Datasheet ADR1581 (Analog Devices) - 10

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ADR1581 USING THE ADR1581 WITH 3 V DATA
The ADR1581 is ideal for creating the reference level to use
CONVERTERS
with 12-bit multiplying DACs, such as the AD7943, AD7945, and AD7948. In the single-supply bias mode (see Figure 25), the The ADR1581 low output drift (50 ppm/°C) and compact impedance seen looking into the IOUT2 terminal changes with subminiature SOT-23 package make it ideally suited for today’s DAC code. If the ADR1581 drives IOUT2 and AGND directly, less high performance converters in space-critical applications. than 0.2 LSBs of additional linearity error results. The buffer amp One family of ADCs for which the ADR1581 is well suited is the eliminates linearity degradation resulting from variations in the AD7714-3 and AD7715-3. The AD7714/AD7715 are charge- reference level. balancing (∑-Δ) ADCs with on-chip digital filtering intended for
3.3V
the measurement of wide dynamic range, low frequency signals, such as those representing chemical, physical, or biological
V R
processes.
DD FB
Figure 24 shows the ADR1581 connected to the
C1 IOUT1
AD7714/AD7715 for 3 V operation.
VREF VIN DAC I A1 OUT2 VOUT 3V AGND A1: OP295 28.7kΩ AD7943 AD822 AD7714-3/AD7715-3 OP2283 REF IN(+) RSW 5kΩ (TYP) HIGH DGND ADR1581 IMPEDANCE REF IN(–) >1GΩ CREF (3pF TO 8pF) 3.3V SWITCHING
24 0
29.4kΩ FREQUENCY DEPENDS
2-
A1 ON fCLKIN
67 06
ADR1581
5 Figure 24. Reference Circuit for the AD7714-3/AD7715-3 -02
SIGNAL GROUND
2 67 06 Figure 25. Single-Supply System Rev. 0 | Page 10 of 12 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION PIN CONFIGURATION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION APPLYING THE ADR1581 TEMPERATURE PERFORMANCE VOLTAGE OUTPUT NONLINEARITY VS. TEMPERATURE REVERSE VOLTAGE HYSTERESIS OUTPUT IMPEDANCE VS. FREQUENCY NOISE PERFORMANCE AND REDUCTION TURN-ON TIME TRANSIENT RESPONSE PRECISION MICROPOWER LOW DROPOUT REFERENCE USING THE ADR1581 WITH 3 V DATA CONVERTERS OUTLINE DIMENSIONS ORDERING GUIDE