ADR01 Analog Devices, Inc., ADR01 Datasheet - Page 15

• Manufacturer Part Number: ADR01
• Description: Ultracompact Precision10 V/5 V/2.5 V/3.0 V Voltage References
• Manufacturer: Analog Devices, Inc.

APPLICATIONS
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 35).
The band gap cell contains two NPN transistors (Q18 and Q19)
that differ in emitter area by 2×. The difference in their V
produces a proportional-to-absolute temperature current
(PTAT) in R14, and, when combined with the V
produces a band gap voltage, V
temperature. With an internal op amp and the feedback
network of R5 and R6, V
and 3.0 V for the ADR01, ADR02, ADR06, and ADR03,
respectively. Precision laser trimming of the resistors and other
proprietary circuit 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
ADR01/ADR02/ADR03/ADR06. It has a stable 1.96 mV/°C
temperature coefficient, such that users can estimate the
temperature change of the device by knowing the voltage
change at the TEMP pin.
APPLYING THE ADR01/ADR02/ADR03/ADR06
The devices can be used without any external components to
achieve the specified performance. Because of the internal op
amp amplifying the band gap cell to 10.0 V/5.0 V/2.5 V/3.0 V,
power supply decoupling helps the transient response of the
ADR01/ADR02/ADR03/ADR06. As a result, a 0.1 μF ceramic
type decoupling capacitor should be applied as close as possible
to the input and output pins of the device. An optional 1 μF to
10 μF bypass capacitor can also be applied at the V
maintain the input under transient disturbance.
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 36, 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
ADR03 can be adjusted from 2.3 V to 2.8 V. Adjustment of the
output does not significantly affect the temperature performance
of the device, provided the temperature coefficients of the resis-
tors are relatively low.
O
is set precisely at 10.0 V, 5.0 V, 2.5 V,
BG
, that is almost constant in
BE
of Q19,
IN
node to
BE
Rev. J | Page 15 of 24
Temperature Monitoring
As described at the end of the Applications 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 V
and the temperature coefficient is approximately 1.96 mV/°C
(see Figure 37). A voltage change of 39.2 mV at the TEMP pin
corresponds to a 20°C change in temperature.
TEMP
R12
Q18
2X
R17
R14
R27
R13
R32
R11
V
D3
IN
V
IN
0.1μF
Figure 35. Simplified Schematic Diagram
Q19
R1
1X
Q1
C1
Figure 36. Optional Trim Adjustment
R24
Q14 Q15
ADR01/ADR02/ADR03/ADR06
Q16
Q12
Figure 34. Basic Configuration
V
TEMP TRIM
R2
ADR01/
ADR02/
ADR03/
ADR06
IN
TEMP
Q3
Q13
Q2
GND
U1
TEMP TRIM
V
V
ADR01/
ADR02/
ADR03/
ADR06
IN
is approximately 550 mV at 25°C,
OUT
R3
C1
GND
U1
Q7
Q4
V
D1
D2
OUT
R41
470kΩ
R1
Q8
Q20
Q17
C2
0.1μF
I1
R42
Q23
R2
1kΩ
pot
10kΩ
V
V
O
V
BG
Q9
O
R5
R6
R4
Q10
R20
GND
V
V
TRIM
IN
O