AD ADR127AUJZ

Precision, Micropower LDO Voltage
References in TSOT
ADR121/ADR125/ADR127
Initial accuracy
A grade: ±0.24%
B grade: ±0.12%
Maximum tempco
A grade: 25 ppm/°C
B grade: 9 ppm/°C
Low dropout: 300 mV for ADR121, ADR125
High output current: +5 mA/−2 mA
Low typical operating current: 85 μA
Input range: 2.7 V to 18 V
Temperature range: −40°C to +125°C
Tiny TSOT (UJ-6) package
PIN CONFIGURATION
NC1 1
6
NC1
ADR12x
5 NC1
TOP VIEW
(Not to Scale)
VIN 3
4 VOUT
GND 2
NC = NO CONNECT
1 MUST BE LEFT FLOATING
05725-001
FEATURES
Figure 1.
APPLICATIONS
Battery-powered instrumentation
Portable medical equipment
Data acquisition systems
Automotive
GENERAL DESCRIPTION
The ADR121/ADR125/ADR127 are a family of micropower,
high precision, series mode, band gap references with sink and
source capability. The parts feature high accuracy and low
power consumption in a tiny package. The ADR12x design
includes a patented temperature drift curvature correction
technique that minimizes the nonlinearities in the output
voltage vs. temperature characteristics.
The ADR12x is a low dropout voltage reference, requiring only
300 mV for ADR121/ADR125 and 1.45 V for ADR127 above
the nominal output voltage on the input to provide a stable
output voltage. This low dropout performance coupled with the
low 85 μA operating current makes the ADR12x ideal for
battery-powered applications.
Available in an extended industrial temperature range of −40°C
to +125°C, the ADR12x is housed in the tiny TSOT (UJ-6)
package.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2006 Analog Devices, Inc. All rights reserved.
ADR121/ADR125/ADR127
TABLE OF CONTENTS
Features .............................................................................................. 1
Terminology .......................................................................................7
Applications....................................................................................... 1
Typical Performance Characteristics ..............................................8
Pin Configuration............................................................................. 1
Theory of Operation ...................................................................... 16
General Description ......................................................................... 1
Power Dissipation Considerations........................................... 16
Revision History ............................................................................... 2
Notes ............................................................................................ 16
Specifications..................................................................................... 3
Applications..................................................................................... 17
ADR121 Electrical Characteristics............................................. 3
Basic Voltage Reference Connection ....................................... 17
ADR125 Electrical Characteristics............................................. 4
Stacking Reference ICs for Arbitrary Outputs ....................... 17
ADR127 Electrical Characteristics............................................. 5
Negative Precision Reference Without Precision Resistors.. 17
Absolute Maximum Ratings............................................................ 6
General-Purpose Current Source ............................................ 17
Thermal Resistance ...................................................................... 6
Outline Dimensions ....................................................................... 18
ESD Caution.................................................................................. 6
Ordering Guide .......................................................................... 18
REVISION HISTORY
6/06—Revision 0: Initial Version
Rev. 0 | Page 2 of 20
ADR121/ADR125/ADR127
SPECIFICATIONS
ADR121 ELECTRICAL CHARACTERISTICS
@ TA = 25°C, VIN = 2.8 V to 18 V, IOUT = 0 mA, unless otherwise noted.
Table 1.
Parameter
OUTPUT VOLTAGE
B Grade
A Grade
INITIAL ACCURACY ERROR
B Grade
A Grade
TEMPERATURE COEFFICIENT
B Grade
A Grade
DROPOUT (VOUT − VIN)
LOAD REGULATION
Symbol
VO
VOERR
TCVO
VDO
PSRR
RIPPLE REJECTION
ΔVOUT/ΔVIN
QUIESCENT CURRENT
IQ
VOLTAGE NOISE
TURN-ON SETTLING TIME
LONG-TERM STABILITY
OUTPUT VOLTAGE HYSTERESIS
Min
Typ
Max
Unit
2.497
2.494
2.5
2.5
2.503
2.506
V
V
+0.12
+0.24
%
%
3
15
9
25
ppm/°C
ppm/°C
mV
80
300
ppm/mA
50
300
ppm/mA
+3
−90
60
+50
ppm/V
dB
dB
95
80
18
40
125
95
μA
μA
mA
mA
@ 25°C
−0.12
−0.24
LINE REGULATION
SHORT-CIRCUIT CURRENT TO GROUND
Conditions/Comments
@ 25°C
−40°C < TA < +125°C
IOUT = 0 mA
−40°C < TA < +125°C; VIN = 3.0 V,
0 mA < IOUT < 5 mA
−40°C < TA < +125°C; VIN = 3.0 V,
−2 mA < IOUT < 0 mA
2.8 V to 18 V
IOUT = 0 mA
f = 1 Khz
f = 60 Hz
−40°C < TA < +125°C, no load
VIN = 18 V
VIN = 2.8 V
VIN = 2.8 V
VIN = 18 V
@ 25°C
f = 10 KHz
0.1 Hz to 10 Hz
To 0.1%, CL = 0.2 μF
1000 hours @ 25°C
See the Terminology section
Rev. 0 | Page 3 of 20
300
−50
500
10
100
150
300
nV/√Hz
μV p-p
μs
ppm/1000 hrs
ppm
ADR121/ADR125/ADR127
ADR125 ELECTRICAL CHARACTERISTICS
@ TA = 25°C, VIN = 5.3 V to 18 V, IOUT = 0 mA, unless otherwise noted.
Table 2.
Parameter
OUTPUT VOLTAGE
B Grade
A Grade
INITIAL ACCURACY ERROR
B Grade
A Grade
TEMPERATURE COEFFICIENT
B Grade
A Grade
DROPOUT (VOUT − VIN)
LOAD REGULATION
Symbol
VO
Condition
@ 25°C
VOERR
2.497
@ 25°C
TCVO
VDO
PSRR
IOUT = 5 mA
−40°C < TA < +125°C; VIN = 3.0 V,
0 mA < IOUT < 5 mA
−40°C < TA < +125°C; VIN = 3.0 V,
−2 mA < IOUT < 0 mA
5.3 V < VIN < 18 V
IOUT = 0 mA
f = 60 Hz
ΔVOUT/ΔVIN
f = 60 Hz
QUIESCENT CURRENT
IQ
−40°C < TA < +125°C, no load
VIN = 18 V
VIN = 3.0 V
VIN = 5.3 V
VIN = 18 V
@ 25°C
f = 10 Khz
0.1 Hz to 10 Hz
To 0.1%, CL = 0.2 μF
1000 hours @ 25°C
See the Terminology section
TURN-ON SETTLING TIME
LONG-TERM STABILITY
OUTPUT VOLTAGE HYSTERESIS
Max
Unit
4.994
4.988
5.0
5.0
5.006
5.012
V
V
+0.12
+0.24
%
%
3
15
9
25
ppm/°C
ppm/°C
mV
35
200
ppm/mA
35
200
ppm/mA
30
−90
ppm/V
dB
60
dB
−40°C < TA < +125°C
RIPPLE REJECTION
VOLTAGE NOISE
Typ
−0.12
−0.24
LINE REGULATION
SHORT-CIRCUIT CURRENT TO GROUND
Min
Rev. 0 | Page 4 of 20
300
95
80
25
40
900
20
100
150
300
125
95
μA
μA
mA
mA
nV/√Hz
μV p-p
μs
ppm/1000 hrs
ppm
ADR121/ADR125/ADR127
ADR127 ELECTRICAL CHARACTERISTICS
@ TA = 25°C, 2.7 V to 18 V, IOUT = 0 mA, unless otherwise noted.
Table 3.
Parameter
OUTPUT VOLTAGE
B Grade
A Grade
INITIAL ACCURACY ERROR
B Grade
A Grade
TEMPERATURE COEFFICIENT
B Grade
A Grade
DROPOUT (VOUT − VIN)
LOAD REGULATION
Symbol
VO
VOERR
Condition
@ 25°C
TCVO
VDO
PSRR
Unit
1.2485
1.2470
1.25
1.25
1.2515
1.2530
V
V
+0.12
+0.24
%
%
3
15
9
25
ppm/°C
ppm/°C
V
85
400
ppm/mA
65
400
ppm/mA
30
−90
90
ppm/V
dB
−40°C < TA < +125°C
IOUT = 0 mA
−40°C < TA < +125°C; VIN = 3.0 V,
0 mA < IOUT < 5 mA
−40°C < TA < +125°C; VIN = 3.0 V,
−2 mA < IOUT < 0 mA
2.7 V to 18 V
IOUT = 0 mA
F = 60 Hz
ΔVOUT/ΔVIN
f = 60 Hz
QUIENSCENT CURRENT
IQ
−40°C < TA < +125°C, no load
VIN = 18 V
VIN = 2.7 V
VIN = 2.7 V
VIN = 18 V
@ 25°C
f = 10 kHz
0.1 Hz to 10 Hz
To 0.1%, CL = 0.2 μF
1000 hours @ 25°C
See the Terminology section
TURN-ON SETTLING TIME
LONG-TERM STABILITY
OUTPUT VOLTAGE HYSTERESIS
Max
@ 25°C
RIPPLE REJECTION
VOLTAGE NOISE
Noise Density
Typ
−0.12
−0.24
LINE REGULATION
SHORT-CIRCUIT CURRENT TO GROUND
Min
Rev. 0 | Page 5 of 20
1.45
60
95
80
15
30
300
5
80
150
300
dB
125
95
μA
μA
mA
mA
nV/√Hz
μV p-p
μs
ppm/1000 hrs
ppm
ADR121/ADR125/ADR127
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter
VIN to GND
Internal Power Dissipation
TSOT (UJ-6)
Storage Temperature Range
Specified Temperature Range
Lead Temperature, Soldering
Vapor Phase (60 sec)
Infrared (15 sec)
Ratings
20 V
40 mW
−65°C to +150°C
−40°C to +125°C
215°C
220°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 5. Thermal Resistance
Package Type
TSOT (UJ-6)
θJA
230
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Rev. 0 | Page 6 of 20
θJC
146
Unit
°C/W
ADR121/ADR125/ADR127
TERMINOLOGY
Temperature Coefficient
The change of output voltage with respect to operating
temperature change normalized by the output voltage at 25°C.
This parameter is expressed in ppm/°C and can be determined
by
TCVO [ppm/°C ] =
VO (T2 ) − VO (T1 )
VO (25°C ) × (T2 − T1 )
× 10
Long-Term Stability
Typical shift of output voltage at 25°C on a sample of parts
subjected to a test of 1000 hours at 25°C.
ΔVO = VO (t O ) − VO (t1 )
ΔVO [ppm ] =
6
VO (t O ) − VO (t1 )
VO (t O )
× 10 6
where:
where:
VO(t0) = VO at 25°C at Time 0.
VO(t1) = VO at 25°C after 1000 hours operating at 25°C.
VO(25°C) = VO at 25°C.
VO(T1) = VO at Temperature 1.
VO(T2) = VO at Temperature 2.
Line Regulation
The change in the output due to a specified change in input
voltage. This parameter accounts for the effects of self-heating.
Line regulation is expressed in either percent per volt, partsper-million per volt, or microvolts per voltage changes in input
voltage.
Load Regulation
The change in output voltage due to a specified change in load
current. This parameter accounts for the effects of self-heating.
Load regulation is expressed in either microvolts per milliampere, parts-per-million per milliampere, or ohms of dc output
resistance.
Thermal Hysteresis
The change of output voltage after the device is cycled through
temperatures from +25°C to −40°C to +125°C and back to
+25°C. This is a typical value from a sample of parts put
through such a cycle.
where:
VO (25°C) = VO at 25°C.
VOTC = VO at 25°C after temperature cycle at +25°C to −40°C to
+125°C and back to +25°C.
Rev. 0 | Page 7 of 20
ADR121/ADR125/ADR127
TYPICAL PERFORMANCE CHARACTERISTICS
1.256
5
1.254
NUMBER OF PARTS
4
1.250
1.248
2
5
20
35
50
65
80
95
110
125
TEMPERATURE (°C)
0
–50
–40
–30
–20
–10
0
10
20
30
40
50
40
50
05725-010
–10
05725-006
–25
40
50
TEMPERATURE COEFFICIENT (ppm/°C)
Figure 2. ADR127 VOUT vs. Temperature
05725-009
1
1.246
1.244
–40
3
05725-011
VOUT (V)
1.252
Figure 5. ADR127 Temperature Coefficient
2.510
5
2.508
2.506
4
NUMBER OF PARTS
VOUT (V)
2.504
2.502
2.500
2.498
2.496
2.494
3
2
1
2.492
–25
–10
5
20
35
50
65
80
95
110
125
TEMPERATURE (°C)
0
–50
05725-007
2.490
–40
–40
–30
–20
–10
0
10
20
30
TEMPERATURE COEFFICIENT (ppm/°C)
Figure 3. ADR121 VOUT vs. Temperature
Figure 6. ADR125 Temperature Coefficient
5.020
5
5.015
4
NUMBER OF PARTS
5.010
5.000
4.995
3
2
4.990
1
4.985
4.980
–40
–25
–10
5
20
35
50
65
80
TEMPERATURE (°C)
95
110
125
05725-008
VOUT (V)
5.005
Figure 4. ADR125 VOUT vs. Temperature
0
–50
–40
–30
–20
–10
0
10
20
30
TEMPERATURE COEFFICIENT (ppm/°C)
Figure 7. ADR121 Temperature Coefficient
Rev. 0 | Page 8 of 20
ADR121/ADR125/ADR127
3.0
120
100
SUPPLY CURRENT (µA)
2.8
2.6
+25°C
2.4
+125°C
2.2
+125°C
–40°C
60
40
–1
0
1
2
3
4
5
LOAD CURRENT (mA)
0
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18
INPUT VOLTAGE (V)
Figure 8. ADR127 Minimum Input Voltage vs. Load Current
05725-015
2.0
–2
+25°C
80
20
05725-012
VIN_MIN (V)
–40°C
Figure 11. ADR127 Supply Current vs. Input Voltage
120
3.5
3.4
SUPPLY CURRENT (µA)
3.2
VIN_MIN (V)
+125°C
100
3.3
+125°C
3.1
+25°C
3.0
–40°C
2.9
2.8
2.7
+25°C
80
–40°C
60
40
20
–1
0
1
2
3
4
5
LOAD CURRENT (mA)
0
05725-013
2
6.0
100
SUPPLY CURRENT (µA)
120
+125°C
5.8
+25°C
–40°C
5.4
6
7
8
9
10 11 12 13 14 15 16 17 18
+25°C
80
+125°C
–40°C
60
40
20
5.2
–1
0
1
2
3
4
5
LOAD CURRENT (mA)
0
05725-014
VIN_MIN (V)
5
Figure 12. ADR121 Supply Current vs. Input Voltage
6.2
5.0
–2
4
INPUT VOLTAGE (V)
Figure 9. ADR121 Minimum Input Voltage vs. Load Current
5.6
3
5
6
7
8
9
10
11
12
13
14
15
16
17
INPUT VOLTAGE (V)
Figure 13. ADR125 Supply Current vs. Input Voltage
Figure 10. ADR125 Minimum Input Voltage vs. Load Current
Rev. 0 | Page 9 of 20
18
05725-017
2.5
–2
05725-016
2.6
ADR121/ADR125/ADR127
6
0
— +125°C
— +25°C
— –40°C
LINE REGULATION (ppm/V)
4
3
2
–10
–20
VIN = 2.7V TO 18V
–30
0
1
2
3
4
5
LOAD CURRENT (mA)
–50
–40
LINE REGULATION (ppm/V)
SUPPLY CURRENT (mA)
35
50
65
80
95
110
125
125
125
2
3
2
1
1
0
VIN = 2.8V TO 18V
–1
–2
–1
0
1
2
3
4
5
LOAD CURRENT (mA)
–3
–40
05725-019
0
–2
–25
–10
5
20
35
50
65
80
95
110
TEMPERATURE (°C)
Figure 15. ADR121 Supply Current vs. Load Current
Figure 18. ADR121 Line Regulation vs. Temperature
6
— +125°C
— +25°C
— –40°C
5
LINE REGULATION (ppm/V)
4
4
3
2
1
2
VIN = 5.3V TO 18V
0
–2
–4
–1
0
1
2
3
4
LOAD CURRENT (mA)
5
05725-020
SUPPLY CURRENT (mA)
20
3
— +125°C
— +25°C
— –40°C
4
0
–2
5
Figure 17. ADR127 Line Regulation vs. Temperature
5
6
-10
TEMPERATURE (°C)
Figure 14. ADR127 Supply Current vs. Load Current
6
-25
05725-021
–1
05725-018
0
–2
05725-022
–40
1
05725-023
SUPPLY CURRENT (mA)
5
Figure 16. ADR125 Supply Current vs. Load Current
–6
–40
–25
–10
5
20
35
50
65
80
95
110
TEMPERATURE (°C)
Figure 19. ADR125 Line Regulation vs. Temperature
Rev. 0 | Page 10 of 20
ADR121/ADR125/ADR127
200
LOAD REGULATION (ppm/mA)
150
CIN = COUT = 0.1µF
2mA SINKING, VIN = 3V
100
50
CH1 p-p
5.76µV
0
1
–50
–100
CH1 rms
0.862µV
5mA SOURCING, VIN = 3V
–150
2µV/DIV
–10
5
20
35
50
65
80
95
110
125
TEMPERATURE (°C)
TIME (1s/DIV)
05725-027
–25
05725-024
–200
–40
Figure 20. ADR127 Load Regulation vs. Temperature
Figure 23. ADR127 0.1 Hz to 10 Hz Noise
100
LOAD REGULATION (ppm/mA)
80
CIN = COUT = 0.1µF
60
2mA SINKING, VIN = 5V
40
20
CH1 p-p
10.8µV
0
–20
1
5mA SOURCING, VIN = 5V
–40
CH1 rms
1.75µV
–60
–80
–10
5
20
35
50
65
80
95
110
125
TEMPERATURE (°C)
TIME (1s/DIV)
05725-025
–25
05725-028
5µV/DIV
–100
–40
Figure 24. ADR121 0.1 Hz to 10 Hz Noise
Figure 21. ADR121 Load Regulation vs. Temperature
50
CIN = COUT = 0.1µF
30
2mA SINKING, VIN = 6V
20
10
CH1 p-p
20.6µV
0
–10
1
CH1 rms
3.34µV
5mA SOURCING, VIN = 6V
–20
–30
–40
–25
–10
5
20
35
50
65
80
95
110
TEMPERATURE (°C)
125
TIME (1s/DIV)
05725-029
10µV/DIV
–50
–40
05725-026
LOAD REGULATION (ppm/mA)
40
Figure 22. ADR125 Load Regulation vs. Temperature
Figure 25. ADR125 0.1 Hz to 10 Hz Noise
Rev. 0 | Page 11 of 20
ADR121/ADR125/ADR127
CIN = COUT = 0.1µF
VIN 1V/DIV
CIN = COUT = 0.1µF
CH1 p-p
287µV
CH1 rms
38.8µV
TIME (1s/DIV)
2
05725-030
50µV/DIV
1
Figure 26. ADR127 10 Hz to 10 KHz Noise
VOUT
500mV/DIV
TIME (200µs/DIV)
05725-033
1
Figure 29. ADR127 Turn-On Response
CIN = COUT = 0.1µF
VIN 1V/DIV
CIN = COUT = 0.1µF
CH1 p-p
450µV
1
CH1 rms
58.1µV
1
VOUT
500mV/DIV
TIME (40µs/DIV)
TIME (1s/DIV)
Figure 27. ADR121 10 Hz to 10 KHz Noise
05725-034
2
05725-031
100µV/DIV
Figure 30. ADR127 Turn-On Response
CIN = COUT = 0.1µF
VIN 1V/DIV
CIN = COUT = 0.1µF
1
1
2
TIME (1s/DIV)
Figure 28. ADR125 10 Hz to 10 KHz Noise
VOUT
500mV/DIV
TIME (100µs/DIV)
Figure 31. ADR127 Turn-Off Response
Rev. 0 | Page 12 of 20
05725-035
200µV/DIV
CH1 rms
115µV
05725-032
CH1 p-p
788µV
ADR121/ADR125/ADR127
CIN = COUT = 0.1µF
VIN 1V/DIV
CIN = COUT = 0.1µF
VIN
2V/DIV
1
1
2
05725-036
TIME (100µs/DIV)
2
TIME (100µs/DIV)
Figure 32. ADR121 Turn-On Response
05725-039
VOUT
2V/DIV
VOUT
1V/DIV
Figure 35. ADR125 Turn-On Response
CIN = COUT = 0.1µF
VIN 1V/DIV
CIN = COUT = 0.1µF
VIN
2V/DIV
1
1
VOUT
2V/DIV
TIME (40µs/DIV)
TIME (20µs/DIV)
2
05725-037
2
Figure 33. ADR121 Turn-On Response
05725-040
VOUT
1V/DIV
Figure 36. ADR125 Turn-On Response
CIN = COUT = 0.1µF
VIN
1V/DIV
VIN
2V/DIV
1
1
VOUT
1V/DIV
2
TIME (20µs/DIV)
Figure 34. ADR121 Turn-Off Response
Figure 37. ADR125 Turn-Off Response
Rev. 0 | Page 13 of 20
05725-041
TIME (200µs/DIV)
05725-038
2
VOUT
2V/DIV
ADR121/ADR125/ADR127
CIN = COUT = 0.1µF
2.50V
1
VIN 1V/DIV
LINE INTERRUPTION
VIN 500mV/DIV
CIN = COUT = 0.1µF
625Ω LOAD
2mA SINKING
1.25V
2
1
TIME (200µs/DIV)
VOUT
20mV/DIV
TIME (40µs/DIV)
05725-045
VOUT
500mV/DIV
05725-042
2
Figure 38. ADR127 Line Transient Response
Figure 41. ADR127 Load Transient Response (Sinking)
CIN = COUT = 0.1µF
1
LINE INTERRUPTION
1V/DIV
1.25V
VIN 500mV/DIV
CIN = COUT = 0.1µF
250Ω LOAD
5mA SOURCING
0V
1
TIME (400µs/DIV)
2
VOUT
100mV/DIV
05725-043
VOUT
500mV/DIV
Figure 39. ADR121 Line Transient Response
TIME (40µs/DIV)
Figure 42. ADR127 Load Transient Response (Sourcing)
CIN = COUT = 0.1µF
1
05725-046
2
5V
VIN 1V/DIV
CIN = COUT = 0.1µF
1250Ω LOAD
2mA SINKING
VIN
1V/DIV
2.5V
1
TIME (400µs/DIV)
VOUT
10mV/DIV
05725-044
VOUT
500mV/DIV
Figure 40. ADR125 Line Transient Response
TIME (40µs/DIV)
Figure 43. ADR121 Load Transient Response (Sinking)
Rev. 0 | Page 14 of 20
05725-047
2
2
ADR121/ADR125/ADR127
0
–20
2.5V
VIN 1V/DIV
CIN = COUT = 0.1µF
500Ω LOAD
5mA SOURCING
–60
0V
–80
(dB)
1
–40
1
–100
–120
–140
2
–160
–180
–200
10
100
1k
10k
100k
1M
10M
100M
05725-051
TIME (40µs/DIV)
05725-048
VOUT
100mV/DIV
Figure 47. ADR121/ADR125/ADR127 PSRR
Figure 44. ADR121 Load Transient Response (Sourcing)
50
45
10V
VIN 2V/DIV
CIN = COUT = 0.1µF
2.5kΩ LOAD
2mA SINKING
5V
OUTPUT IMPEDANCE (Ω)
40
1
35
30
ADR127
25
20
ADR121
15
ADR125
10
2
5
10
5V
1
0V
TIME (40µs/DIV)
05725-050
2
VOUT
100mV/DIV
100
1k
FREQUENCY (Hz)
10k
100k
Figure 48. ADR121/ADR125/ADR127 Output Impedance vs. Frequency
Figure 45. ADR125 Load Transient Response (Sinking)
VIN 2V/DIV
CIN = COUT = 0.1µF
1kΩ LOAD
5mA SOURCING
1
0
05725-054
TIME (40µs/DIV)
05725-049
VOUT
20mV/DIV
Figure 46. ADR125 Load Transient Response (Sourcing)
Rev. 0 | Page 15 of 20
ADR121/ADR125/ADR127
THEORY OF OPERATION
The ADR12x band gap references are the high performance
solution for low supply voltage and low power applications. The
uniqueness of these products lies in their architecture.
POWER DISSIPATION CONSIDERATIONS
The ADR12x family is capable of delivering load currents to
5 mA with an input range from 3.0 V to 18 V. When this device
is used in applications with large input voltages, care must be
taken to avoid exceeding the specified maximum power
dissipation or junction temperature, because this could result in
premature device failure.
Use the following formula to calculate a device’s maximum
junction temperature or dissipation:
PD =
TJ − TA
NOTES
Input Capacitor
Input capacitors are not required on the ADR12x. There is no
limit for the value of the capacitor used on the input, but a 1 μF
to 10 μF capacitor on the input improved transient response in
the applications where there is a sudden supply change. An
additional 0.1 μF capacitor in parallel also helps reduce noise
from the supply.
Output Capacitor
The ADR12x requires a small 0.1 μF capacitor for stability.
Additional 0.1 μF to 10 μF capacitance in parallel can improve
load transient response. This acts as a source of stored energy
for a sudden increase in load current. The only parameter
affected with the additional capacitance is turn-on time.
θ JA
where:
TJ is the junction temperature.
TA is the ambient temperature.
PD is the device power dissipation.
θJA is the device package thermal resistance.
Rev. 0 | Page 16 of 20
ADR121/ADR125/ADR127
APPLICATIONS
BASIC VOLTAGE REFERENCE CONNECTION
Table 6. Required Outputs
The circuit in Figure 4 illustrates the basic configuration for the
ADR12x family voltage reference.
U1/U2
ADR127/ADR121
ADR127/ADR125
ADR121/ADR125
NC
NC 6
ADR12x
+
GND
3
VIN
NEGATIVE PRECISION REFERENCE WITHOUT
PRECISION RESISTORS
NC 5
OUTPUT
VOUT 4
+
0.1µF
0.1µF
A negative reference is easily generated by adding an op amp,
A1, and is configured as shown in Figure 51. VOUT1 is at virtual
ground and, therefore, the negative reference can be taken
directly from the output of the op amp. The op amp must be
dual-supply, low offset, and rail-to-rail if the negative supply
voltage is close to the reference output.
05725-002
INPUT
2
Figure 49. Basic Configuration for the ADR12x Family
STACKING REFERENCE ICs FOR ARBITRARY
OUTPUTS
1 NC
Some applications may require two reference voltage sources
that are a combined sum of the standard outputs. Figure 50
shows how this stacked output reference can be implemented.
NC 6
ADR127
2 GND
NC 5
3 VIN
+VDD
1 NC
VOUT 4
NC 6
ADR12x
2 GND
0.1µF
NC 5
+
+
0.1µF
AD8603
–VREF
OUTPUT1
VOUT 4
1kΩ
2
–
V+
3 VIN
VOUT1
3.75 V
6.25 V
7.5 V
V– + 3
0.1µF
05725-055
1
VOUT2
1.25 V
1.25 V
2.5 V
–VDD
Figure 51. Negative Reference
NC 6
GENERAL-PURPOSE CURRENT SOURCE
ADR12x
2 GND
3 VIN
+
0.1µF
OUTPUT2
NC 5
VOUT 4
+
0.1µF
Figure 50. Stacking References with ADR12x
Two reference ICs are used and fed from an unregulated input,
VIN. The outputs of the individual ICs are connected in series,
which provide two output voltages, VOUT1 and VOUT2. VOUT1 is the
terminal voltage of U1, while VOUT2 is the sum of this voltage
and the terminal of U2. U1 and U2 are chosen for the two
voltages that supply the required outputs (see Table 6). For
example, if U1 and U2 are ADR127 and VIN ≥ 3.95 V, VOUT1 is
1.25 V and VOUT2 is 2.5 V.
In low power applications, the need can arise for a precision
current source that can operate on low supply voltages. The
ADR12x can be configured as a precision current source (see
Figure 52). The circuit configuration shown is a floating current
source with a grounded load. The reference’s output voltage is
bootstrapped across RSET, which sets the output current into the
load. With this configuration, circuit precision is maintained for
load currents ranging from the reference’s supply current,
typically 85 μA, to approximately 5 mA.
1 NC
NC 6
ADR12x
NC 5
2 GND
+VDD
3 VIN
VOUT 4
ISY
R1
ISET
P1
RL
Figure 52. ADR12x Trim Configuration
Rev. 0 | Page 17 of 20
05725-005
1 NC
05725-003
INPUT
ADR121/ADR125/ADR127
OUTLINE DIMENSIONS
2.90 BSC
6
5
4
1
2
3
2.80 BSC
1.60 BSC
PIN 1
INDICATOR
0.95 BSC
1.90
BSC
*0.90
0.87
0.84
*1.00 MAX
0.50
0.30
0.10 MAX
0.20
0.08
SEATING
PLANE
8°
4°
0°
0.60
0.45
0.30
*COMPLIANT TO JEDEC STANDARDS MO-193-AA WITH
THE EXCEPTION OF PACKAGE HEIGHT AND THICKNESS.
Figure 53. 6-Lead Thin Small Outline Transistor Package [TSOT]
(UJ-6)
Dimensions shown in millimeters
ORDERING GUIDE
Model
ADR121AUJZREEL7 1
ADR121AUJZR21
ADR121BUJZREEL71
ADR125AUJZREEL71
ADR125AUJZR21
ADR125BUJZREEL71
ADR127AUJZREEL71
ADR127AUJZR21
ADR127BUJZREEL71
1
Output
Voltage
(VO)
Initial
Accuracy
(mV/%)
Temperature
Coefficient
(ppm/°C)
Package
Description
Package
Option
Temperature
Range (°C)
2.5
2.5
0.24
25
6-Lead TSOT
UJ-6
2.5
2.5
0.24
25
6-Lead TSOT
UJ-6
2.5
2.5
0.12
9
6-Lead TSOT
UJ-6
5.0
5.0
0.24
25
6-Lead TSOT
UJ-6
5.0
5.0
0.24
25
6-Lead TSOT
UJ-6
5.0
5.0
0.12
9
6-Lead TSOT
UJ-6
1.25
3
0.24
25
6-Lead TSOT
UJ-6
1.25
3
0.24
25
6-Lead TSOT
UJ-6
1.25
1.5
0.12
9
6-Lead TSOT
UJ-6
−40°C to
+125°C
−40°C to
+125°C
−40°C to
+125°C
−40°C to
+125°C
−40°C to
+125°C
−40°C to
+125°C
−40°C to
+125°C
−40°C to
+125°C
−40°C to
+125°C
Z = Pb-free part.
Rev. 0 | Page 18 of 20
Ordering
Quantity
3000
Branding
250
R0N
3000
R0P
3000
R0Q
250
R0Q
3000
R0R
3000
R0S
250
R0S
3000
R0T
R0N
ADR121/ADR125/ADR127
NOTES
Rev. 0 | Page 19 of 20
ADR121/ADR125/ADR127
NOTES
©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05725-0-6/06(0)
Rev. 0 | Page 20 of 20