View ADR121_706830.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

Precision, Micropower LDO Voltage References in TSOT ADR121/ADR125/ADR127
FEATURES
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 A Input range: 2.7 V to 18 V Temperature range: -40C to +125C Tiny TSOT (UJ-6) package
PIN CONFIGURATION
NC1 1
6
NC1
GND 2
5 NC1 TOP VIEW (Not to Scale) VIN 3 4 VOUT
ADR12x
NC = NO CONNECT
1 MUST BE LEFT FLOATING
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 A operating current makes the ADR12x ideal for battery-powered applications. Available in an extended industrial temperature range of -40C to +125C, 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 (c)2006 Analog Devices, Inc. All rights reserved.
05725-001
ADR121/ADR125/ADR127 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 Pin Configuration............................................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 ADR121 Electrical Characteristics............................................. 3 ADR125 Electrical Characteristics............................................. 4 ADR127 Electrical Characteristics............................................. 5 Absolute Maximum Ratings............................................................ 6 Thermal Resistance ...................................................................... 6 ESD Caution.................................................................................. 6 Terminology .......................................................................................7 Typical Performance Characteristics ..............................................8 Theory of Operation ...................................................................... 16 Power Dissipation Considerations........................................... 16 Notes ............................................................................................ 16 Applications..................................................................................... 17 Basic Voltage Reference Connection ....................................... 17 Stacking Reference ICs for Arbitrary Outputs ....................... 17 Negative Precision Reference Without Precision Resistors.. 17 General-Purpose Current Source ............................................ 17 Outline Dimensions ....................................................................... 18 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 = 25C, 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 Conditions/Comments @ 25C Min 2.497 2.494 VOERR @ 25C -0.12 -0.24 TCVO -40C < TA < +125C 3 15 VDO IOUT = 0 mA -40C < TA < +125C; VIN = 3.0 V, 0 mA < IOUT < 5 mA -40C < TA < +125C; VIN = 3.0 V, -2 mA < IOUT < 0 mA 2.8 V to 18 V IOUT = 0 mA f = 1 Khz f = 60 Hz -40C < TA < +125C, no load VIN = 18 V VIN = 2.8 V VIN = 2.8 V VIN = 18 V @ 25C f = 10 KHz 0.1 Hz to 10 Hz To 0.1%, CL = 0.2 F 1000 hours @ 25C See the Terminology section 300 80 50 -50 +3 -90 60 95 80 18 40 500 10 100 150 300 300 300 +50 9 25 ppm/C ppm/C mV ppm/mA ppm/mA ppm/V dB dB A A mA mA nV/Hz V p-p s ppm/1000 hrs ppm +0.12 +0.24 % % Typ 2.5 2.5 Max 2.503 2.506 Unit V V
LINE REGULATION PSRR RIPPLE REJECTION QUIESCENT CURRENT
VOUT/VIN IQ
125 95
SHORT-CIRCUIT CURRENT TO GROUND VOLTAGE NOISE
TURN-ON SETTLING TIME LONG-TERM STABILITY OUTPUT VOLTAGE HYSTERESIS
Rev. 0 | Page 3 of 20
ADR121/ADR125/ADR127
ADR125 ELECTRICAL CHARACTERISTICS
@ TA = 25C, 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 @ 25C 2.497 @ 25C Min 4.994 4.988 -0.12 -0.24 TCVO -40C < TA < +125C 3 15 VDO IOUT = 5 mA -40C < TA < +125C; VIN = 3.0 V, 0 mA < IOUT < 5 mA -40C < TA < +125C; VIN = 3.0 V, -2 mA < IOUT < 0 mA 5.3 V < VIN < 18 V IOUT = 0 mA f = 60 Hz f = 60 Hz -40C < TA < +125C, no load VIN = 18 V VIN = 3.0 V VIN = 5.3 V VIN = 18 V @ 25C f = 10 Khz 0.1 Hz to 10 Hz To 0.1%, CL = 0.2 F 1000 hours @ 25C See the Terminology section 300 35 35 200 200 30 -90 60 95 80 25 40 900 20 100 150 300 125 95 9 25 ppm/C ppm/C mV ppm/mA ppm/mA ppm/V dB dB A A mA mA nV/Hz V p-p s ppm/1000 hrs ppm Typ 5.0 5.0 Max 5.006 5.012 +0.12 +0.24 Unit V V % %
VOERR
LINE REGULATION PSRR RIPPLE REJECTION QUIESCENT CURRENT VOUT/VIN IQ
SHORT-CIRCUIT CURRENT TO GROUND VOLTAGE NOISE
TURN-ON SETTLING TIME LONG-TERM STABILITY OUTPUT VOLTAGE HYSTERESIS
Rev. 0 | Page 4 of 20
ADR121/ADR125/ADR127
ADR127 ELECTRICAL CHARACTERISTICS
@ TA = 25C, 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 Condition @ 25C Min 1.2485 1.2470 VOERR @ 25C -0.12 -0.24 TCVO -40C < TA < +125C 3 15 VDO IOUT = 0 mA -40C < TA < +125C; VIN = 3.0 V, 0 mA < IOUT < 5 mA -40C < TA < +125C; VIN = 3.0 V, -2 mA < IOUT < 0 mA 2.7 V to 18 V IOUT = 0 mA F = 60 Hz f = 60 Hz -40C < TA < +125C, no load VIN = 18 V VIN = 2.7 V VIN = 2.7 V VIN = 18 V @ 25C f = 10 kHz 0.1 Hz to 10 Hz To 0.1%, CL = 0.2 F 1000 hours @ 25C See the Terminology section 1.45 85 65 30 -90 60 95 80 15 30 300 5 80 150 300 125 95 400 400 90 9 25 ppm/C ppm/C V ppm/mA ppm/mA ppm/V dB dB A A mA mA nV/Hz V p-p s ppm/1000 hrs ppm +0.12 +0.24 % % Typ 1.25 1.25 Max 1.2515 1.2530 Unit V V
LINE REGULATION PSRR RIPPLE REJECTION QUIENSCENT CURRENT VOUT/VIN IQ
SHORT-CIRCUIT CURRENT TO GROUND VOLTAGE NOISE Noise Density TURN-ON SETTLING TIME LONG-TERM STABILITY OUTPUT VOLTAGE HYSTERESIS
Rev. 0 | Page 5 of 20
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 -65C to +150C -40C to +125C 215C 220C
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
JA 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) JA 230 JC 146 Unit C/W
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
ADR121/ADR125/ADR127 TERMINOLOGY
Temperature Coefficient The change of output voltage with respect to operating temperature change normalized by the output voltage at 25C. This parameter is expressed in ppm/C and can be determined by Long-Term Stability Typical shift of output voltage at 25C on a sample of parts subjected to a test of 1000 hours at 25C.
VO = VO (t O ) - VO (t1 ) VO [ppm ] = VO (t O ) - VO (t1 ) VO (t O )
TCVO [ppm/C ] =
where:
VO (25C ) x (T2 - T1 )
VO (T2 ) - VO (T1 )
x 10 6
x 10
6
where: VO(t0) = VO at 25C at Time 0. VO(t1) = VO at 25C after 1000 hours operating at 25C. Thermal Hysteresis The change of output voltage after the device is cycled through temperatures from +25C to -40C to +125C and back to +25C. This is a typical value from a sample of parts put through such a cycle. where: VO (25C) = VO at 25C. VOTC = VO at 25C after temperature cycle at +25C to -40C to +125C and back to +25C.
VO(25C) = VO at 25C. 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.
Rev. 0 | Page 7 of 20
ADR121/ADR125/ADR127 TYPICAL PERFORMANCE CHARACTERISTICS
1.256
5
1.254
4
1.252
VOUT (V)
NUMBER OF PARTS
05725-006
3
1.250
2
1.248
1.246
1
-25
-10
5
20
35
50
65
80
95
110
125
-40
-30
-20
-10
0
10
20
30
40
50
TEMPERATURE (C)
TEMPERATURE COEFFICIENT (ppm/C)
Figure 2. ADR127 VOUT vs. Temperature
2.510 2.508 2.506
Figure 5. ADR127 Temperature Coefficient
5
4
VOUT (V)
2.502 2.500 2.498 2.496 2.494 2.492
05725-007
NUMBER OF PARTS
2.504
3
2
1
-25
-10
5
20
35
50
65
80
95
110
125
-40
-30
-20
-10
0
10
20
30
40
50
TEMPERATURE (C)
TEMPERATURE COEFFICIENT (ppm/C)
Figure 3. ADR121 VOUT vs. Temperature
5.020 5.015 5.010 5.005
4 5
Figure 6. ADR125 Temperature Coefficient
NUMBER OF PARTS
VOUT (V)
3
5.000 4.995 4.990
2
1
4.985 4.980 -40
0 -50
-40
-30
-20
-10
0
10
20
30
40
50
TEMPERATURE (C)
TEMPERATURE COEFFICIENT (ppm/C)
Figure 4. ADR125 VOUT vs. Temperature
Figure 7. ADR121 Temperature Coefficient
Rev. 0 | Page 8 of 20
05725-011
-25
-10
5
20
35
50
65
80
95
110
125
05725-008
05725-010
2.490 -40
0 -50
05725-009
1.244 -40
0 -50
ADR121/ADR125/ADR127
3.0 120
2.8
100
SUPPLY CURRENT (A)
-40C
80
+25C +125C
VIN_MIN (V)
2.6 +25C 2.4
60
-40C
40
2.2
+125C
20
05725-012
-1
0
1
2
3
4
5
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
Figure 8. ADR127 Minimum Input Voltage vs. Load Current
3.5 3.4 3.3
Figure 11. ADR127 Supply Current vs. Input Voltage
120
100
+125C +25C
3.2
SUPPLY CURRENT (A)
+125C +25C -40C
80
VIN_MIN (V)
3.1 3.0 2.9 2.8 2.7 2.6
60
-40C
40
20
05725-013
-1
0
1
2
3
4
5
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
Figure 9. ADR121 Minimum Input Voltage vs. Load Current
6.2
Figure 12. ADR121 Supply Current vs. Input Voltage
120
6.0 +125C 5.8
100
SUPPLY CURRENT (A)
80
+25C +125C
VIN_MIN (V)
+25C 5.6 -40C
60
-40C
5.4
40
5.2
20
05725-014
-1
0
1
2
3
4
5
5
6
7
8
9
10
11
12
13
14
15
16
17
18
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
Figure 10. ADR125 Minimum Input Voltage vs. Load Current
Figure 13. ADR125 Supply Current vs. Input Voltage
Rev. 0 | Page 9 of 20
05725-017
5.0 -2
0
05725-016
2.5 -2
0
05725-015
2.0 -2
0
ADR121/ADR125/ADR127
6 -- +125C -- +25C -- -40C 0
5
4
LINE REGULATION (ppm/V)
-10
SUPPLY CURRENT (mA)
-20 VIN = 2.7V TO 18V -30
3
2
1
-40
05725-018
-1
0
1
2
3
4
5
-25
-10
5
20
35
50
65
80
95
110
125
LOAD CURRENT (mA)
TEMPERATURE (C)
Figure 14. ADR127 Supply Current vs. Load Current
6 -- +125C -- +25C -- -40C 3
Figure 17. ADR127 Line Regulation vs. Temperature
5
2
4
LINE REGULATION (ppm/V)
SUPPLY CURRENT (mA)
1
3
0
VIN = 2.8V TO 18V
2
-1
1
-2
-25
-10
5
20
35
50
65
80
95
110
125
LOAD CURRENT (mA)
TEMPERATURE (C)
Figure 15. ADR121 Supply Current vs. Load Current
6 -- +125C -- +25C -- -40C
6
Figure 18. ADR121 Line Regulation vs. Temperature
5
4
4
LINE REGULATION (ppm/V)
SUPPLY CURRENT (mA)
2
VIN = 5.3V TO 18V
3
0
2
-2
1
-4
-25
-10
5
20
35
50
65
80
95
110
125
LOAD CURRENT (mA)
TEMPERATURE (C)
Figure 16. ADR125 Supply Current vs. Load Current
Figure 19. ADR125 Line Regulation vs. Temperature
Rev. 0 | Page 10 of 20
05725-023
-1
0
1
2
3
4
5
05725-020
0 -2
-6 -40
05725-022
-1
0
1
2
3
4
5
05725-019
0 -2
-3 -40
05725-021
0 -2
-50 -40
ADR121/ADR125/ADR127
200 150
CIN = COUT = 0.1F
2mA SINKING, VIN = 3V
LOAD REGULATION (ppm/mA)
100 50 0 -50 -100 -150
CH1 p-p 5.76V
1
CH1 rms 0.862V
5mA SOURCING, VIN = 3V
2V/DIV
-25 -10 5 20 35 50 65 80 95 110 125
05725-024
TIME (1s/DIV)
05725-027
-200 -40
TEMPERATURE (C)
Figure 20. ADR127 Load Regulation vs. Temperature
100 80
Figure 23. ADR127 0.1 Hz to 10 Hz Noise
LOAD REGULATION (ppm/mA)
60 40 20 0 -20 -40 -60 -80 -25 -10 5 20 35 50 65 80 95 110 125
05725-025
CIN = COUT = 0.1F
2mA SINKING, VIN = 5V
CH1 p-p 10.8V
5mA SOURCING, VIN = 5V
1
CH1 rms 1.75V
5V/DIV
TIME (1s/DIV)
05725-028
-100 -40
TEMPERATURE (C)
Figure 21. ADR121 Load Regulation vs. Temperature
50 40
Figure 24. ADR121 0.1 Hz to 10 Hz Noise
LOAD REGULATION (ppm/mA)
30 20 10 0 -10 -20 -30 -40 -25 -10 5 20 35 50 65 80 95 110 125
05725-026
CIN = COUT = 0.1F
2mA SINKING, VIN = 6V
CH1 p-p 20.6V
1
5mA SOURCING, VIN = 6V
CH1 rms 3.34V
10V/DIV
TIME (1s/DIV)
05725-029
-50 -40
TEMPERATURE (C)
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 = 0.1F
VIN 1V/DIV CIN = COUT = 0.1F
CH1 p-p 287V
1
CH1 rms 38.8V
1
05725-030
50V/DIV
TIME (1s/DIV)
TIME (200s/DIV)
Figure 26. ADR127 10 Hz to 10 KHz Noise
CIN = COUT = 0.1F
Figure 29. ADR127 Turn-On Response
VIN 1V/DIV CIN = COUT = 0.1F
CH1 p-p 450V
1
CH1 rms 58.1V
1
VOUT 500mV/DIV
100V/DIV TIME (1s/DIV)
05725-031
TIME (40s/DIV)
05725-034
2
Figure 27. ADR121 10 Hz to 10 KHz Noise
CIN = COUT = 0.1F
Figure 30. ADR127 Turn-On Response
VIN 1V/DIV CIN = COUT = 0.1F
CH1 p-p 788V
1
CH1 rms 115V
1
200V/DIV
TIME (1s/DIV)
05725-032
VOUT 500mV/DIV
TIME (100s/DIV)
Figure 28. ADR125 10 Hz to 10 KHz Noise
Figure 31. ADR127 Turn-Off Response
Rev. 0 | Page 12 of 20
05725-035
2
05725-033
2
VOUT 500mV/DIV
ADR121/ADR125/ADR127
CIN = COUT = 0.1F
VIN 1V/DIV CIN = COUT = 0.1F
VIN 2V/DIV
1
1
VOUT 1V/DIV
VOUT 2V/DIV
05725-036
TIME (100s/DIV)
Figure 32. ADR121 Turn-On Response
Figure 35. ADR125 Turn-On Response
CIN = COUT = 0.1F
VIN 1V/DIV CIN = COUT = 0.1F
VIN 2V/DIV
1
1
VOUT 1V/DIV
2
TIME (40s/DIV)
05725-037
VOUT 2V/DIV
2
TIME (20s/DIV)
05725-040
Figure 33. ADR121 Turn-On Response
Figure 36. ADR125 Turn-On Response
CIN = COUT = 0.1F
VIN 1V/DIV
VIN 2V/DIV
1
1
VOUT 1V/DIV
VOUT 2V/DIV
05725-038
TIME (20s/DIV)
Figure 34. ADR121 Turn-Off Response
Figure 37. ADR125 Turn-Off Response
Rev. 0 | Page 13 of 20
05725-041
2
TIME (200s/DIV)
2
05725-039
2
TIME (100s/DIV)
2
ADR121/ADR125/ADR127
CIN = COUT = 0.1F
2.50V
1
VIN 1V/DIV LINE INTERRUPTION
VIN 500mV/DIV CIN = COUT = 0.1F 625 LOAD 2mA SINKING
1.25V
2
2
1
05725-042
Figure 38. ADR127 Line Transient Response
CIN = COUT = 0.1F LINE INTERRUPTION 1V/DIV
Figure 41. ADR127 Load Transient Response (Sinking)
1
VIN 500mV/DIV CIN = COUT = 0.1F 250 LOAD 5mA SOURCING
1
TIME (400s/DIV)
2 2
05725-043
TIME (40s/DIV)
Figure 39. ADR121 Line Transient Response
CIN = COUT = 0.1F VIN 1V/DIV
Figure 42. ADR127 Load Transient Response (Sourcing)
1
VIN 1V/DIV CIN = COUT = 0.1F 1250 LOAD 2mA SINKING
1 2 2
05725-044
TIME (400s/DIV)
Figure 40. ADR125 Line Transient Response
Figure 43. ADR121 Load Transient Response (Sinking)
Rev. 0 | Page 14 of 20
05725-047
VOUT 500mV/DIV
VOUT 10mV/DIV
TIME (40s/DIV)
05725-046
VOUT 500mV/DIV
VOUT 100mV/DIV
05725-045
VOUT 500mV/DIV
TIME (200s/DIV)
VOUT 20mV/DIV
TIME (40s/DIV)
1.25V
0V
5V
2.5V
ADR121/ADR125/ADR127
0
2.5V VIN 1V/DIV CIN = COUT = 0.1F 500 LOAD 5mA SOURCING
-20 -40 -60
1
0V
(dB)
-80
1
-100 -120 -140
2
-160
05725-048
TIME (40s/DIV)
-200 10 100 1k 10k 100k 1M 10M 100M
Figure 44. ADR121 Load Transient Response (Sourcing)
50
Figure 47. ADR121/ADR125/ADR127 PSRR
10V
OUTPUT IMPEDANCE ()
45 40 35 30 25 20 15 10
ADR125 ADR121 ADR127
VIN 2V/DIV CIN = COUT = 0.1F 2.5k LOAD 2mA SINKING 5V
1 2
10
100
1k FREQUENCY (Hz)
10k
100k
Figure 45. ADR125 Load Transient Response (Sinking)
Figure 48. ADR121/ADR125/ADR127 Output Impedance vs. Frequency
5V VIN 2V/DIV CIN = COUT = 0.1F 1k LOAD 5mA SOURCING
1
0V
2
TIME (40s/DIV)
Figure 46. ADR125 Load Transient Response (Sourcing)
05725-050
VOUT 100mV/DIV
Rev. 0 | Page 15 of 20
05725-054
TIME (40s/DIV)
05725-049
VOUT 20mV/DIV
5 0
1
05725-051
VOUT 100mV/DIV
-180
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.
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 F to 10 F capacitor on the input improved transient response in the applications where there is a sudden supply change. An additional 0.1 F capacitor in parallel also helps reduce noise from the supply. Output Capacitor The ADR12x requires a small 0.1 F capacitor for stability. Additional 0.1 F to 10 F 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.
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 JA
where: TJ is the junction temperature. TA is the ambient temperature. PD is the device power dissipation. JA is the device package thermal resistance.
Rev. 0 | Page 16 of 20
ADR121/ADR125/ADR127 APPLICATIONS
BASIC VOLTAGE REFERENCE CONNECTION
The circuit in Figure 4 illustrates the basic configuration for the ADR12x family voltage reference.
1
Table 6. Required Outputs
U1/U2 ADR127/ADR121 ADR127/ADR125 ADR121/ADR125 VOUT2 1.25 V 1.25 V 2.5 V VOUT1 3.75 V 6.25 V 7.5 V
NC
NC 6
ADR12x
2
GND VIN
NC 5 VOUT 4 + OUTPUT
NEGATIVE PRECISION REFERENCE WITHOUT PRECISION RESISTORS
0.1F
INPUT +
3
Figure 49. Basic Configuration for the ADR12x Family
STACKING REFERENCE ICs FOR ARBITRARY OUTPUTS
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.
05725-002
0.1F
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.
1 NC
NC 6
ADR127
2 GND
NC 5 VOUT 4
+VDD
1 NC
3 VIN
NC 6
0.1F V+ - 2 1k
ADR12x
2 GND
NC 5 VOUT 4 + OUTPUT1
-VREF
3 VIN
AD8603
05725-055
V- + 3 -VDD
+
0.1F
0.1F
Figure 51. Negative Reference
INPUT
1 NC
NC 6 OUTPUT2
ADR12x
2 GND
GENERAL-PURPOSE CURRENT SOURCE
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 A, to approximately 5 mA.
1 NC
NC 5 VOUT 4 +
3 VIN
+
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.
05725-003
0.1F
0.1F
NC 6
ADR12x
2 GND
NC 5 VOUT 4 R1 ISET
+VDD
3 VIN
ISY
P1 RL
Figure 52. ADR12x Trim Configuration
Rev. 0 | Page 17 of 20
05725-005
ADR121/ADR125/ADR127 OUTLINE DIMENSIONS
2.90 BSC
6 5 4
1.60 BSC
1 2 3
2.80 BSC
PIN 1 INDICATOR 0.95 BSC *0.90 0.87 0.84 1.90 BSC
*1.00 MAX
0.20 0.08 8 4 0 0.60 0.45 0.30
0.10 MAX
0.50 0.30
SEATING PLANE
*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) 2.5 2.5 2.5 5.0 5.0 5.0 1.25 1.25 1.25
Initial Accuracy (mV/%) 2.5 2.5 2.5 5.0 5.0 5.0 3 3 1.5 0.24 0.24 0.12 0.24 0.24 0.12 0.24 0.24 0.12
Temperature Coefficient (ppm/C) 25 25 9 25 25 9 25 25 9
Package Description 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT
Package Option UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 UJ-6
Temperature Range (C) -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C
Ordering Quantity 3000 250 3000 3000 250 3000 3000 250 3000
Branding R0N R0N R0P R0Q R0Q R0R R0S R0S R0T
Z = Pb-free part.
Rev. 0 | Page 18 of 20
ADR121/ADR125/ADR127
NOTES
Rev. 0 | Page 19 of 20
ADR121/ADR125/ADR127
NOTES
(c)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

▲Up To Search▲

Price & Availability of ADR121

	To Download ADR121 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .