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ADR02AKS-R2 View Datasheet(PDF) - Analog Devices

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ADR02AKS-R2 Datasheet PDF : 24 Pages
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ADR01/ADR02/ADR03/ADR06
APPLICATIONS INFORMATION
OVERVIEW
ADR03 can be adjusted from 2.3 V to 2.8 V. Adjustment of the
The ADR01/ADR02/ADR03/ADR06 are high precision, low
drift 10.0 V, 5.0 V, 2.5 V, and 3.0 V voltage references available
in an ultracompact footprint. The 8-lead SOIC versions of the
devices are drop-in replacements of the REF01/REF02/REF03
sockets with improved cost and performance.
These devices are standard band gap references (see Figure 34).
The band gap cell contains two NPN transistors (Q18 and Q19)
that differ in emitter area by 2×. The difference in their VBE
produces a proportional-to-absolute temperature current (PTAT)
output does not significantly affect the temperature performance
of the device, provided the temperature coefficients of the resis-
tors are relatively low.
VIN
C1
0.1µF
U1
ADR01/
ADR02/
ADR03/
ADR06
VIN VOUT
TEMP TRIM
GND
VO
C2
0.1µF
in R14, and, when combined with the VBE of Q19, produces a
band gap voltage, VBG, that is almost constant in temperature.
Figure 33. Basic Configuration
With an internal op amp and the feedback network of R5 and
R6, VO is set precisely at 10.0 V, 5.0 V, 2.5 V, and 3.0 V for the
R1
R2
R3
VIN
R4
ADR01, ADR02, ADR06, and ADR03, respectively. Precision
laser trimming of the resistors and other proprietary circuit
Q23
Q1
Q2 Q7
Q8
techniques are used to further enhance the initial accuracy,
temperature curvature, and drift performance of the ADR01/
ADR02/ADR03/ADR06.
The PTAT voltage is made available at the TEMP pin of the
Q3
D1
D2
Q4
Q9
Q10
VO
ADR01/ADR02/ADR03/ADR06. It has a stable 1.96 mV/°C
D3
C1
temperature coefficient, such that users can estimate the
temperature change of the device by knowing the voltage
change at the TEMP pin.
Q13
Q12
R12
R13
Q14 Q15
R5
I1
R20
TRIM
APPLYING THE ADR01/ADR02/ADR03/ADR06
Q18
VBG
Input and Output Capacitors
R27 Q19
Although the ADR01/ADR02/ADR03/ADR06 are designed to
function stably without any external components, connecting a
0.1 μF ceramic capacitor to the output is highly recommended
to improve stability and filter out low level voltage noise. An
TEMP R14
Q16
R32
R24
R17 R11
Q17
Q20
R6
R41
R42
GND
additional 1 μF to 10 μF electrolytic, tantalum, or ceramic
Figure 34. Simplified Schematic Diagram
capacitor can be added in parallel to improve transient per-
formance in response to sudden changes in load current;
however, the designer should keep in mind that doing so
increases the turn-on time of the device.
A 1 μF to 10 μF electrolytic, tantalum or ceramic capacitor can
also be connected to the input to improve transient response in
applications where the supply voltage may fluctuate. An addi-
U1
ADR01/
ADR02/
ADR03/
ADR06
VIN
VIN VOUT
VO
TEMP TRIM
GND
R1
470k
POT
10k
tional 0.1 μF ceramic capacitor should be connected in parallel
R2
1k
to reduce supply noise. Mount both input and output capacitors
as close to the device pins as possible.
Figure 35. Optional Trim Adjustment
Output Adjustment
The ADR01/ADR02/ADR03/ADR06 trim terminal can be used
to adjust the output voltage over a nominal voltage. This feature
allows a system designer to trim system errors by setting the
reference to a voltage other than 10.0 V/5.0 V/2.5 V/3.0 V. For
finer adjustment, add a series resistor of 470 kΩ. With the con-
figuration shown in Figure 35, the ADR01 can be adjusted from
9.70 V to 10.05 V, the ADR02 can be adjusted from 4.95 V to
5.02 V, the ADR06 can be adjusted from 2.8 V to 3.3 V, and the
Temperature Monitoring
As described at the end of the Overview section, the ADR01/
ADR02/ADR03/ADR06 provide a TEMP output (Pin 1 in Figure 1
and Pin 3 in Figure 2) that varies linearly with temperature. This
output can be used to monitor the temperature change in the
system. The voltage at VTEMP is approximately 550 mV at 25°C,
and the temperature coefficient is approximately 1.96 mV/°C
(see Figure 36). A voltage change of 39.2 mV at the TEMP pin
corresponds to a 20°C change in temperature.
Rev. L | Page 14 of 24
 

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