ADL5306 60 dB-RANGE (100 nA-100 µA) Low-Cost Logarithmic Converter

The ADL5306 is a low cost micro-miniature logarithmic converter optimized for the determination of optical power in fiber-optic systems. It uses an advanced implementation of a classic translinear (junction-based) technique to provide a large dynamic range in a versatile and easily-used form. A single supply voltage of between 3 V and 5.5 V is adequate; dual supplies may optionally be used. The low quiescent current (typically 5 mA) permits use in battery-operating applications

The input current IPD of 100 nA to 100 µA applied to the INPT pin is the collector current of an optimally-scaled NPN transistor, which converts this current to a voltage (its VBE) with a precise logarithmic relationship. A second such converter is used to handle the reference current, IREF, applied to pin IREF. These input nodes are biased slightly above ground (0.5 V). This is generally acceptable for photodiode applications where the anode does not need to be grounded. Similarly, this bias voltage is easily accounted for in generating IREF. The output of the logarithmic front-end is available at pin VLOG.

Features and Benefits

Optimized for fiber optic photodiode interfacing

Measures current over 3 decades
Law conformance 0.1 dB from 100 nA to 100 µA

Single- or dual-supply operation (3 V to ±5.5 V total)

Nominal slope of 10 mV/dB (200 mV/decade)

Nominal intercept of 1 nA (set by external resistor)
Optional adjustment of slope and intercept

Full log-ratio capabilities

Temperature stable

Rapid response time for a given current level

Miniature 16-lead chip scale package
(LFCSP 3 mm × 3 mm)

Low power: ~5 mA quiescent current

Optical

Translinear Logarithmic Amplfiers

Amplifiers

non-RMS Responding Power Detectors

Data Sheets

Document	note
ADL5306: 60dB-range (100nA to 100µA) Low-Cost Logarithmic Converter Data Sheet (Rev. 0)	PDF 1015 kB

Application Notes

Document	note
AN-643: Closed-Loop Control Circuit Implementation of the ADuC832 MicroConverter®IC and the AD8305 Logarithmic Converter in a Digital Variable Optical Attenuator (Rev. 0)	PDF 395 kB

Order Information

Part Number	Package	Packing Qty	Temp Range	Price 1000+	RoHS
ADL5306ACP-R2 Obsolete	16 ld LFCSP (3x3mm, 1.50mm exposed pad)	REEL 250		0	N
ADL5306ACP-REEL7 Obsolete	16 ld LFCSP (3x3mm, 1.50mm exposed pad)	REEL 1500		0	N
ADL5306ACP-WP Obsolete	16 ld LFCSP (3x3mm, 1.50mm exposed pad)	REEL 50		0	N
ADL5306ACPZ-R2 Production	16 ld LFCSP (3x3mm, 1.50mm exposed pad)	REEL 250	-40 to 85C	5.22	Y
ADL5306ACPZ-REEL7 Production	16 ld LFCSP (3x3mm, 1.50mm exposed pad)	REEL 1500	-40 to 85C	4.75	Y