120 dB RANGE (3 nA TO 3 mA) Dual Logarithmic Converter
The ADL5310 is a low-cost dual logarithmic amplifier that converts input current over a wide dynamic range to a linear-in-dB output voltage. It is optimized for the determination of optical power in wide-ranging optical communication system applications including control circuitry for lasers, optical switches, attenuators, and amplifiers, as well as general system monitoring. The device is equivalent to a dual AD8305 with enhanced dynamic range (120 dB). While the ADL5310 contains two independent signal channels with individually-configurable transfer function constants (slope and intercept), internal bias circuitry is shared between channels for improved power consumption and channel matching. Dual converters in a single compact LFCSP package yield space-efficient solutions for measuring gain or attenuation across optical elements. Only a single supply is required, while optional dual supply operation offers added flexibility.
The ADL5310 employs an optimized translinear structure, which utilizes the accurate logarithmic relationship between a bipolar transistor's base-emitter voltage and collector current, with appropriate scaling by precision currents to compensate the inherent temperature dependence. Input and reference current pins sink current ranging from 3 nA to 3 mA (limited to ±60 dB between input and reference) into a fixed voltage defined by the VSUM potential, which is internally set to 500 mV but may be externally-grounded for dual-supply operation and additional applications requiring voltage inputs.
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
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