AD8305ACP-R2 Analog Devices Inc, AD8305ACP-R2 Datasheet
AD8305ACP-R2
Specifications of AD8305ACP-R2
Related parts for AD8305ACP-R2
AD8305ACP-R2 Summary of contents
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FEATURES Optimized for fiber optic photodiode interfacing Measures current over 5 decades Law conformance 0.1 dB from Single- or dual-supply operation ( total) Full log-ratio capabilities Nominal slope of 10 mV/dB ...
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AD8305 TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications ..................................................................................... 3 Absolute Maximum Ratings ............................................................ 4 ESD Caution .................................................................................. 4 Pin Configuration and Function Descriptions ...
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SPECIFICATIONS 25° 200 kΩ, and VRDZ connected to VREF, unless otherwise noted REF Table 1. Parameter INPUT INTERFACE Specified Current Range Input Current ...
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AD8305 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Supply Voltage V − Input Current Internal Power Dissipation 1 θ JA Maximum Junction Temperature Operating Temperature Range Storage Temperature Range Lead Temperature (Soldering 60 sec) 1 With package die ...
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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Table 3. Pin Function Descriptions Pin No. Mnemonic Function 1 VRDZ Top of a Resistive Divider Network that Offsets V may also be connected to ground when bipolar outputs are to be provided. 2 VREF ...
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AD8305 TYPICAL PERFORMANCE CHARACTERISTICS 200 kΩ 25°C, unless otherwise noted REF A 1 –40°C, 0°C, +25°C, +70°C, +85° 1.4 ...
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I (A) REF Figure 9. V vs. I for Multiple Values of I LOG REF mA) ...
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AD8305 10 10nA 100nA 0 –10 –20 1mA –30 1µA –40 –50 100 1k 10k 100k FREQUENCY (Hz) Figure 15. Small Signal AC Response (5% Sine Modulation), from for I in Decade Steps from 10 nA ...
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MEAN + 3σ 0 MEAN – 3σ –0.5 –1.0 –1.5 –2.0 1n 10n 100n 1µ 10µ I (A) PD Figure 21. Law Conformance Error Distribution (3σ to Either Side of Mean) 2.0 1.5 MEAN + 3σ ...
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AD8305 MEAN + 3σ –2 MEAN – 3σ –4 –6 –8 –10 –40 –30 –20 – TEMPERATURE (°C) Figure 27. Slope Drift vs. Temperature (3σ to Either Side of ...
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GENERAL STRUCTURE The AD8305 addresses a wide variety of interfacing conditions to meet the needs of fiber optic supervisory systems, and is also useful in many nonoptical applications. These notes explain the structure of this unique style of translinear log ...
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AD8305 required to accommodate this situation (see the Using A Negative Supply section). The voltage generated by applying I LOG resistance of 4.55 kΩ, formed by the parallel combination of a 6.69 kΩ resistor to ground and ...
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C bypassing capacitor on VSUM. If board space limits the amount of external circuitry to the AD8305 it is possible to eliminate the transistor in Figure 34 is the recommended and connect the resistor divider ...
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AD8305 APPLICATIONS The AD8305 is easy to use in optical supervisory systems and in similar situations where a wide ranging current converted to its logarithmic equivalent, which is represented in decibel terms. Basic connections for measuring a ...
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CALIBRATION The AD8305 has a nominal slope and intercept of 200 mV/decade and 1 nA, respectively. These values are untrimmed, and the slope alone may vary as much as 7.5% over temperature. For this reason recommended that a ...
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AD8305 USING A NEGATIVE SUPPLY Most applications of the AD8305 require only a single supply of 3 5.5 V. However, to provide further versatility, dual supplies may be employed, as illustrated in Figure 37. 5V VPOS VRDZ BIAS ...
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LOG-RATIO APPLICATIONS It is often desirable to determine the ratio of two currents, for example, in absorbance measurements. These are commonly used to assess the attenuation of a passive optical component, such as an optical filter or variable optical attenuator. ...
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AD8305 REVERSING THE INPUT POLARITY Some applications may require interfacing to a circuit that sources current rather than sinks current, such as connecting to the cathode side of a photodiode. Figure 40 shows the use of a current mirror circuit. ...
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CHARACTERIZATION METHODS During the characterization of the AD8305, the device was treated as a precision current-input logarithmic converter, because it is not practical for several reasons to generate accurate photocurrents by illuminating a photodiode. The test currents are generated by ...
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AD8305 The setup shown in Figure 44 was used for frequency response measurements of the logarithmic amplifier section. The AD8138 output is offset to 1 and modulated to a depth frequency chosen (over ...
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EVALUATION BOARD An evaluation board is available for the AD8305, the schematic for which is shown in Figure 49. It can be configured for a wide variety of experiments. The buffer gain is factory-set to unity, providing a slope of ...
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AD8305 Figure 47. Component Side Layout Figure 48. Component Side Silkscreen Rev Page ...
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R20 OPEN R17 VRDZ OPEN R7 0Ω R18 VREF OPEN R1 200kΩ IREF OPEN R13 1kΩ 1nF 2 SC-STYLE PD 3 INPT LK1 R9 C11 OPEN 1nF VSUM COMM COMM COMM COMM ...
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... MAX 1.00 0.85 0.80 SEATING PLANE ORDERING GUIDE 1 Model Temperature Range AD8305ACP-R2 −40°C to +85°C AD8305ACP-REEL7 −40°C to +85°C AD8305ACPZ-R2 −40°C to +85°C AD8305ACPZ-RL7 −40°C to +85°C AD8305-EVALZ RoHS Compliant Part; # denotes lead-free product may be top or bottom marked. ...