LM185-1.2,LM285-1.2,LM385-1.2
LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode
Literature Number: SNVS742D
January 30, 2008
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-ter-
minal band-gap voltage regulator diodes. Operating over a
10μA to 20mA current range, they feature exceptionally 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 transistors and re-
sistors, low noise and good long term stability result.
Careful design of the LM185-1.2 has made the device excep-
tionally tolerant of capacitive loading, making it easy to use in
almost any reference application. The wide dynamic operat-
ing 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 carrier package.
Features
■±1% and 2% initial tolerance
■Operating current of 10μA to 20mA
■1Ω dynamic impedance
■Low temperature coefficient
■Low voltage reference—1.235V
■2.5V device and adjustable device also available
■LM185-2.5 series and LM185 series, respectively
Connection Diagrams
T0-92
Plastic Package (Z)
551810
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
551833
* 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 MF03A
SO Package
551809
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)
551806
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
© 2008 National Semiconductor Corporation 5518 www.national.com
LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode
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 30mA
Forward Current 10mA
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
ESD Susceptibility (Note 9) 2kV
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, 1.23
5
1.223 1.223 1.205 V(Min)
Voltage 10μA ≤ IR ≤ 20mA 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 10μA ≤ IR ≤ 1mA 1 1.5 11.5 11.5 mV
Voltage Change (Max)
with Current 1mA ≤ IR ≤ 20mA 10 20 20 25 20 25 mV
(Max)
Reverse Dynamic IR = 100μA, f = 20Hz 1 Ω
Impedance
Wideband Noise IR = 100μA, 60 μV
(rms) 10Hz ≤ f ≤ 10kHz
Long Term Stability IR = 100μA, T = 1000 Hr, 20 ppm
TA = 25°C ±0.1°C
Average Temperature IR = 100μA
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 intended 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, Tj max is:
LM185 150°C
LM285 125°C
LM385 100°C
www.national.com 2
LM185-1.2/LM285-1.2/LM385-1.2
Thermal Resistance TO-92 TO-46 SO-8 SOT23
θJA (junction to ambient) 180°C/W (0.4″ leads) 440°C/W 165°C/W 283°C/W
170°C/W (0.125″ leads)
θJC (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.
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 − TMIN. 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.
Note 9: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.
Typical Performance Characteristics
Reverse Characteristics
551813
Reverse Characteristics
551814
Forward Characteristics
551815
Temperature Drift of 3
Representative Units
551816
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LM185-1.2/LM285-1.2/LM385-1.2
Reverse Dynamic Impedance
551817
Reverse Dynamic Impedance
551818
Noise Voltage
551819
Filtered Output Noise
551820
Response Time
551821
Typical Applications
Wide Input
Range Reference
551808
Micropower Reference
from 9V Battery
551822
Reference from
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LM185-1.2/LM285-1.2/LM385-1.2
1.5V Battery
551823
Micropower* 5V Regulator
551824
*IQ ≃ 30μA
Micropower* 10V Reference
551825
*IQ ≃20μA standby current
Precision 1μA to 1mA Current Sources
551826
551827
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LM185-1.2/LM285-1.2/LM385-1.2
METER THERMOMETERS
0°C−100°C Thermometer
551828
Calibration
1. Short LM385-1.2, adjust R3 for IOUT= temp at 1μA/°K
2. Remove short, adjust R2 for correct reading in centigrade
†IQ at 1.3V″500μA
IQ at 1.6V″2.4mA
Lower Power Thermometer
551829
*2N3638 or 2N2907 select for inverse HFE ″ 5
†Select for operation at 1.3V
‡IQ ≃ 600μA to 900μA
0°F−50°F Thermometer
551830
Calibration
1. Short LM385-1.2, adjust R3 for IOUT= temp at 1.8μA/°K
2. Remove short, adjust R2 for correct reading in °F
Micropower Thermocouple Cold Junction Compensator
551831
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.
Thermocoup
le
Seebeck R1 R2 Voltage Voltage
Type Coefficient (Ω) (Ω) Across
R1
Across
R2
(μV/°C) @ 25°C (mV)
(mV)
J 52.3 52
3
1.2
4k
15.60 14.32
T 42.8 43
2
1k 12.77 11.78
K 40.8 41
2
95
3Ω
12.17 11.17
S 6.4 63.
4
15
0Ω
1.908 1.766
Typical supply current 50μA
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LM185-1.2/LM285-1.2/LM385-1.2
Centigrade Thermometer
551801
Calibration
1. Adjust R1 so that V1 = temp at 1mV/°K
2. Adjust V2 to 273.2mV
†IQ for 1.3V to 1.6V battery volt-
age = 50μA to 150μA
Schematic Diagram
551807
7 www.national.com
LM185-1.2/LM285-1.2/LM385-1.2
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 MF03A
www.national.com 8
LM185-1.2/LM285-1.2/LM385-1.2
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
9 www.national.com
LM185-1.2/LM285-1.2/LM385-1.2
Notes
LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode
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