voltage

* Programmable Current Limit

* Low Dropout Voltage: 350mV