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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
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 resistors, low noise and good long term stability result.
Careful design of the LM185-1.2 has made the device exceptionally 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 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
■
LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode
January 30, 2008
Connection Diagrams
T0-92
Plastic Package (Z)
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
SO Package
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
551810
551809
SOT23
* 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
Metal Can Package (H)
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
551833
TO-46
551806
© 2008 National Semiconductor Corporation 5518 www.national.com
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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 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
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.
LM385-1.2 0°C to 70°C
Electrical Characteristics (Note 4)
LM185-1.2/LM285-1.2/LM385-1.2
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, 1.2351.223 1.223 1.205 V(Min)
Voltage
10μA ≤ IR ≤ 20mA
Minimum Operating 8 10 20 15 20 15 20
Current
Reverse Breakdown
LM385M3-1.2 10 15
10μA ≤ IR ≤ 1mA
1.247 1.247 1.260 V(Max)
μA
(Max)
1 1.5 1 1.5 1 1.5 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
(rms)
Long Term Stability
IR = 100μA,
10Hz ≤ f ≤ 10kHz
IR = 100μA, T = 1000 Hr,
60
20
μV
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
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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)
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
T
and T
MAX
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.
, divided by T
MIN
MAX
− T
. The measured temperatures are −55°C, −40°C, 0°C, 25°C, 70°C, 85°C, 125°C.
MIN
N/A 80°C/W N/A N/A
Typical Performance Characteristics
LM185-1.2/LM285-1.2/LM385-1.2
Reverse Characteristics
Forward Characteristics
551813
Reverse Characteristics
551814
Temperature Drift of 3
Representative Units
551815
551816
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Reverse Dynamic Impedance
LM185-1.2/LM285-1.2/LM385-1.2
551817
Reverse Dynamic Impedance
551818
Noise Voltage
Response Time
551819
Filtered Output Noise
551820
551821
Typical Applications
Wide Input
Range Reference
551808
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Micropower Reference
from 9V Battery
551822
Reference from
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1.5V Battery
551823
Micropower* 5V Regulator
LM185-1.2/LM285-1.2/LM385-1.2
*IQ ≃20μA standby current
Precision 1μA to 1mA Current Sources
551826
*IQ ≃ 30μA
Micropower* 10V Reference
551825
551824
551827
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METER THERMOMETERS
0°C−100°C Thermometer
†IQ at 1.3V″500μA
IQ at 1.6V″2.4mA
Lower Power Thermometer
LM185-1.2/LM285-1.2/LM385-1.2
Calibration
1. Short LM385-1.2, adjust R3 for I
2. Remove short, adjust R2 for correct reading in centigrade
= temp at 1μA/°K
OUT
0°F−50°F Thermometer
Calibration
1. Short LM385-1.2, adjust R3 for I
2. Remove short, adjust R2 for correct reading in °F
= temp at 1.8μA/°K
OUT
Micropower Thermocouple Cold Junction Compensator
551828
551830
*2N3638 or 2N2907 select for inverse HFE ″ 5
†Select for operation at 1.3V
‡IQ ≃ 600μA to 900μA
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.
551829
ThermocoupleSeebeck R1 R2 Voltage Voltage
Type Coefficient
(Ω) (Ω)
AcrossR1Across
R2
(μV/°C)
@ 25°C (mV)
(mV)
J 52.3 5231.24k15.60 14.32
T 42.8 4321k 12.77 11.78
K 40.8 41
2
S 6.4 63.
4
12.17 11.17
95
3Ω
1.908 1.766
15
0Ω
Typical supply current 50μA
551831
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Centigrade Thermometer
LM185-1.2/LM285-1.2/LM385-1.2
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 voltage = 50μA to 150μA
Schematic Diagram
551801
551807
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Physical Dimensions inches (millimeters) unless otherwise noted
LM185-1.2/LM285-1.2/LM385-1.2
Order Number LM185H-1.2, LM185H-1.2/883, LM185BXH-1.2, LM185BYH-1.2, LM285H-1.2, or LM285BXH-1.2
TO-46 Metal Can Package (H)
NS Package Number H02A
SOT-23 Package (M3)
Order Number LM385M3-1.2
NS Package Number MF03A
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LM185-1.2/LM285-1.2/LM385-1.2
Order Number LM285M-1.2, LM285BXM-1.2, LM285BYM-1.2
LM385M-1.2, LM385BM-1.2, LM385BXM-1.2, LM385BYM-1.2
Small Outline (SO-8) Package
NS Package Number M08A
Order Number LM285Z-1.2, LM285BXZ-1.2
LM285BYZ-1.2, LM385Z-1.2, LM385BZ-1.2
TO-92 Plastic Package (Z)
LM385BXZ-1.2 or LM385BYZ-1.2
NS Package Number Z03A
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Notes
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LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR
SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL
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