AD8305ACP-REEL7

Overview

The AD8305 is a microminiature logarithmic converter optimized for fiber optic systems, utilizing translinear junction-based techniques. It provides a wide dynamic range of 100 dB (10 nA to 1 mA) with a nominal slope of 10 mV/dB and intercept at 1 nA. Operating on a single supply from 3 V to 12 V or dual supplies, it features low quiescent current (~5 mA). The device includes an internal buffer amplifier capable of driving substantial loads with rail-to-rail output swing within 100 mV of the rails. It is housed in a 16-lead LFCSP package and operates over a temperature range of −40°C to +85°C.

Feature Summary

• Optimized for fiber optic photodiode interfacing with law conformance of 0.1 dB across the specified current range.
• Supports full log-ratio capabilities by accepting numerator and denominator currents at dedicated input pins.
• Includes a buffer amplifier for raising the basic slope, implementing precision comparators, or creating low-pass filters.

Applications

• Optical power measurement
• Wide range baseband logarithmic compression
• Measurement of current and voltage ratios
• Optical absorbance measurement

Procurement Notes

Verify the specific ordering suffix matches the required package type and reel configuration. Confirm that the component revision aligns with the design requirements. Ensure proper handling procedures are followed due to the miniature package format. Check datasheet specifications against system constraints before finalizing procurement decisions.

Selection Notes

Select this component when a wide dynamic range logarithmic conversion is required for optical applications. Consider the 100 dB range and 10 mV/dB slope for precise signal processing. Evaluate the low quiescent current for battery-operated designs. Ensure the operating temperature range meets environmental conditions.

Part Context

The AD8305 belongs to Analog Devices' family of logarithmic converters designed for high-dynamic-range applications. It employs advanced translinear technology to convert input currents into proportional logarithmic voltages. This series is particularly noted for its optimization in fiber optic supervisory systems and general current-to-voltage logarithmic conversion tasks.

Replacement Considerations

The AD8304 offers a wider 160 dB dynamic range but requires different biasing considerations. Both devices utilize similar translinear principles but differ in input current ranges and package options. Verify pin compatibility and external component requirements when substituting.