The ADL5315 is a high-side monitor that provides a compact solution for the common and often challenging problem of interfacing an optical power-monitoring device, such as a logarithmic amplifier, to the cathode-side of a PIN photodiode. The ADL5315 mirrors the current at the cathode at a 1:1 ratio over a six-decade range.

The ADL5315 offers unmatched accuracy, with linearity of only 1% over a wide operating range of six decades—from 3 nA to 3 mA. In PIN photodiode modules where only the cathode is available for connection, the high linearity allows the device to be paired with linear or logarithmic amplifiers to form a complete, precise optical power measurement system. Although the ADL5315 is optimized for use with PIN photodiodes, its operating range makes it suitable for a broad array of applications that require accurate current mirroring.

The ADL5315 features an adjustable input current limit to protect the photodiode from damage caused by excessive input current. Its miniature single-chip 2 mm × 3 mm package makes it well suited for space-constrained applications, such as SFP optical transceiver modules. The ADL5315, which is fully specified from –40° to 85°C, operates from a single 2.7- to 8-V supply. The device costs $1.93 per unit in 1,000-piece quantities.

Analog Devices, Inc.
www.analog.com