ADR435BRZ Analog Devices Inc, ADR435BRZ Datasheet - Page 19

• Manufacturer Part Number: ADR435BRZ
• Description: IC VOLT REF XFET 5.0V 8-SOIC
• Manufacturer: Analog Devices Inc
• Series: XFET®r

Specifications of ADR435BRZ

• Temperature Coefficient: 3ppm/°C
• Design Resources: Converting a Single-Ended Signal with AD7982 Differential PulSAR ADC (CN0032) Converting a Single-Ended Signal with AD7984 Differential PulSAR ADC (CN0033) Parametric Measurement Unit and Supporting Components for PAD Appls Using AD5522 and AD7685 (CN0104) Automated Calibration Technique That Reduces AD5360 Offset Voltage to Less Than 1 mV (CN0123) Integrated Device Power Supply for PAD with Output Voltage Range 0 V to 25 V (CN0130) 16 Channels of Programmable Output Span Using AD5360 (CN0131) 40 Channels of Programmable Output Span Using AD5371 (CN0149) Precision Single-Supply Differential ADC Driver for Industrial-Level Signals (CN0180)
• Reference Type: Series
• Voltage - Output: 5V
• Tolerance: ±0.04%
• Voltage - Input: 7 ~ 18 V
• Number Of Channels: 1
• Current - Quiescent: 800µA
• Current - Output: 30mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Topology: Series
• Input Voltage: 7V To 18V
• Reference Voltage: 5V
• Reference Voltage Tolerance: 2mV
• Voltage Reference Case Style: SOIC
• No. Of Pins: 8
• Fixed / Adjust / Prog: Precision
• Output Voltage (max): 5V
• Reference Voltage Accuracy (max): 0.04
• Line Regulation: 20ppm/V
• Load Regulation: 15ppm/mA
• Input Voltage (max): 20V
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC N
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Cathode: -
• Lead Free Status / Rohs Status: Compliant

PROGRAMMABLE CURRENT SOURCE
Together with a digital potentiometer and a Howland current
pump, the ADR435 forms the reference source for a programmable
current as
and
where:
D is the decimal equivalent of the input code.
N is the number of bits.
In addition, R1' and R2' must be equal to R1 and (R2
respectively. In theory, R2
achieve the necessary current within the A2 output current
driving capability. In this example, the
maximum output current of 10 mA. Because the current pump
employs both positive and negative feedback, C1 and C2
capacitors are needed to ensure that the negative feedback
prevails and, therefore, avoids oscillation. This circuit also
allows bidirectional current flow if the V
the digital potentiometer are supplied with the dual polarity
references, as shown in Figure 41.
V
GND
V
ADR435
DD
2
IN
4
V
U1
I
L
W
TRIM
V
OUT
=
=






2
5
R2
6
D
N
A
×
Figure 41. Programmable Current Source
R
R1
AD5232
V
+
2
A
B
B
REF
U2
R
2
W
B






×
B
V
V
V
OP2177
V+
V–
can be made as small as needed to
DD
SS
W
A1
OP2177
50kΩ
10pF
50kΩ
R1'
C2
A
R1
and V
can deliver a
B
VL
V
V
OP2177
+
–
V–
V+
inputs of
DD
SS
10pF
1kΩ
R2'
A2
C1
R2
1kΩ
A
+ R2
A
ADR430/ADR431/ADR433/ADR434/ADR435/ADR439
B
I
L
),
Rev. H | Page 19 of 24
R2
10Ω
(4)
(5)
B
I
L
PROGRAMMABLE DAC REFERENCE VOLTAGE
By employing a multichannel DAC, such as the AD7398,
quad, 12-bit voltage output DAC, one of its internal DACs
and an ADR43x voltage reference can be used as a common
programmable V
configuration is shown in Figure 42.
The relationship of V
and the ratio of R1 and R2, given by
where:
D is the decimal equivalent of the input code.
N is the number of bits.
V
V
Table 10. V
R1, R2
R1 = R2
R1 = R2
R1 = R2
R1 = 3R2
R1 = 3R2
R1 = 3R2
REF
REFX
is the applied external reference.
V
is the reference voltage for DAC A to DAC D.
REFX
DAC A
DAC B
DAC C
DAC D
V
V
V
V
REFA
REFB
REFC
REFD
=
REFX
V



Figure 42. Programmable DAC Reference
REF
1
vs. R1 and R2
+
REFX
AD7398
2
×
D
Digital Code
0000 0000 0000
1000 0000 0000
1111 1111 1111
0000 0000 0000
1000 0000 0000
1111 1111 1111
N
 +


for the rest of the DACs. The circuit
REFX
1
×
R2
R1
R2
R1
to V






REF
V
V
V
V
OUTA
OUTB
OUTC
OUTD
depends on the digital code
V
R1 ± 0.1%
IN
V
V
V
ADR43x
OC
OD
OB
= V
= V
= V
R2
± 0.1%
V
REFX
REFX
REFX
REF
V
2 V
1.3 V
V
4 V
1.6 V
V
REF
REF
REF
(D
(D
(D
REF
REF
C
D
B
)
)
REF
REF
)
(6)