ADR1581 Analog Devices, Inc., ADR1581 Datasheet - Page 10

• Manufacturer Part Number: ADR1581
• Description: 1.25 V Micropower, Precision Shunt Voltage Reference
• Manufacturer: Analog Devices, Inc.

ADR1581
USING THE ADR1581 WITH 3 V DATA
CONVERTERS
The ADR1581 low output drift (50 ppm/°C) and compact
subminiature SOT-23 package make it ideally suited for today’s
high performance converters in space-critical applications.
One family of ADCs for which the ADR1581 is well suited is the
AD7714-3
balancing (∑-Δ) ADCs with on-chip digital filtering intended for
the measurement of wide dynamic range, low frequency signals,
such as those representing chemical, physical, or biological
processes.
AD7714/AD7715 for 3 V operation.
ADR1581
28.7kΩ
Figure 24. Reference Circuit for the AD7714-3/AD7715-3
Figure 24 shows the ADR1581 connected to the
and AD7715-3. The AD7714/AD7715 are charge-
3V
REF IN(+)
REF IN(–)
SWITCHING
FREQUENCY DEPENDS
ON
f
CLKIN
(3pF TO 8pF)
5kΩ (TYP)
R
SW
C
REF
AD7714-3/AD7715-3
IMPEDANCE
>1GΩ
HIGH
Rev. 0 | Page 10 of 12
The ADR1581 is ideal for creating the reference level to use
with 12-bit multiplying DACs, such as the AD7943, AD7945,
and AD7948. In the single-supply bias mode (see Figure 25), the
impedance seen looking into the I
DAC code. If the ADR1581 drives I
than 0.2 LSBs of additional linearity error results. The buffer amp
eliminates linearity degradation resulting from variations in the
reference level.
V
IN
V
REF
ADR1581
29.4kΩ
3.3V
AD7943
V
DGND
Figure 25. Single-Supply System
DD
3.3V
DAC
SIGNAL GROUND
R
FB
A1
I
I
AGND
OUT1
OUT2
OUT2
OUT2
C1
terminal changes with
and AGND directly, less
A1
A1: OP295
AD822
OP2283
V
OUT