Data Sheet
Precision Micropower,
Low Dropout Voltage References
REF19x Series
FEATURES
TEST PINS
Temperature coefficient: 5 ppm/°C maximum
High output current: 30 mA
Low supply current: 45 μA maximum
Initial accuracy: ±2 mV maximum 1
Sleep mode: 15 μA maximum
Low dropout voltage
Load regulation: 4 ppm/mA
Line regulation: 4 ppm/V
Short-circuit protection
Test Pin 1 and Test Pin 5 are reserved for in-package Zener zap.
To achieve the highest level of accuracy at the output, the Zener
zapping technique is used to trim the output voltage. Because
each unit may require a different amount of adjustment, the
resistance value at the test pins varies widely from pin to pin
and from part to part. The user should leave Pin 1 and Pin 5
unconnected.
TP 1
VS 2
REF19x
SERIES
8
NC
7
NC
SLEEP 3
APPLICATIONS
Portable instruments
ADCs and DACs
Smart sensors
Solar powered applications
Loop-current-powered instruments
NOTES
1. NC = NO CONNECT.
2. TP PINS ARE FACTORY TEST
POINTS, NO USER CONNECTION.
Figure 1. 8-Lead SOIC_N and TSSOP Pin Configuration
(S Suffix and RU Suffix)
TP 1
VS 2
GENERAL DESCRIPTION
SLEEP 3
The REF19x series references are specified over the extended
industrial temperature range (−40°C to +85°C) with typical
performance specifications over −40°C to +125°C for
applications, such as automotive.
REF19x
SERIES
8
NC
7
NC
NOTES
1. NC = NO CONNECT.
2. TP PINS ARE FACTORY TEST
POINTS, NO USER CONNECTION.
00371-002
6 OUTPUT
TOP VIEW
GND 4 (Not to Scale) 5 TP
The REF19x series precision band gap voltage references use a
patented temperature drift curvature correction circuit and
laser trimming of highly stable, thin-film resistors to achieve a
very low temperature coefficient and high initial accuracy.
The REF19x series is made up of micropower, low dropout
voltage (LDV) devices, providing stable output voltage from
supplies as low as 100 mV above the output voltage and
consuming less than 45 μA of supply current. In sleep mode,
which is enabled by applying a low TTL or CMOS level to the
SLEEP pin, the output is turned off and supply current is
further reduced to less than 15 μA.
00371-001
6 OUTPUT
TOP VIEW
GND 4 (Not to Scale) 5 TP
Figure 2. 8-Lead PDIP Pin Configuration
(P Suffix)
Table 1. Nominal Output Voltage
Part Number
REF191
REF192
REF193
REF194
REF195
REF196
REF198
Nominal Output Voltage (V)
2.048
2.50
3.00
4.50
5.00
3.30
4.096
All electrical grades are available in an 8-lead SOIC package; the
PDIP and TSSOP packages are available only in the lowest
electrical grade.
1
Initial accuracy does not include shift due to solder heat effect (see the
Applications Information section).
Rev. L
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 ©1996–2011 Analog Devices, Inc. All rights reserved.
REF19x Series
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Electrical Characteristics—REF196 @ −40°C ≤ TA ≤ +125°C
....................................................................................................... 13
General Description ......................................................................... 1
Electrical Characteristics—REF198 @ TA = 25°C.................. 14
Test Pins ............................................................................................. 1
Electrical Characteristics—REF198 @ −40°C ≤ TA ≤ +85°C
....................................................................................................... 14
Revision History ............................................................................... 3
Specifications..................................................................................... 4
Electrical Characteristics—REF191 @ TA = 25°C .................... 4
Electrical Characteristics—REF191 @ −40°C ≤ +85°C........... 5
Electrical Characteristics—REF198 @ −40°C ≤ TA ≤ 125°C15
Absolute Maximum Ratings ......................................................... 16
Thermal Resistance .................................................................... 16
ESD Caution................................................................................ 16
Electrical Characteristics—REF191 @
−40°C ≤ TA ≤ +125°C................................................................... 6
Typical Performance Characteristics ........................................... 17
Electrical Characteristics—REF192 @ TA = 25°C .................... 6
Applications Information .............................................................. 20
Electrical Characteristics—REF192 @ −40°C ≤ TA ≤ +85°C
......................................................................................................... 7
Output Short-Circuit Behavior ................................................ 20
Electrical Characteristics—REF192 @ −40°C ≤ TA ≤ +125°C
......................................................................................................... 7
Output Voltage Bypassing ......................................................... 20
Electrical Characteristics—REF193 @ TA = 25°C .................... 8
Basic Voltage Reference Connections ..................................... 20
Electrical Characteristics—REF193 @ −40°C ≤ TA ≤ +85°C
......................................................................................................... 8
Membrane Switch-Controlled Power Supply............................. 20
Electrical Characteristics—REF193 @ TA ≤ −40°C ≤ +125°C
......................................................................................................... 9
Current-Boosted References with Current Limiting............. 21
Device Power Dissipation Considerations.............................. 20
Sleep Mode Operation............................................................... 20
Solder Hear Effect ...................................................................... 21
Electrical Characteristics—REF194 @ TA = 25°C .................... 9
Negative Precision Reference Without Precision Resistors.. 22
Electrical Characteristics—REF194 @ −40°C ≤ TA ≤ +85°C
....................................................................................................... 10
Stacking Reference ICs for Arbitrary Outputs ....................... 22
Electrical Characteristics—REF194 @ −40°C ≤ TA ≤ +125°C
....................................................................................................... 10
Switched Output 5 V/3.3 V Reference..................................... 23
Electrical Characteristics—REF195 @ TA = 25°C .................. 11
Fail-Safe 5 V Reference.............................................................. 24
Electrical Characteristics—REF195 @ −40°C ≤ TA ≤ +85°C
....................................................................................................... 11
Low Power, Strain Gage Circuit ............................................... 25
Electrical Characteristics—REF195 @ −40°C ≤ TA ≤ +125°C
....................................................................................................... 12
Precision Current Source .......................................................... 23
Kelvin Connections.................................................................... 24
Outline Dimensions ....................................................................... 26
Ordering Guide .......................................................................... 27
Electrical Characteristics—REF196 @ TA = 25°C .................. 12
Electrical Characteristics—REF196 @ −40°C ≤ TA ≤ +85°C
....................................................................................................... 13
Rev. L | Page 2 of 28
Data Sheet
REF19x Series
REVISION HISTORY
9/11—Rev. K to Rev. L
Change to Condition Column for Dropout Voltage Parameter,
Table 2 ................................................................................................. 4
Change to Condition Column for Dropout Voltage Parameter,
Table 3 ................................................................................................. 5
Change to Operating Temperature Range, Table 23...................16
7/10—Rev. J to Rev. K
Add Note 1, Features Section........................................................... 1
Changes to Note 1, Table 2 ............................................................... 4
Changes to Note 1, Table 5 ............................................................... 6
Changes to Note 1, Table 8 ............................................................... 8
Changes to Note 1, Table 11 ............................................................. 9
Changes to Note 1, Table 14 ...........................................................11
Changes to Note 1, Table 17 ...........................................................12
Changes to Note 1, Table 20 ...........................................................14
Moved Figure 22 ..............................................................................20
Added Figure 23, Solder Heat Effect Section, and Figure 24;
Renumbered Sequentially ..............................................................21
Moved Negative Precision Reference Without Precision
Resistors Section ..............................................................................22
Moved Precision Current Source Section ....................................23
Moved Kelvin Connections Section .............................................24
Moved Figure 32 ..............................................................................25
Updated Outline Dimensions ........................................................26
Changes to Ordering Guide ...........................................................27
3/08—Rev. I to Rev. J
Changes to General Description ..................................................... 1
Changes to Specifications Section................................................... 4
Deleted Wafer Test Limits Section ................................................14
Changes to Table 23, Thermal Resistance Section, and
Table 24 .............................................................................................16
Changes to Figure 6.........................................................................17
Changes to Device Power Dissipation
Considerations Section ...................................................................20
Changes to Current-Boosted References with Current
Limiting Section ..............................................................................21
Changes to Precision Current Source Section ............................ 22
Changes to Figure 28 ...................................................................... 23
Changes to Figure 30 ...................................................................... 24
Changes to Low Power, Strain Gage Circuit Section.................. 25
Changes to Ordering Guide ........................................................... 27
9/06—Rev. H to Rev. I
Updated Format ................................................................. Universal
Changes to Table 25 ........................................................................ 16
Changes to Figure 6 ........................................................................ 16
Changes to Figure 10, Figure 12, Figure 14, and Figure 26 ....... 17
Changes to Figure 18 ...................................................................... 18
Changes to Figure 20 ...................................................................... 19
Changes to Figure 23 ...................................................................... 20
Changes to Figure 25 ...................................................................... 21
Updated Outline Dimensions........................................................ 25
Changes to Ordering Guide ........................................................... 26
6/05—Rev. G to Rev. H
Updated Format ................................................................. Universal
Changes to Caption in Figure 7..................................................... 16
Updated Outline Dimensions........................................................ 25
Changes to Ordering Guide ........................................................... 26
7/04—Rev. F to Rev. G
Changes to Ordering Guide ............................................................. 4
3/04—Rev. E to Rev. F
Updated Absolute Maximum Rating.............................................. 4
Changes to Ordering Guide ........................................................... 14
Updated Outline Dimensions........................................................ 24
1/03—Rev. D to Rev. E
Changes to Figure 3 and Figure 4 ................................................. 15
Changes to Output Short Circuit Behavior ................................. 17
Changes to Figure 20 ...................................................................... 17
Changes to Figure 26 ...................................................................... 19
Updated Outline Dimensions........................................................ 23
1/96—Revision 0: Initial Version
Rev. L | Page 3 of 28
REF19x Series
Data Sheet
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS—REF191 @ TA = 25°C
@ VS = 3.3 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter
INITIAL ACCURACY 1
E Grade
F Grade
G Grade
LINE REGULATION 2
E Grade
F and G Grades
LOAD REGULATION2
E Grade
F and G Grades
DROPOUT VOLTAGE
Symbol
VO
LONG-TERM STABILITY 3
NOISE VOLTAGE
DVO
eN
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2.046
2.043
2.038
2.048
2.050
2.053
2.058
V
V
V
3.0 V ≤ VS ≤ 15 V, IOUT = 0 mA
2
4
4
8
ppm/V
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 30 mA
4
6
10
15
0.95
1.25
1.55
ppm/mA
ppm/mA
V
V
V
mV
μV p-p
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 3.0 V, ILOAD = 2 mA
VS = 3.3 V, ILOAD = 10 mA
VS = 3.6 V, ILOAD = 30 mA
1000 hours @ 125°C
0.1 Hz to 10 Hz
1
1.2
20
Initial accuracy does not include shift due to solder heat effect (see the Applications Information section).
Line and load regulation specifications include the effect of self-heating.
3
Long-term stability specification is noncumulative. The drift in subsequent 1000-hour periods is significantly lower than in the first 1000-hour period.
2
Rev. L | Page 4 of 28
Data Sheet
REF19x Series
ELECTRICAL CHARACTERISTICS—REF191 @ −40°C ≤ +85°C
@ VS = 3.3 V, −40°C ≤ TA ≤ +85°C, unless otherwise noted.
Table 3.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
F Grade
G Grade 3
LINE REGULATION 4
E Grade
F and G Grades
LOAD REGULATION4
E Grade
F and G Grades
DROPOUT VOLTAGE
SLEEP PIN
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
SUPPLY CURRENT
Sleep Mode
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2
5
10
5
10
25
ppm/°C
ppm/°C
ppm/°C
3.0 V ≤ VS ≤ 15 V, IOUT = 0 mA
5
10
10
20
ppm/V
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 25 mA
5
10
15
20
0.95
1.25
1.55
ppm/mA
ppm/mA
V
V
V
−8
0.8
−8
45
15
V
μA
V
μA
μA
μA
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 3.0 V, ILOAD = 2 mA
VS = 3.3 V, ILOAD = 10 mA
VS = 3.6 V, ILOAD = 25 mA
VH
IH
VL
IL
2.4
No load
No load
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
Rev. L | Page 5 of 28
REF19x Series
Data Sheet
ELECTRICAL CHARACTERISTICS—REF191 @ −40°C ≤ TA ≤ +125°C
@ VS = 3.3 V, −40°C ≤ TA ≤ +125°C, unless otherwise noted.
Table 4.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
F Grade
G Grade 3
LINE REGULATION 4
E Grade
F and G Grades
LOAD REGULATION4
E Grade
F and G Grades
DROPOUT VOLTAGE
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2
5
10
ppm/°C
ppm/°C
ppm/°C
3.0 V ≤ VS ≤ 15 V, IOUT = 0 mA
10
20
ppm/V
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 20 mA
10
20
ppm/mA
ppm/mA
V
V
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 3.3 V, ILOAD = 10 mA
VS = 3.6 V, ILOAD = 20 mA
1.25
1.55
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
ELECTRICAL CHARACTERISTICS—REF192 @ TA = 25°C
@ VS = 3.3 V, TA = 25°C, unless otherwise noted.
Table 5.
Parameter
INITIAL ACCURACY 1
E Grade
F Grade
G Grade
LINE REGULATION 2
E Grade
F and G Grades
LOAD REGULATION2
E Grade
F and G Grades
DROPOUT VOLTAGE
Symbol
VO
LONG-TERM STABILITY 3
NOISE VOLTAGE
DVO
eN
1
2
3
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2.498
2.495
2.490
2.500
2.502
2.505
2.510
V
V
V
3.0 V ≤ VS ≤ 15 V, IOUT = 0 mA
2
4
4
8
ppm/V
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 30 mA
4
6
10
15
1.00
1.40
ppm/mA
ppm/mA
V
V
mV
μV p-p
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 3.5 V, ILOAD = 10 mA
VS = 3.9 V, ILOAD = 30 mA
1000 hours @ 125°C
0.1 Hz to 10 Hz
1.2
25
Initial accuracy does not include shift due to solder heat effect (see the Applications Information section).
Line and load regulation specifications include the effect of self-heating.
Long-term stability specification is noncumulative. The drift in subsequent 1000-hour periods is significantly lower than in the first 1000-hour period.
Rev. L | Page 6 of 28
Data Sheet
REF19x Series
ELECTRICAL CHARACTERISTICS—REF192 @ −40°C ≤ TA ≤ +85°C
@ VS = 3.3 V, −40°C ≤ TA ≤ +85°C, unless otherwise noted.
Table 6.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
F Grade
G Grade 3
LINE REGULATION 4
E Grade
F and G Grades
LOAD REGULATION4
E Grade
F and G Grades
DROPOUT VOLTAGE
SLEEP PIN
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
SUPPLY CURRENT
Sleep Mode
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2
5
10
5
10
25
ppm/°C
ppm/°C
ppm/°C
3.0 V ≤ VS ≤ 15 V, IOUT = 0 mA
5
10
10
20
ppm/V
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 25 mA
5
10
15
20
1.00
1.50
ppm/mA
ppm/mA
V
V
−8
0.8
−8
45
15
V
μA
V
μA
μA
μA
Max
Unit
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 3.5 V, ILOAD = 10 mA
VS = 4.0 V, ILOAD = 25 mA
VH
IH
VL
IL
2.4
No load
No load
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
ELECTRICAL CHARACTERISTICS—REF192 @ −40°C ≤ TA ≤ +125°C
@ VS = 3.3 V, −40°C ≤ TA ≤ +125°C, unless otherwise noted.
Table 7.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
F Grade
G Grade 3
LINE REGULATION 4
E Grade
F and G Grades
LOAD REGULATION4
E Grade
F and G Grades
DROPOUT VOLTAGE
1
2
Symbol
TCVO/°C
Condition
Min
Typ
IOUT = 0 mA
2
5
10
ppm/°C
ppm/°C
ppm/°C
3.0 V ≤ VS ≤ 15 V, IOUT = 0 mA
10
20
ppm/V
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 20 mA
10
20
ppm/mA
ppm/mA
V
V
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 3.5 V, ILOAD = 10 mA
VS = 4.0 V, ILOAD = 20 mA
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
Rev. L | Page 7 of 28
1.00
1.50
REF19x Series
Data Sheet
ELECTRICAL CHARACTERISTICS—REF193 @ TA = 25°C
@ VS = 3.3 V, TA = 25°C, unless otherwise noted.
Table 8.
Parameter
INITIAL ACCURACY 1
G Grade
LINE REGULATION 2
G Grade
LOAD REGULATION2
G Grade
DROPOUT VOLTAGE
Symbol
VO
LONG-TERM STABILITY 3
NOISE VOLTAGE
DVO
eN
1
2
3
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2.990
3.0
3.010
V
3.3 V, ≤ VS ≤ 15 V, IOUT = 0 mA
4
8
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 30 mA
VS = 3.8 V, ILOAD = 10 mA
VS = 4.0 V, ILOAD = 30 mA
1000 hours @ 125°C
0.1 Hz to 10 Hz
6
15
0.80
1.00
ppm/mA
V
V
mV
μV p-p
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
1.2
30
Initial accuracy does not include shift due to solder heat effect (see the Applications Information section).
Line and load regulation specifications include the effect of self-heating.
Long-term stability specification is noncumulative. The drift in subsequent 1000-hour periods is significantly lower than in the first 1000-hour period.
ELECTRICAL CHARACTERISTICS—REF193 @ −40°C ≤ TA ≤ +85°C
@ VS = 3.3 V, TA = −40°C ≤ TA ≤ +85°C, unless otherwise noted.
Table 9.
Parameter
TEMPERATURE COEFFICIENT 1, 2
G Grade 3
LINE REGULATION 4
G Grade
LOAD REGULATION4
G Grade
DROPOUT VOLTAGE
SLEEP PIN
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
SUPPLY CURRENT
Sleep Mode
1
2
Symbol
TCVO/°C
Condition
Typ
Max
Unit
IOUT = 0 mA
10
25
ppm/°C
3.3 V ≤ VS ≤ 15 V, IOUT = 0 mA
10
20
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 25 mA
VS = 3.8 V, ILOAD = 10 mA
VS = 4.1 V, ILOAD = 30 mA
10
20
0.80
1.10
ppm/mA
V
V
−8
0.8
−8
45
15
V
μA
V
μA
μA
μA
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VH
IH
VL
IL
2.4
No load
No load
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
4
Min
Guaranteed by characterization.
Line and load regulation specifications include the effect of self-heating.
Rev. L | Page 8 of 28
Data Sheet
REF19x Series
ELECTRICAL CHARACTERISTICS—REF193 @ TA ≤ −40°C ≤ +125°C
@ VS = 3.3 V, –40°C ≤ TA ≤ +125°C, unless otherwise noted.
Table 10.
Parameter
TEMPERATURE COEFFICIENT 1, 2
G Grade 3
LINE REGULATION 4
G Grade
LOAD REGULATION4
G Grade
DROPOUT VOLTAGE
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
10
ppm/°C
3.3 V ≤ VS ≤ 15 V, IOUT = 0 mA
20
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 20 mA
VS = 3.8 V, ILOAD = 10 mA
VS = 4.1 V, ILOAD = 20 mA
10
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
0.80
1.10
ppm/mA
V
V
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
ELECTRICAL CHARACTERISTICS—REF194 @ TA = 25°C
@ VS = 5.0 V, TA = 25°C, unless otherwise noted.
Table 11.
Parameter
INITIAL ACCURACY 1
E Grade
G Grade
LINE REGULATION 2
E Grade
G Grade
LOAD REGULATION2
E Grade
G Grade
DROPOUT VOLTAGE
Symbol
VO
LONG-TERM STABILITY 3
NOISE VOLTAGE
DVO
eN
1
2
3
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
4.498
4.490
4.5
4.502
4.510
V
V
4.75 V ≤ VS ≤ 15 V, IOUT = 0 mA
2
4
4
8
ppm/V
ppm/V
VS = 5.8 V, 0 mA ≤ IOUT ≤ 30 mA
2
4
4
8
0.50
1.30
ppm/mA
ppm/mA
V
V
mV
μV p-p
∆VO/∆VIN
∆VO/∆VLOAD
V S − VO
VS = 5.00 V, ILOAD = 10 mA
VS = 5.8 V, ILOAD = 30 mA
1000 hours @ 125°C
0.1 Hz to 10 Hz
2
45
Initial accuracy does not include shift due to solder heat effect (see the Applications Information section).
Line and load regulation specifications include the effect of self-heating.
Long-term stability specification is noncumulative. The drift in subsequent 1000-hour periods is significantly lower than in the first 1000-hour period.
Rev. L | Page 9 of 28
REF19x Series
Data Sheet
ELECTRICAL CHARACTERISTICS—REF194 @ −40°C ≤ TA ≤ +85°C
@ VS = 5.0 V, TA = −40°C ≤ TA ≤ +85°C, unless otherwise noted.
Table 12.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
G Grade 3
LINE REGULATION 4
E Grade
G Grade
LOAD REGULATION4
E Grade
G Grade
DROPOUT VOLTAGE
SLEEP PIN
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
SUPPLY CURRENT
Sleep Mode
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2
10
5
25
ppm/°C
ppm/°C
4.75 V ≤ VS ≤ 15 V, IOUT = 0 mA
5
10
10
20
ppm/V
ppm/V
VS = 5.80 V, 0 mA ≤ IOUT ≤ 25 mA
5
10
15
20
0.5
1.30
ppm/mA
ppm/mA
V
V
−8
0.8
−8
45
15
V
μA
V
μA
μA
μA
Max
Unit
∆VO/∆VIN
∆VO/∆VLOAD
V S − VO
VS = 5.00 V, ILOAD = 10 mA
VS = 5.80 V, ILOAD = 25 mA
VH
IH
VL
IL
2.4
No load
No load
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
ELECTRICAL CHARACTERISTICS—REF194 @ −40°C ≤ TA ≤ +125°C
@ VS = 5.0 V, −40°C ≤ TA ≤ +125°C, unless otherwise noted.
Table 13.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
G Grade 3
LINE REGULATION 4
E Grade
G Grade
LOAD REGULATION
E Grade
Grade
DROPOUT VOLTAGE
1
2
Symbol
TCVO/°C
Condition
Min
Typ
IOUT = 0 mA
2
10
ppm/°C
ppm/°C
4.75 V ≤ VS ≤ 15 V, IOUT = 0 mA
5
10
ppm/V
ppm/V
VS = 5.80 V, 0 mA ≤ IOUT ≤ 20 mA
5
10
ppm/mA
ppm/mA
V
V
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 5.10 V, ILOAD = 10 mA
VS = 5.95 V, ILOAD = 20 mA
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
Rev. L | Page 10 of 28
0.60
1.45
Data Sheet
REF19x Series
ELECTRICAL CHARACTERISTICS—REF195 @ TA = 25°C
@ VS = 5.10 V, TA = 25°C, unless otherwise noted.
Table 14.
Parameter
INITIAL ACCURACY 1
E Grade
F Grade
G Grade
LINE REGULATION 2
E Grade
F and G Grades
LOAD REGULATION2
E Grade
F and G Grades
DROPOUT VOLTAGE
Symbol
VO
LONG-TERM STABILITY 3
NOISE VOLTAGE
DVO
eN
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
4.998
4.995
4.990
5.0
5.002
5.005
5.010
V
V
V
5.10 V ≤ VS ≤ 15 V, IOUT = 0 mA
2
4
4
8
ppm/V
ppm/V
VS = 6.30 V, 0 mA ≤ IOUT ≤ 30 mA
2
4
4
8
0.50
1.30
ppm/mA
ppm/mA
V
V
mV
μV p-p
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 5.50 V, ILOAD = 10 mA
VS = 6.30 V, ILOAD = 30 mA
1000 hours @ 125°C
0.1 Hz to 10 Hz
1.2
50
1
Initial accuracy does not include shift due to solder heat effect (see the Applications Information section).
Line and load regulation specifications include the effect of self-heating.
3
Long-term stability specification is noncumulative. The drift in subsequent 1000-hour periods is significantly lower than in the first 1000-hour period.
2
ELECTRICAL CHARACTERISTICS—REF195 @ −40°C ≤ TA ≤ +85°C
@ VS = 5.15 V, TA = −40°C ≤ TA ≤ +85°C, unless otherwise noted.
Table 15.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
F Grade
G Grade 3
LINE REGULATION 4
E Grade
F and G Grades
LOAD REGULATION4
E Grade
F and G Grades
DROPOUT VOLTAGE
SLEEP PIN
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
SUPPLY CURRENT
Sleep Mode
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2
5
10
5
10
25
ppm/°C
ppm/°C
ppm/°C
5.15 V ≤ VS ≤ 15 V, IOUT = 0 mA
5
10
10
20
ppm/V
ppm/V
VS = 6.30 V, 0 mA ≤ IOUT ≤ 25 mA
5
10
10
20
0.50
1.30
ppm/mA
ppm/mA
V
V
−8
0.8
−8
45
15
V
μA
V
μA
μA
μA
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 5.50 V, ILOAD = 10 mA
VS = 6.30 V, ILOAD = 25 mA
VH
IH
VL
IL
2.4
No load
No load
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
Rev. L | Page 11 of 28
REF19x Series
Data Sheet
ELECTRICAL CHARACTERISTICS—REF195 @ −40°C ≤ TA ≤ +125°C
@ VS = 5.20 V, −40°C ≤ TA ≤ +125°C, unless otherwise noted.
Table 16.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
F Grade
G Grade 3
LINE REGULATION 4
E Grade
F and G Grades
LOAD REGULATION4
E Grade
F and G Grades
DROPOUT VOLTAGE
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2
5
10
ppm/°C
ppm/°C
ppm/°C
5.20 V ≤ VS ≤ 15 V, IOUT = 0 mA
5
10
ppm/V
ppm/V
VS = 6.45 V, 0 mA ≤ IOUT ≤ 20 mA
5
10
0.60
ppm/mA
ppm/mA
V
1.45
V
ΔVO/ΔVIN
ΔVO/ΔVLOAD
VS − V O
VS = 5.60 V, ILOAD = 10 mA
VS = 6.45 V, ILOAD = 20 mA
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
ELECTRICAL CHARACTERISTICS—REF196 @ TA = 25°C
@ VS = 3.5 V, TA = 25°C, unless otherwise noted.
Table 17.
Parameter
INITIAL ACCURACY 1
G Grade
LINE REGULATION 2
G Grade
LOAD REGULATION2
G Grade
DROPOUT VOLTAGE
Symbol
VO
LONG-TERM STABILITY 3
NOISE VOLTAGE
DVO
eN
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
3.290
3.3
3.310
V
3.50 V ≤ VS ≤ 15 V, IOUT = 0 mA
4
8
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 30 mA
VS = 4.1 V, ILOAD = 10 mA
VS = 4.3 V, ILOAD = 30 mA
1000 hours @ 125°C
0.1 Hz to 10 Hz
6
15
0.80
1.00
ppm/mA
V
V
mV
μV p-p
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
1
1.2
33
Initial accuracy does not include shift due to solder heat effect (see the Applications Information section).
Line and load regulation specifications include the effect of self-heating.
3
Long-term stability specification is noncumulative. The drift in subsequent 1000-hour periods is significantly lower than in the first 1000-hour period.
2
Rev. L | Page 12 of 28
Data Sheet
REF19x Series
ELECTRICAL CHARACTERISTICS—REF196 @ −40°C ≤ TA ≤ +85°C
@ VS = 3.5 V, TA = –40°C ≤ TA ≤ +85°C, unless otherwise noted.
Table 18.
Parameter
TEMPERATURE COEFFICIENT 1, 2
G Grade 3
LINE REGULATION 4
G Grade
LOAD REGULATION4
G Grade
DROPOUT VOLTAGE
SLEEP PIN
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
SUPPLY CURRENT
Sleep Mode
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
10
25
ppm/°C
3.5 V ≤ VS ≤ 15 V, IOUT = 0 mA
10
20
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 25 mA
VS = 4.1 V, ILOAD = 10 mA
VS = 4.3 V, ILOAD = 25 mA
10
20
0.80
1.00
ppm/mA
V
V
−8
0.8
−8
45
15
V
μA
V
μA
μA
μA
Max
Unit
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VH
IH
VL
IL
2.4
No load
No load
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/V0(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
ELECTRICAL CHARACTERISTICS—REF196 @ −40°C ≤ TA ≤ +125°C
@ VS = 3.50 V, −40°C ≤ TA ≤ +125°C, unless otherwise noted.
Table 19.
Parameter
TEMPERATURE COEFFICIENT 1, 2
G Grade 3
LINE REGULATION 4
G Grade
LOAD REGULATION4
G Grade
DROPOUT VOLTAGE
1
2
Symbol
TCVO/°C
Condition
Min
Typ
IOUT = 0 mA
10
ppm/°C
3.50 V ≤ VS ≤ 15 V, IOUT = 0 mA
20
ppm/V
VS = 5.0 V, 0 mA ≤ IOUT ≤ 20 mA
VS = 4.1 V, ILOAD = 10 mA
VS = 4.4 V, ILOAD = 20 mA
20
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
Rev. L | Page 13 of 28
0.80
1.10
ppm/mA
V
V
REF19x Series
Data Sheet
ELECTRICAL CHARACTERISTICS—REF198 @ TA = 25°C
@ VS = 5.0 V, TA = 25°C, unless otherwise noted.
Table 20.
Parameter
INITIAL ACCURACY 1
E Grade
F Grade
G Grade
LINE REGULATION 2
E Grade
F and G Grades
LOAD REGULATION2
E Grade
F and G Grades
DROPOUT VOLTAGE
Symbol
VO
LONG-TERM STABILITY 3
NOISE VOLTAGE
DVO
eN
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
4.094
4.091
4.086
4.096
4.098
4.101
4.106
V
V
V
4.5 V ≤ VS ≤ 15 V, IOUT = 0 mA
2
4
4
8
ppm/V
ppm/V
VS = 5.4 V, 0 mA ≤ IOUT ≤ 30 mA
2
4
4
8
0.502
1.30
ppm/mA
ppm/mA
V
V
mV
μV p-p
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 4.6 V, ILOAD = 10 mA
VS = 5.4 V, ILOAD = 30 mA
1000 hours @ 125°C
0.1 Hz to 10 Hz
1.2
40
1
Initial accuracy does not include shift due to solder heat effect (see the Applications Information section).
Line and load regulation specifications include the effect of self-heating.
3
Long-term stability specification is noncumulative. The drift in subsequent 1000-hour periods is significantly lower than in the first 1000-hour period.
2
ELECTRICAL CHARACTERISTICS—REF198 @ −40°C ≤ TA ≤ +85°C
@ VS = 5.0 V, −40°C ≤ TA ≤ +85°C, unless otherwise noted.
Table 21.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
F Grade
G Grade 3
LINE REGULATION 4
E Grade
F and G Grades
LOAD REGULATION4
E Grade
F and G Grades
DROPOUT VOLTAGE
SLEEP PIN
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
SUPPLY CURRENT
Sleep Mode
1
2
Symbol
TCVO/°C
Condition
Min
Typ
Max
Unit
IOUT = 0 mA
2
5
10
5
10
25
ppm/°C
ppm/°C
ppm/°C
4.5 V ≤ VS ≤ 15 V, IOUT = 0 mA
5
10
10
20
ppm/V
ppm/V
VS = 5.4 V, 0 mA ≤ IOUT ≤ 25 mA
5
10
10
20
0.502
1.30
ppm/mA
ppm/mA
V
V
−8
0.8
−8
45
15
V
μA
V
μA
μA
μA
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 4.6 V, ILOAD = 10 mA
VS = 5.4 V, ILOAD = 25 mA
VH
IH
VL
IL
2.4
No load
No load
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Guaranteed by characterization.
4
Line and load regulation specifications include the effect of self-heating.
Rev. L | Page 14 of 28
Data Sheet
REF19x Series
ELECTRICAL CHARACTERISTICS—REF198 @ −40°C ≤ TA ≤ +125°C
@ VS = 5.0 V, −40°C ≤ TA ≤ +125°C, unless otherwise noted.
Table 22.
Parameter
TEMPERATURE COEFFICIENT 1, 2
E Grade
F Grade
G Grade 3
LINE REGULATION 4
E Grade
F and G Grades
LOAD REGULATION4
E Grade
F and G Grades
DROPOUT VOLTAGE
1
2
Symbol
TCVO/°C
Condition
4
Typ
Max
Unit
IOUT = 0 mA
2
5
10
ppm/°C
ppm/°C
ppm/°C
4.5 V ≤ VS ≤ 15 V, IOUT = 0 mA
5
10
ppm/V
ppm/V
VS = 5.6 V, 0 mA ≤ IOUT ≤ 20 mA
5
10
ppm/mA
ppm/mA
V
V
ΔVO/ΔVIN
ΔVO/ΔVLOAD
V S − VO
VS = 4.7 V, ILOAD = 10 mA
VS = 5.6 V, ILOAD = 20 mA
For proper operation, a 1 μF capacitor is required between the output pin and the GND pin of the device.
TCVO is defined as the ratio of output change with temperature variation to the specified temperature range expressed in ppm/°C.
TCVO = (VMAX − VMIN)/VO(TMAX − TMIN)
3
Min
Guaranteed by characterization.
Line and load regulation specifications include the effect of self-heating.
Rev. L | Page 15 of 28
0.60
1.50
REF19x Series
Data Sheet
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
Table 23.
Parameter
Supply Voltage
Output to GND
Output to GND Short-Circuit Duration
Storage Temperature Range
PDIP, SOIC Package
Operating Temperature Range
REF19x
Junction Temperature Range
PDIP, SOIC Package
Lead Temperature (Soldering 60 sec)
Rating
−0.3 V to +18 V
−0.3 V to VS + 0.3 V
Indefinite
θJA is specified for worst-case conditions; that is, θJA is specified
for the device in socket for PDIP and is specified for the device
soldered in the circuit board for the SOIC and TSSOP packages.
−65°C to +150°C
Package Type
8-Lead PDIP (N)
8-Lead SOIC (R)
8-Lead TSSOP (RU)
−40°C to +125°C
−65°C to +150°C
300°C
Table 24.
ESD CAUTION
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.
Rev. L | Page 16 of 28
θJA
103
158
240
θJC
43
43
43
Unit
°C/W
°C/W
°C/W
Data Sheet
REF19x Series
TYPICAL PERFORMANCE CHARACTERISTICS
50
5.004
3 TYPICAL PARTS
5.15V < VIN < 15V
5.003
BASED ON 600
45 UNITS, 4 RUNS
–40°C ≤ TA ≤ +85°C
40
PERCENTAGE OF PARTS
5.001
5.000
4.999
4.998
4.997
35
30
25
20
15
10
5
–25
0
25
50
TEMPERATURE (°C)
75
0
–20
00371-003
4.996
–50
100
–15
–10
10
15
20
Figure 6. TCVOUT Distribution
Figure 3. REF195 Output Voltage vs. Temperature
32
–5
0
5
TCVOUT (ppm/°C)
00371-006
OUTPUT VOLTAGE (V)
5.002
40
5.15V ≤ VS ≤ 15V
28
35
24
30
SUPPLY CURRENT (μA)
LOAD REGULATION (ppm/V)
NORMAL MODE
–40°C
20
16
+25°C
12
+85°C
8
25
20
15
10
4
5
0
0
–50
10
15
ILOAD (mA)
20
25
30
Figure 4. REF195 Load Regulator vs. ILOAD
20
SLEEP PIN CURRENT (µA)
+25°C
12
–40°C
8
4
–4
–3
–2
VL
–1
6
8
100
–5
+85°C
4
75
–6
10
VIN (V)
12
14
16
0
–50
00371-005
LINE REGULATION (ppm/mA)
0
25
50
TEMPERATURE (°C)
Figure 7. Supply Current vs. Temperature
0mA ≤ IOUT ≤ 25mA
16
0
–25
00371-007
5
Figure 5. REF195 Line Regulator vs. VIN
VH
–25
0
25
50
TEMPERATURE (°C)
75
Figure 8. SLEEP Pin Current vs. Temperature
Rev. L | Page 17 of 28
100
00371-008
0
00371-004
SLEEP MODE
REF19x Series
Data Sheet
5V
0
OFF 100%
RIPPLE REJECTION (dB)
–20
ON
90%
–40
–60
–80
–100
10%
–120
100
1k
10k
FREQUENCY (Hz)
100k
20mV
00371-009
1M
Figure 9. Ripple Rejection vs. Frequency
100µs
Figure 12. Load Transient Response
10μF
10μF
1μF
1kΩ
REF
REF19x
2
6
100%
VG = 2V p-p
1μF
Z
90%
VS = 4V
4
1mA
LOAD
3
2
10%
1
0%
0
30mA
LOAD
2V
10
100
1k
10k
100k
FREQUENCY (Hz)
1M
10M
100µs
00371-011
ZO (Ω)
1μF
2V
200V
4
10mA
0
Figure 13. Load Transient Response Measurement Circuit
Figure 10. Ripple Rejection vs. Frequency Measurement Circuit
VIN = 7V
1μF
Figure 11. Output Impedance vs. Frequency
Figure 14. Power-On Response Time
REF19x
2
VIN = 7V
6
4
1μF
Figure 15. Power-On Response Time Measurement Circuit
Rev. L | Page 18 of 28
00371-014
4
10μF
6
4
OUTPUT
6
00371-010
2
2
00371-013
REF19x
1kΩ
VIN = 15V
REF19x
VIN = 15V
00371-015
10
00371-012
0%
Data Sheet
REF19x Series
5V
5V
ON 100%
90%
90%
IL = 1mA
VOUT
IL = 10mA
10%
10%
200mV
00371-016
2ms
1V
35
REF19x
VOUT
2
6
30
1μF
Figure 17. SLEEP Response Time Measurement Circuit
25
20
15
10
5
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
REF195 DROPOUT VOLTAGE (V)
0.8
Figure 19. Load Current vs. REF195 Dropout Voltage
Rev. L | Page 19 of 28
0.9
00371-019
4
LOAD CURRENT (mA)
3
200µs
Figure 18. Line Transient Response
Figure 16. SLEEP Response Time
VIN = 15V
00371-018
0%
0%
00371-017
OFF
100%
REF19x Series
Data Sheet
APPLICATIONS INFORMATION
OUTPUT SHORT-CIRCUIT BEHAVIOR
SLEEP MODE OPERATION
The REF19x family of devices is totally protected from damage
due to accidental output shorts to GND or to VS. In the event of
an accidental short-circuit condition, the reference device shuts
down and limits its supply current to 40 mA.
All REF19x devices include a sleep capability that is TTL/CMOSlevel compatible. Internally, a pull-up current source to VS is
connected at the SLEEP pin. This permits the SLEEP pin to be
driven from an open collector/drain driver. A logic low or a 0 V
condition on the SLEEP pin is required to turn off the output
stage. During sleep, the output of the references becomes a high
impedance state where its potential would then be determined
by external circuitry. If the sleep feature is not used, it is
recommended that the SLEEP pin be connected to VS (Pin 2).
VS
OUTPUT
BASIC VOLTAGE REFERENCE CONNECTIONS
SLEEP (SHUTDOWN)
Figure 20. Simplified Schematic
REF19x
DEVICE POWER DISSIPATION CONSIDERATIONS
The REF19x family of references is capable of delivering load
currents to 30 mA with an input voltage that ranges from 3.3 V
to 15 V. When these devices are used in applications with large
input voltages, exercise care to avoid exceeding the maximum
internal power dissipation of these devices. Exceeding the
published specifications for maximum power dissipation or
junction temperature can result in premature device failure.
The following formula should be used to calculate the maximum
junction temperature or dissipation of the device:
TJ − TA
θJA
where TJ and TA are the junction and ambient temperatures,
respectively; PD is the device power dissipation; and θJA is the
device package thermal resistance.
OUTPUT VOLTAGE BYPASSING
For stable operation, low dropout voltage regulators and references
generally require a bypass capacitor connected from their VOUT
pins to their GND pins. Although the REF19x family of references is
capable of stable operation with capacitive loads exceeding 100 μF,
a 1 μF capacitor is sufficient to guarantee rated performance.
The addition of a 0.1 μF ceramic capacitor in parallel with the
bypass capacitor improves load current transient performance.
For best line voltage transient performance, it is recommended
that the voltage inputs of these devices be bypassed with a 10 μF
electrolytic capacitor in parallel with a 0.1 μF ceramic capacitor.
0.1µF
8
NC
2
7
SLEEP 3
6
NC
OUTPUT
4
5
NC
+
1µF
TANT
0.1µF
NC = NO CONNECT
Figure 21. Basic Voltage Reference Connections
MEMBRANE SWITCH-CONTROLLED POWER SUPPLY
With output load currents in the tens of mA, the REF19x family of
references can operate as a low dropout power supply in hand-held
instrument applications. In the circuit shown in Figure 22, a
membrane on/off switch is used to control the operation of the
reference. During an initial power-on condition, the SLEEP pin is
held to GND by the 10 kΩ resistor. Recall that this condition (read:
three-state) disables the REF19x output. When the membrane on
switch is pressed, the SLEEP pin is momentarily pulled to VS,
enabling the REF19x output. At this point, current through the 10 kΩ
resistor is reduced and the internal current source connected to the
SLEEP pin takes control. Pin 3 assumes and remains at the same
potential as VS. When the membrane off switch is pressed, the
SLEEP pin is momentarily connected to GND, which once
again disables the REF19x output.
REF19x
VS
1kΩ
5%
ON
NC 1
8
2
7
3
6
4
5
NC
NC
OUTPUT
NC
+1µF
TANT
10kΩ
OFF
NC = NO CONNECT
Figure 22. Membrane Switch Controlled Power Supply
Rev. L | Page 20 of 28
00371-022
PD =
10µF
NC 1
VS
00371-021
00371-020
GND
The circuit in Figure 21 illustrates the basic configuration for
the REF19x family of references. Note the 10 μF/0.1 μF bypass
network on the input and the 1 μF/0.1 μF bypass network on
the output. It is recommended that no connections be made to
Pin 1, Pin 5, Pin 7, and Pin 8. If the sleep feature is not required,
Pin 3 should be connected to VS.
Data Sheet
REF19x Series
SUPPLIER
TP ≥ TC
USER
TP ≤ TC
TC
TC = –5°C
SUPPLIER tP
USER tP
TP
TC = –5°C
tP
MAXIMUM RAMP UP RATE = 3°C/s
TEMPERATURE
MAXIMUM RAMP DOWN RATE = 6°C/s
TL
TSMAX
tL
PREHEAT AREA
TSMIN
tS
00371-123
25
TIME 25°C TO PEAK
TIME
Figure 23. Classification Profile (Not to Scale)
The mechanical stress and heat effect of soldering a part to a
PCB can cause output voltage of a reference to shift in value.
The output voltage of REF195 shifts after the part undergoes the
extreme heat of a lead-free soldering profile, like the one shown
in Figure 23. The materials that make up a semiconductor device
and its package have different rates of expansion and contraction.
The stress on the dice has changed position, causing shift on the
output voltage, after exposed to extreme soldering temperatures.
This shift is similar but more severe than thermal hysteresis.
CURRENT-BOOSTED REFERENCES WITH CURRENT
LIMITING
Whereas the 30 mA rated output current of the REF19x series is
higher than is typical of other reference ICs, it can be boosted to
higher levels, if desired, with the addition of a simple external
PNP transistor, as shown in Figure 25. Full-time current limiting is
used to protect the pass transistor against shorts.
+VS = 6V
TO 9V
(SEE TEXT)
Typical result of soldering temperature effect on REF19x output
value shift is shown in Figure 24. It shows the output shift due
to soldering and does not include mechanical stress.
C2
100µF
25V
R2
1.5kΩ
C3
0.1µF
U1
3
1N4148
(SEE TEXT
ON SLEEP)
5
4
VS
COMMON
REF196
6
VOUT (V)
REF192
REF193
REF196
REF194
REF195
2.5
3.0
3.3
4.5
5.0
F
+VOUT
3.3V
@ 150mA
S
(SEE TABLE)
4
U1
C1
10µF/25V
R3
1.82kΩ (TANTALUM)
S
F
+
R1
VOUT
COMMON
Figure 25. Boosted 3.3 V Referenced with Current Limiting
2
SHIFT DUE TO SOLDER HEAT EFFECT (%)
Figure 24. Output Shift due to Solder Heat Effect
0.16
00371-124
0.14
0.12
0.10
0.08
0.06
0.04
0
0.02
–0.02
–0.04
–0.06
–0.08
–0.10
–0.12
0
–0.14
1
–0.16
NUMBER OF UNITS
Q2
2N3906
+
D1
VC
OUTPUT TABLE
R1
1kΩ
2
6
3
Q1
TIP32A
(SEE TEXT)
R4
2Ω
00371-023
SOLDER HEAT EFFECT
In this circuit, the power supply current of reference U1 flowing
through R1 to R2 develops a base drive for Q1, whose collector
provides the bulk of the output current. With a typical gain of 100
in Q1 for 100 mA to 200 mA loads, U1 is never required to furnish
more than a few mA, so this factor minimizes temperature-related
drift. Short-circuit protection is provided by Q2, which clamps
the drive to Q1 at about 300 mA of load current, with values as
shown in Figure 25. With this separation of control and power
functions, dc stability is optimum, allowing most advantageous
use of premium grade REF19x devices for U1. Of course, load
Rev. L | Page 21 of 28
REF19x Series
Data Sheet
The requirement for a heat sink on Q1 depends on the maximum
input voltage and short-circuit current. With VS = 5 V and a
300 mA current limit, the worst-case dissipation of Q1 is 1.5 W,
less than the TO-220 package 2 W limit. However, if smaller TO-39
or TO-5 package devices, such as the 2N4033, are used, the current
limit should be reduced to keep maximum dissipation below
the package rating. This is accomplished by simply raising R4.
A tantalum output capacitor is used at C1 for its low equivalent
series resistance (ESR), and the higher value is required for stability.
Capacitor C2 provides input bypassing and can be an ordinary
electrolytic.
Shutdown control of the booster stage is an option, and when used,
some cautions are needed. Due to the additional active devices
in the VS line to U1, a direct drive to Pin 3 does not work as with an
unbuffered REF19x device. To enable shutdown control, the
connection from U1 to Q2 is broken at the X, and Diode D1
then allows a CMOS control source, VC, to drive U1 to 3 for on/off
operation. Startup from shutdown is not as clean under heavy
load as it is in basic REF19x series, and can require several
milliseconds under load. Nevertheless, it is still effective and
can fully control 150 mA loads. When shutdown control is
used, heavy capacitive loads should be minimized.
NEGATIVE PRECISION REFERENCE WITHOUT
PRECISION RESISTORS
In many current-output CMOS DAC applications where the output
signal voltage must be the same polarity as the reference voltage, it
is often necessary to reconfigure a current-switching DAC into
a voltage-switching DAC using a 1.25 V reference, an op amp,
and a pair of resistors. Using a current-switching DAC directly
requires an additional operational amplifier at the output to
reinvert the signal. A negative voltage reference is then desirable
because an additional operational amplifier is not required for
either reinversion (current-switching mode) or amplification
(voltage-switching mode) of the DAC output voltage. In general,
any positive voltage reference can be converted into a negative
voltage reference using an operational amplifier and a pair of
matched resistors in an inverting configuration. The disadvantage
to this approach is that the largest single source of error in the
circuit is the relative matching of the resistors used.
The circuit illustrated in Figure 26 avoids the need for tightly
matched resistors by using an active integrator circuit. In this
circuit, the output of the voltage reference provides the input
drive for the integrator. To maintain circuit equilibrium, the
VS
10kΩ
2N3906
SLEEP
TTL/CMOS
2
VS
3
SLEEP OUTPUT 6
1µF
1kΩ
+5V
REF19x
GND
10kΩ
100Ω
A1
1µF
4
–VREF
100kΩ
–5V
A1 = 1/2 OP295,
1/2 OP291
00371-024
Because of the current limiting configuration, the dropout voltage
circuit is raised about 1.1 V over that of the REF19x devices, due to
the VBE of Q1 and the drop across Current Sense Resistor R4.
However, overall dropout is typically still low enough to allow
operation of a 5 V to 3.3 V regulator/reference using the REF196 for
U1 as noted, with a VS as low as 4.5 V and a load current of 150 mA.
integrator adjusts its output to establish the proper relationship
between the VOUT and GND references. Thus, any desired negative
output voltage can be selected by substituting for the appropriate
reference IC. The sleep feature is maintained in the circuit with
the simple addition of a PNP transistor and a 10 kΩ resistor.
Figure 26. Negative Precision Voltage Reference Uses No Precision Resistors
One caveat to this approach is that although rail-to-rail output
amplifiers work best in the application, these operational amplifiers
require a finite amount (mV) of headroom when required to provide
any load current; consider this issue when choosing the negative
supply for the circuit.
STACKING REFERENCE ICs FOR ARBITRARY
OUTPUTS
Some applications may require two reference voltage sources that
are a combined sum of standard outputs. The circuit in Figure 27
shows how this stacked output reference can be implemented.
Two reference ICs are used, fed from a common unregulated input,
VS. The outputs of the individual ICs are connected in series, as
shown in Figure 27, which provide two output voltages, VOUT1 and
VOUT2. VOUT1 is the terminal voltage of U1, whereas VOUT2 is the
sum of this voltage and the terminal voltage of U2. U1 and U2
are chosen for the two voltages that supply the required outputs
(see Table 1). If, for example, both U1 and U2 are REF192s, the
two outputs are 2.5 V and 5.0 V.
OUTPUT TABLE
U1/U2
+VS
VS > VOUT2 + 0.15V
VOUT1 (V) VOUT2 (V)
REF192/REF192 2.5
REF192/REF194 2.5
REF192/REF195 2.5
5.0
7.0
7.5
2
C1
0.1µF
U2
3
REF19x
+VOUT2
6
(SEE TABLE)
VO (U2)
4
+
C2
1µF
2
C3
0.1µF
U1
3
REF19x
4
VIN
COMMON
Rev. L | Page 22 of 28
6
(SEE TABLE)
VO (U1)
+ C4
1µF
R1
3.9kΩ
+VOUT1
(SEE TEXT)
VOUT
COMMON
Figure 27. Stacking Voltage References with the REF19x
00371-025
management should still be exercised. A short, heavy, low dc
resistance (DCR) conductor should be used from U1 to 6 to the VOUT
Sense Point S, where the collector of Q1 connects to the load, Point F.
Data Sheet
REF19x Series
+VS
VS > VOUT2 + 0.15V
2
U1
REF192
4
VIN
COMMON
D1
AD589
6
VO (U1)
VO (D1)
+
C2
1μF
+ C3
1μF
R1
4.99kΩ
+VOUT2
3.735V
(SEE TEXT)
+VOUT1
1.235V
VOUT
COMMON
Figure 28. Stacking Voltage References with the REF192
PRECISION CURRENT SOURCE
2
VS
REF19x
3
SLEEP
OUTPUT 6
GND
4
1µF
R1
ISY
ADJUST
P1
IOUT
VIN ≥ IOUT × RL (MAX) + VSY (MIN)
IOUT =
VOUT
RSET
VOUT
RSET
RSET
RL
+ ISY (REF19x)
FOR EXAMPLE, REF195: VOUT = 5V
IOUT = 5mA
R1 = 953Ω
P1 = 100Ω, 10-TURN
>> ISY
Figure 29. A Low Dropout, Precision Current Source
SWITCHED OUTPUT 5 V/3.3 V REFERENCE
Applications often require digital control of reference voltages,
selecting between one stable voltage and a second. With the
sleep feature inherent to the REF19x series, switched output
reference configurations are easily implemented with little
additional hardware.
The circuit in Figure 30 shows the general technique, which takes
advantage of the output wire-OR capability of the REF19x device
family. When off, a REF19x device is effectively an open circuit
at the output node with respect to the power supply. When on, a
REF19x device can source current up to its current rating, but
sink only a few μA (essentially, just the relatively low current of the
internal output scaling divider). Consequently, when two devices
are wired together at their common outputs, the output voltage
is the same as the output voltage for the on device. The off state
device draws a small standby current of 15 μA (maximum), but
otherwise does not interfere with operation of the on device, which
can operate to its full current rating. Note that the two devices in
the circuit conveniently share both input and output capacitors,
and with CMOS logic drive, it is power efficient.
OUTPUT TABLE
In low power applications, the need often arises for a precision
current source that can operate on low supply voltages. As
shown in Figure 29, any one of the devices in the REF19x family
of references can be configured as a precision current source.
The circuit configuration illustrated is a floating current source
with a grounded load. The output voltage of the reference is
bootstrapped across RSET, which sets the output current into the
load. With this configuration, circuit precision is maintained for
load currents in the range from the reference’s supply current
(typically 30 μA) to approximately 30 mA. The low dropout
voltage of these devices maximizes the current source’s output
voltage compliance without excess headroom.
U1/U2
VC*
VOUT (V)
REF195/ HIGH 5.0
REF196 LOW 3.3
REF194/ HIGH 4.5
REF195 LOW 5.0
+VS = 6V
2
VC
1
2
3
4
*CMOS LOGIC LEVELS
U1
3
REF19x
6
(SEE TABLE)
U3A
U3B
74HC04 74HC04
4
+VOUT
2
U2
3
REF19x
6
+ C2
1µF
(SEE TABLE)
C1
0.1µF
4
VIN
COMMON
VOUT
COMMON
Figure 30. Switched Output Reference
Rev. L | Page 23 of 28
00371-028
3
00371-026
C1
0.1μF
VS
00371-027
Although this concept is simple, some cautions are needed. Because
the lower reference circuit must sink a small bias current from U2
(50 μA to 100 μA), plus the base current from the series PNP output
transistor in U2, either the external load of U1 or R1 must provide
a path for this current. If the U1 minimum load is not well defined,
Resistor R1 should be used, set to a value that conservatively passes
600 μA of current with the applicable VOUT1 across it. Note that the
two U1 and U2 reference circuits are locally treated as macrocells,
each having its own bypasses at input and output for best stability.
Both U1 and U2 in this circuit can source dc currents up to
their full rating. The minimum input voltage, VS, is determined by
the sum of the outputs, VOUT2, plus the dropout voltage of U2.
A related variation on stacking two 3-terminal references is shown
in Figure 28, where U1, a REF192, is stacked with a 2-terminal
reference diode, such as the AD589. Like the 3-terminal stacked
reference shown in Figure 27, this circuit provides two outputs,
VOUT1 and VOUT2, which are the individual terminal voltages of D1
and U1, respectively. Here this is 1.235 V and 2.5 V, which provides a
VOUT2 of 3.735 V. When using 2-terminal reference diodes, such as
D1, the rated minimum and maximum device currents must be
observed, and the maximum load current from VOUT1 can be no
greater than the current setup by R1 and VO (U1). When VO
(U1) is equal to 2.5 V, R1 provides a 500 μA bias to D1, so the
maximum load current available at VOUT1 is 450 μA or less.
REF19x Series
Data Sheet
Due to the nature of the wire-OR, one application caveat should
be understood about this circuit. Because U1 and U2 can only
source current effectively, negative going output voltage changes,
which require the sinking of current, necessarily take longer than
positive going changes. In practice, this means that the circuit is
quite fast when undergoing a transition from 3.3 V to 5 V, but the
transition from 5 V to 3.3 V takes longer. Exactly how much
longer is a function of the load resistance, RL, seen at the output and
the typical 1 μF value of C2. In general, a conservative transition
time is approximately several milliseconds for load resistances
in the range of 100 Ω to 1 kΩ. Note that for highest accuracy at
the new output voltage, several time constants should be allowed
(for example, >7.6 time constants for
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