Datasheet AD8475 (Analog Devices)

Precision, Selectable Gain, Ful y Differential Funnel Amplifier Data Sheet AD8475 FEATURES FUNCTIONAL BLOCK DIAGRAMS Precision attenuation: G = 0.4, G = 0.8 4x Fully differential or single-ended input/output N 0. S S S I + –V –V –V Differential output designed to drive precision ADCs 16 15 14 13 Drives switched capacitor and Σ-Δ ADCs Rail-to-rail output 1kΩ VOCM pin adjusts output common-mode voltage +IN 0.4x 1 12 NC 1.25kΩ Robust overvoltage protection up to ±15 V (V 1.25kΩ S = +5 V) +IN 0.8x 2 11 –OUT Single supply: 3 V to 10 V 1.25kΩ AD8475 Dual supplies: ±1.5 V to ±5 V –IN 0.8x 3 10 +OUT High performance 1.25kΩ 1kΩ Suited for driving 18-bit converters up to 4 MSPS –IN 0.4x 4 9 VOCM 10 nV/√Hz output noise 3 ppm/°C gain drift 5 6 7 8 500 μV maximum output offset S S S 4x +V +V +V 50 V/μs slew rate N 0.
001
–I Low power: 3.2 mA supply current NC = NO CONNECT
09432- Figure 1. 16-Lead LFCSP
APPLICATIONS 8x 4x ADC drivers S UT IN 0. IN 0. Differential instrumentation amplifier building blocks + + –V NC –O 9 8 7 6 Single-ended-to-differential converters 10 1kΩ GENERAL DESCRIPTION 1.25kΩ
The AD8475 is a fully differential, attenuating amplifier with
1.25kΩ
integrated precision gain resistors. It provides precision attenuation
1.25kΩ AD8475
(by 0.4 or 0.8), common-mode level shifting, and single-ended-to-
1.25kΩ 1kΩ
differential conversion along with input overvoltage protection. Power dissipation on a single 5 V supply is only 16 mW.
1 2 3 4 5 S
The AD8475 is a simple to use, fully integrated precision gain
8x 4x UT +V CM O O +
block, designed to process signal levels of up to ±10 V on a single
N 0. N 0. V –I –I
002 supply. It provides a complete interface to make industrial level
NC = NO CONNECT
09432- signals directly compatible with the differential input ranges of low Figure 2. 10-Lead MSOP voltage high performance 16-bit or 18-bit single-supply successive The AD8475 works extremely well with SAR, Σ-Δ, and pipeline approximation (SAR) analog-to-digital converters (ADCs). converters. The high current output stage of the part al ows it to The AD8475 comes with two standard pin-selectable gain drive the switched capacitor front-end circuits of many ADCs with options: 0.4 and 0.8. The gain of the part is set by driving the minimal error. input pin corresponding to the appropriate gain. Unlike many differential drivers in the market, the AD8475 is a The AD8475 also provides overvoltage protection from large high precision amplifier. With 500 µV maximum output offset, industrial input voltages up to ±15 V while operating on a single 10 nV/√Hz output noise, and −112 dB THD + N, the AD8475 5 V supply. The VOCM pin adjusts the output voltage common pairs wel with high accuracy converters. Considering its low power mode for precision level shifting, to match the ADC’s input range consumption and high precision, the slew-enhanced AD8475 has and maximize dynamic range. excellent speed, settling to 18-bit precision for 4 MSPS acquisition. The AD8475 is available in a space-saving 16-lead 3 mm × 3 mm LFCSP package and a 10-lead MSOP package. It is ful y specified over the −40°C to +85°C temperature range.
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAMS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TERMINOLOGY THEORY OF OPERATION OVERVIEW CIRCUIT INFORMATION Output Common-Mode Voltage (VOCM) DC PRECISION INPUT VOLTAGE RANGE DRIVING THE AD8475 POWER SUPPLIES APPLICATIONS INFORMATION TYPICAL CONFIGURATION SINGLE-ENDED TO DIFFERENTIAL CONVERSION SETTING THE OUTPUT COMMON-MODE VOLTAGE HIGH PERFORMANCE ADC DRIVING AD8475 EVALUATION BOARD OUTLINE DIMENSIONS ORDERING GUIDE