ADI LT3571EUD#PBF

High APD Voltage: Up to 70V Integrated Schottky Diode 75V, 370mA Internal Switch High-Side Fixed Voltage Drop APD Current Monitor Adjustable Frequency: 250kHz to 2MHz Frequency Synchronization Wide Voltage Range: 2.7V to 20V Constant Voltage and Constant Current Regulation Programmable Current Limit Protection Surface Mount Component Low Shutdown Current <1μA Internal Soft-Start Internal Compensation CTRL Pin Allows Output Adjustment Without Polarity Reversal 3mm x 3mm 16-Pin QFN Package

The LT3571 is a current mode boost DC/DC converter designed to bias avalanche photodiodes (APDs) in optical receivers, with output voltage up to 75V. The LT3571 features a high-side fixed voltage drop APD current monitor with better than 10% relative accuracy over the full temperature range. The integrated power switch, Schottky diode, and APD current monitor enable a compact, low-cost solution. It combines a conventional voltage loop with a unique current loop, allowing operation as either a constant current source or constant voltage source. The inductor-based topology ensures the input is protected from switching noise. The integrated high-side current monitor produces a current proportional to the APD current, with better than 10% relative accuracy over a dynamic range spanning four decades for input currents from 250nA to 2.5mA. This current can be used as a reference to provide digitally programmed output voltage via the CTRL pin. The LT3571 is housed in a compact 3mm x 3mm 16-pin QFN package.