AD8305 is a 100 dB dynamic range 10 nA to 1 mA current converter produced by Analog Devices. It has the following features: 1. Optimized for fiber optic photodiode interface; 2. Measures current over 5 decades; 3. Conforms to 0.1 dB from 10 nA to 1 mA of the law; 4. Single- or dual-supply operation (3 V to 12 V total); 5. Has full log-ratio capabilities; 6. Nominal slope of 10 mV/dB (200 mV/decade); 7. Nominal intercept of 1 nA (set by external resistor); 8. Optional adjustment of slope and intercept; 9. Completely and temperature stable; 10. Rapid response time for a given current level; 11. Miniature 16-lead chip scale package (LFCSP 3 mm × 3 mm); 12. Low power: ~5 mA quiescent current.
The AD8305 is an inexpensive microminiature logarithmic converter optimized for determining optical power in fiber‑optic systems. It offers a 100 dB dynamic range, single‑ or dual‑supply operation (3 V to 12 V), and a low quiescent current of about 5 mA, making it suitable for battery‑powered applications.
The device is supplied in a 16‑lead LFCSP (3 mm × 3 mm) package and includes a buffer amplifier capable of sourcing up to 25 mA. Detailed specifications cover logarithmic slope and intercept, input current range (10 nA–1 mA), temperature range (‑40 °C to +85 °C), and absolute maximum ratings.
| Logarithmic Slope | 200 mV/dec (typ) |
|---|---|
| Logarithmic Intercept | 1 nA (typ) |
| Quiescent Current | ~5 mA |
| Supply Voltage Range | 3 V – 12 V (single or dual) |
| Operating Temperature Range | ‑40 °C to +85 °C |
| Maximum Output Current Sourcing | 20 mA |
It operates from a single supply of 3 V to 12 V, or dual supplies within the same total range.
The device draws about 5 mA of quiescent current.
It is offered in a 16‑lead LFCSP package measuring 3 mm × 3 mm.