Generator IC's low-noise & ripple suits sensitive circuits

16th September 2015

Barney Scott

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Datasheet

Linear Technology Corporation announces the LT3095, a dual-channel IC delivering two very low noise, low ripple bias supplies from a single input. Each channel incorporates a monolithic step-up DC/DC converter post-regulated by an integrated ultralow noise and high PSRR (power supply rejection ratio) linear regulator.

The LT3095 delivers up to 50mA of continuous output current at output voltages up to 20V with total ripple and noise under 100µV_P-P. The device operates from a 3-20V input voltage range, making it compatible with a variety of power sources.

The LT3095’s fixed-frequency, peak current-mode step-up DC/DC converters include an integrated 950mA power switch, Schottky diode and internal frequency compensation. Switching frequency is programmable between 450kHz and 2MHz via a single resistor or synchronisable to an external clock, enabling the use of tiny external components. Combined with a compact 3x5mm QFN package, the LT3095 offers a simple, compact solution footprint with good efficiency for instrumentation amplifiers, RF and data conversion systems, and other low noise biasing applications.

The LT3095’s linear regulators employ Linear’s proprietary current-source reference architecture, providing numerous benefits such as single-resistor output voltage setting capability and bandwidth, noise, PSRR and load regulation performance virtually independent of output voltage. Integrated output noise (in a 10Hz to 100kHz bandwidth) is a mere 4µV_RMS and PSRR exceeds 70dB over the entire switching frequency range, resulting in total noise and ripple under 100µV_P-P. The linear regulator adjusts the step-up converter’s output voltage to 2V above the linear regulator’s output voltage, optimising power dissipation, transient response and PSRR performance. To enhance system reliability, the LT3095 offers short-circuit and thermal protection, as well as providing independent precision enable/UVLO thresholds for each channel. Micropower operation results from both EN pins being pulled low.

The LT3095’s symmetric pinout simplifies PCB design. The device is housed in a thermally enhanced, 3x5mm QFN-24 package, in both industrial E- & I-grade with -40 to +125°C temperature range, and military MP-grade versions operating from -55 to +125°C. The E grade is priced at $2.95 in 1,000 piece quantities and all versions are available from stock.