LM185-1.2/LM285-1.2/LM385-1.2
Micropower Voltage Reference Diode
General Description
The LM185-1.2/LM285-1.2/LM385-1.2 are micropower
2-terminal band-gap voltage regulator diodes. Operating
over a 10 µAto 20 mAcurrent range, they feature exception-
ally low dynamic impedance and good temperature stability.
On-chip trimming is used to provide tight voltage tolerance.
Since the LM185-1.2 band-gap reference uses only transis-
tors and resistors, low noise and good long term stability re-
sult.
Careful design of the LM185-1.2 has made the device ex-
ceptionally tolerant of capacitive loading, making it easy to
use in almost any reference application. The wide dynamic
operating range allows its use with widely varying supplies
with excellent regulation.
The extremely low power drain of the LM185-1.2 makes it
useful for micropower circuitry. This voltage reference can be
used to make portable meters, regulators or general purpose
analog circuitry with battery life approaching shelf life.
Further, the wide operating current allows it to replace older
references with a tighter tolerance part.
The LM185-1.2 is rated for operation over a −55˚C to 125˚C
temperature range while the LM285-1.2 is rated −40˚C to
85˚C and the LM385-1.2 0˚C to 70˚C. The LM185-1.2/
LM285-1.2 are available in a hermetic TO-46 package and
the LM285-1.2/LM385-1.2 are also available in a low-cost
TO-92 molded package, as well as SO and SOT-23. The
LM185-1.2 is also available in a hermetic leadless chip car-
rier package.
Features
n±4mV(
±
0.3%) max. initial tolerance (A grade)
nOperating current of 10 µA to 20 mA
n0.6Ωmax dynamic impedance (A grade)
nLow temperature coefficient
nLow voltage reference—1.235V
n2.5V device and adjustable device also available
nLM185-2.5 series and LM185 series, respectively
Connection Diagrams
T0-92
Plastic Package (Z)
DS005518-10
Bottom View
Order Number LM285Z-1.2,
LM285BXZ-1.2, LM285BYZ-1.2
LM385Z-1.2, LM385BZ-1.2
LM385BXZ-1.2 or LM385BYZ-1.2
See NS Package Number Z03A
SOT23
DS005518-33
*Pin 3 is attached to the Die Attach Pad (DAP) and should be connected
to Pin 2 or left floating.
Order Number LM385M3-1.2
See NS Package Number MA03B
January 2000
LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode
© 2000 National Semiconductor Corporation DS005518 www.national.com
Connection Diagrams (Continued)
SO Package
DS005518-9
Order Number LM285M-1.2,
LM285BXM-1.2, LM285BYM-1.2
LM385M-1.2, LM385BM-1.2
LM385BXM-1.2 or LM385BYM-1.2
See NS Package Number M08A
TO-46
Metal Can Package (H)
DS005518-6
Bottom View
Order Number LM185H-1.2, LM185H-1.2/883,
LM185BXH-1.2, LM185BYH-1.2
LM285H-1.2 or LM285BXH-1.2
See NS Package Number H02A
LM185-1.2/LM285-1.2/LM385-1.2
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
(Note 2)
Reverse Current 30 mA
Forward Current 10 mA
Operating Temperature Range (Note 3)
LM185-1.2 −55˚C to +125˚C
LM285-1.2 −40˚C to +85˚C
LM385-1.2 0˚C to 70˚C
Storage Temperature −55˚C to +150˚C
Soldering Information
TO-92 package: 10 sec. 260˚C
TO-46 package:10 sec. 300˚C
SO and SOT Pkg.
Vapor phase (60 sec.) 215˚C
Infrared (15 sec.) 220˚C
See AN-450 “Surface Mounting Methods and Their Effect
on Product Reliability” for other methods of soldering
surface mount devices.
Electrical Characteristics (Note 4)
LM185-1.2
LM185BX-1.2 LM385B-1.2
LM185BY-1.2 LM385BX-1.2 LM385-1.2
LM285-1.2 LM385BY-1.2 Units
Parameter Conditions Typ LM285BX-1.2 (Limit)
LM285BY-1.2
Tested Design Tested Design Tested Design
Limit Limit Limit Limit Limit Limit
(Notes
5, 8) (Note 6) (Note 5) (Note 6) (Note 5) (Note 6)
Reverse Breakdown TA=25˚C, 1.235 1.223 1.223 1.205 V(Min)
Voltage 10 µA ≤IR≤20 mA 1.247 1.247 1.260 V(Max)
Minimum Operating 8 10 20 15 20 15 20 µA
Current LM385M3-1.2 10 15 (Max)
Reverse Breakdown 10 µA ≤IR≤1mA 1 1.5 11.5 11.5 mV
Voltage Change (Max)
with Current 1 mA ≤IR≤20 mA 10 20 20 25 20 25 mV
(Max)
Reverse Dynamic IR=100 µA, f =20 Hz 1 Ω
Impedance
Wideband Noise IR=100 µA, 60 µV
(rms) 10 Hz ≤f≤10 kHz
Long Term Stability IR=100 µA, T =1000 Hr, 20 ppm
TA=25˚C ±0.1˚C
Average Temperature IR=100 µA
Coefficient (Note 7) X Suffix 30 30 ppm/˚C
Y Suffix 50 50 ppm/˚C
All Others 150 150 150 ppm/˚C
(Max)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in-
tended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The
guaranteed specifications apply only for the test conditions listed.
Note 2: Refer to RETS185H-1.2 for military specifications.
Note 3: For elevated temperature operation, Tjmax is:
LM185 150˚C
LM285 125˚C
LM385 100˚C
Thermal Resistance TO-92 TO-46 SO-8 SOT23
θ
JA
(junction to ambient) 180˚C/W (0.4" leads) 440˚C/W 165˚C/W 283˚C/W
170˚C/W (0.125" leads)
θ
JC
(junction to case) N/A 80˚C/W N/A N/A
Note 4: Parameters identified with boldface type apply at temperature extremes. All other numbers apply at TA=TJ=25˚C.
LM185-1.2/LM285-1.2/LM385-1.2
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Electrical Characteristics (Note 4) (Continued)
Note 5: Guaranteed and 100%production tested.
Note 6: Guaranteed, but not 100%production tested. These limits are not used to calculate average outgoing quality levels.
Note 7: The average temperature coefficient is defined as the maximum deviation of reference voltage at all measured temperatures between the operating TMAX
and TMIN, divided by TMAX −T
MIN. The measured temperatures are −55˚C, −40˚C, 0˚C, 25˚C, 70˚C, 85˚C, 125˚C.
Note 8: A military RETS electrical specification is available on request.
Typical Performance Characteristics
Reverse Characteristics
DS005518-13
Reverse Characteristics
DS005518-14
Forward Characteristics
DS005518-15
Temperature Drift of 3
Representative Units
DS005518-16
Reverse Dynamic Impedance
DS005518-17
Reverse Dynamic Impedance
DS005518-18
Noise Voltage
DS005518-19
Filtered Output Noise
DS005518-20
Response Time
DS005518-21
LM185-1.2/LM285-1.2/LM385-1.2
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Typical Applications
Wide Input
Range Reference
DS005518-8
Micropower Reference
from 9V Battery
DS005518-22
Reference from
1.5V Battery
DS005518-23
Micropower*5V Regulator
DS005518-24
*IQ≅30 µA
Micropower*10V Reference
DS005518-25
*IQ≅20 µA standby current
Precision 1 µA to 1 mA Current Sources
DS005518-26
DS005518-27
LM185-1.2/LM285-1.2/LM385-1.2
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Typical Applications (Continued)
METER THERMOMETERS
0˚C−100˚C Thermometer
DS005518-28
Calibration
1. Short LM385-1.2, adjust R3 for IOUT=temp at 1 µA/˚K
2. Remove short, adjust R2 for correct reading in centigrade
†IQat 1.3V≅500 µA
IQat 1.6V≅2.4 mA
Lower Power Thermometer
DS005518-29
*2N3638 or 2N2907 select for inverse HFE ≅5
†Select for operation at 1.3V
‡IQ≅600 µA to 900 µA
0˚F−50˚F Thermometer
DS005518-30
Calibration
1. Short LM385-1.2, adjust R3 for IOUT=temp at 1.8 µA/˚K
2. Remove short, adjust R2 for correct reading in ˚F
Micropower Thermocouple Cold Junction
Compensator
DS005518-31
Adjustment Procedure
1. Adjust TC ADJ pot until voltage across R1 equals Kelvin temperature
multiplied by the thermocouple Seebeck coefficient.
2. Adjust zero ADJ pot until voltage across R2 equals the thermocouple
Seebeck coefficient multiplied by 273.2.
Thermocouple Seebeck R1 R2 Voltage Voltage
Type Coefficient (Ω)(Ω) Across R1 Across R2
(µV/˚C) @25˚C (mV)
(mV)
J 52.3 523 1.24k 15.60 14.32
T 42.8 432 1k 12.77 11.78
K 40.8 412 953Ω12.17 11.17
S 6.4 63.4 150Ω1.908 1.766
Typical supply current 50 µA
LM185-1.2/LM285-1.2/LM385-1.2
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Typical Applications (Continued)
Schematic Diagram
Centigrade Thermometer
DS005518-1
Calibration
1. Adjust R1 so that V1 =temp at 1 mV/˚K
2. Adjust V2 to 273.2 mV
†IQfor 1.3V to 1.6V battery volt-
age =50 µA to 150 µA
DS005518-7
LM185-1.2/LM285-1.2/LM385-1.2
www.national.com7
Physical Dimensions inches (millimeters) unless otherwise noted
TO-46 Metal Can Package (H)
Order Number LM185H-1.2, LM185H-1.2/883, LM185BXH-1.2, LM185BYH-1.2, LM285H-1.2, or LM285BXH-1.2
NS Package Number H02A
SOT-23 Package (M3)
Order Number LM385M3-1.2
NS Package Number MA03B
LM185-1.2/LM285-1.2/LM385-1.2
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
Small Outline (SO-8) Package
Order Number LM285M-1.2, LM285BXM-1.2, LM285BYM-1.2
LM385M-1.2, LM385BM-1.2, LM385BXM-1.2, LM385BYM-1.2
NS Package Number M08A
TO-92 Plastic Package (Z)
Order Number LM285Z-1.2, LM285BXZ-1.2
LM285BYZ-1.2, LM385Z-1.2, LM385BZ-1.2
LM385BXZ-1.2 or LM385BYZ-1.2
NS Package Number Z03A
LM185-1.2/LM285-1.2/LM385-1.2
www.national.com9
Notes
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
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www.national.com
LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
