Datasheet ADL5315 (Analog Devices)

Precision Wide Range (3 nA to 3 mA) High-Side Current Mirror Data Sheet ADL5315 FEATURES FUNCTIONAL BLOCK DIAGRAM Accurately mirrors input current (1:1 ratio) over 6 decades ADL5315 Linearity 1% from 3 nA to 3 mA Stable mirror input voltage VOLTAGE CURRENT REFERENCE LIMITING Voltage held 1 V below supply using internal reference 4 5 or can be set externally COMM RLIM Adjustable input current limit 20k CURRENT MIRROR 2.7 V to 8 V single-supply operation 3 1:1 6 SREF VPOS Miniature 8-lead LFCSP (2 mm × 3 mm) VSET NC 2 7 APPLICATIONS INPT IOUT Optical power monitoring from a single photodiode 1 8 IPD IPD General voltage biasing with precision current monitoring
05694-001
Voltage-to-current conversion
Figure 1.
GENERAL DESCRIPTION
The ADL5315 is a wide input current range, precision high-side The VSET input has very low input current and can be driven current mirror featuring a stable and user-adjustable input as low as the bottom rail, facilitating nonloading voltage-to- voltage. It is optimized for use with PIN photodiodes, but its current conversion as well as minimizing dark current in flexibility and wide operating range make it suitable for a broad photodiode applications. array of additional applications. Over the 3 nA to 3 mA range, the current sourced from the INPT pin is accurately mirrored The ADL5315 also features adjustable input current limiting with a 1:1 ratio and sourced from the IOUT output pin. In a using an external resistor from RLIM to VPOS. The maximum typical photodiode application, the output drives a current- current sourced by INPT (and IOUT) can be set between 1 mA input logarithmic amplifier to produce a linear-in-dB output and 16 mA, beyond which the voltage at INPT falls rapidly representing the optical power incident upon the photodiode. from its setpoint. Connecting RLIM directly to VPOS provides For linear voltage output, a single resistor to ground is all that is basic input short-circuit protection with the default current required. The photodiode anode can be connected to a high limit of 16 mA typical. speed transimpedance amplifier for the extraction of the data The ADL5315 is available in a 2 mm × 3 mm, 8-lead LFCSP and stream. The voltage at the INPT pin is temperature stable with is specified for operation from −40°C to +85°C. respect to the voltage at the VSET input pin, which it tracks. A temperature stable reference voltage is provided at the SREF pin, which, when tied to VSET, fixes the voltage at INPT 1.0 V below VPOS. VSET can also be driven from an external source.
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION BIAS CONTROL INTERFACE NOISE PERFORMANCE MIRROR RESPONSE TIME INPUT CURRENT LIMITING APPLICATIONS AVERAGE POWER MONITORING TRANSLINEAR LOG AMP INTERFACING EXTENDED OPERATING RANGE USING RLIM AS A SECONDARY MONITOR CHARACTERIZATION METHODS EVALUATION BOARD OUTLINE DIMENSIONS ORDERING GUIDE