Analog Devices' high-side monitor provides a compact solution for the 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, producing an output that's equal to the reference current monitored.
The device offers a linearity of 1% over the six-decade operating range, 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. While 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 2- by 3-mm package suits it for space-constrained applications, such as SFP (small form factor pluggable) optical transceiver modules. The ADL5315 is fully specified from -40°C to +85°C, and operates from a single 2.7- to 8-V supply. The device is priced at $1.93 in 1000-piece quantities. For more information, visit www.analog.com/ADL5315.