LM185-2.5,LM285-2.5,LM385-2.5
LM185-2.5/LM285-2.5/LM385-2.5 Micropower Voltage Reference Diode
Literature Number: SNVS743C
January 30, 2008
LM185-2.5/LM285-2.5/LM385-2.5
Micropower Voltage Reference Diode
General Description
The LM185-2.5/LM285-2.5/LM385-2.5 are micropower 2-ter-
minal band-gap voltage regulator diodes. Operating over a 20
μA to 20 mA current range, they feature exceptionally low dy-
namic impedance and good temperature stability. On-chip
trimming is used to provide tight voltage tolerance. Since the
LM-185-2.5 band-gap reference uses only transistors and re-
sistors, low noise and good long term stability result.
Careful design of the LM185-2.5 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 LM185-2.5 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. Fur-
ther, the wide operating current allows it to replace older
references with a tighter tolerance part. For applications re-
quiring 1.2V see LM185-1.2.
The LM185-2.5 is rated for operation over a −55°C to 125°C
temperature range while the LM285-2.5 is rated −40°C to 85°
C and the LM385-2.5 0°C to 70°C. The LM185-2.5/LM285-2.5
are available in a hermetic TO-46 package and the
LM285-2.5/LM385-2.5 are also available in a low-cost TO-92
molded package, as well as S.O. and SOT-23. The
LM185-2.5 is also available in a hermetic leadless chip carrier
package.
Features
■±20 mV (±0.8%) max. initial tolerance (A grade)
■Operating current of 20 μA to 20 mA
■0.6Ω dynamic impedance (A grade)
■Low temperature coefficient
■Low voltage reference—2.5V
■1.2V device and adjustable device also available—
LM185-1.2 series and LM185 series, respectively
Connection Diagrams
TO-92
Plastic Package
551908
Bottom View
Order Number LM285Z-2.5,
LM285BXZ-2.5, LM285BYZ-2.5
LM385Z-2.5, LM385AXZ-2.5
LM385AYZ-2.5, LM385BZ-2.5,
LM385BXZ-2.5 or LM385BYZ-2.5
See NS Package Number Z03A
SO Package
551911
Order Number LM285M-2.5,
LM285BXM-2.5, LM285BYM-2.5
LM385M-2.5, LM385BM-2.5
LM385BXM-2.5 or LM385BYM-2.5
See NS Package Number M08A
SOT-23
551929
* Pin 3 is attached to the Die Attach Pad (DAP) and should be connected to Pin 2 or left floating.
Order Number LM385M3-2.5
See NS Package Number MA03B
© 2008 National Semiconductor Corporation 5519 www.national.com
LM185-2.5/LM285-2.5/LM385-2.5 Micropower Voltage Reference Diode
LCC
Leadless Chip Carrier
551914
Order Number LM185E-2.5/883
See NS Package Number E20A
TO-46
Metal Can Package
551913
Bottom View
Order Number LM185H-2.5,
LM185H-2.5/883, LM185BXH-2.5,
LM185BXH-2.5/883, LM185BYH-2.5,
LM185BYH2.5/883, LM285H-2.5,
or LM285BYH-2.5
See NS Package Number H02A
www.national.com 2
LM185-2.5/LM285-2.5/LM385-2.5
Absolute Maximum Ratings (Notes 1, 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Reverse Current 30 mA
Forward Current 10 mA
Operating Temperature
Range (Note 3)
LM185-2.5 −55°C to + 125°C
LM285-2.5 −40°C to + 85°C
LM385-2.5 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 Package
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)
Parameter Conditions Typ
LM385A-2.5
Units
(Limits)
LM385AX-2.5
LM385AY-2.5
Tested Design
Limit Limit
(Note 5) (Note 6)
Reverse Breakdown IR = 100 μA2.500 2.480 V(Min)
Voltage 2.520 V(Max)
2.500 2.470 V(Min)
2.530 V(Max)
Minimum Operating 12 18 20 μA
Current (Max)
Reverse Breakdown IMIN ≤ IR ≤ 1mA 1 1.5 mV
Voltage Change with (Max)
Current 1 mA ≤ IR ≤ 20 mA 10 20 mV
(Max)
Reverse Dynamic IR = 100 μA, 0.2 0.6 Ω
Impedance f = 20 Hz 1.5
Wideband Noise (rms) IR = 100 μA120 μV
10 Hz ≤ f ≤ 10 kHz
Long Term Stability IR = 100 μA,
T = 1000 Hr, 20 ppm
TA = 25°C ±0.1°C
Average Temperature IMIN ≤ IR ≤ 20 mA
Coefficient (Note 7) X Suffix 30 ppm/°C
Y Suffix 50 (Max)
All Others 150
3 www.national.com
LM185-2.5/LM285-2.5/LM385-2.5
Electrical Characteristics
LM185-2.5
LM185BX-2.5 LM385B-2.5
LM185BY-2.5 LM385BX-2.5 LM385-2.5 Units
LM285-2.5 LM385BY-2.5 (Limit)
Parameter Conditions Typ LM285BX-2.5
LM285BY-2.5
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, 2.5 2.462 2.462 2.425 V(Min)
Voltage 20 μA ≤ IR ≤ 20 mA 2.538 2.538 2.575 V(Max)
Minimum Operating
Current
13 20 30 20 30 20 30 μA
(Max)
LM385M3-2.5 15 20
Reverse
Breakdown Voltage
Change with
Current
20 μA ≤ IR ≤ 1 mA 1 1.5 2.0 2.5 2.0 2.5 mV
(Max)
1 mA ≤ IR ≤ 20 mA 10 20 20 25 20 25 mV
(Max)
Reverse Dynamic IR = 100 μA, 1 Ω
Impedance f = 20 Hz
Wideband Noise
(rms)
IR = 100 μA, 120 μV
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
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-2.5 for military specifications.
Note 3: For elevated temperature operation, TJ MAX is:
LM185 150°C
LM285 125°C
LM385 100°C
Thermal Resistance TO-92 TO-46 SO-8 SOT-23
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 available on request.
Note 9: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.
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LM185-2.5/LM285-2.5/LM385-2.5
Typical Performance Characteristics
Reverse Characteristics
551915
Reverse Characteristics
551916
Forward Characteristics
551917
Temperature Drift
551918
Reverse Dynamic
Impedance
551919
Reverse Dynamic
Impedance
551920
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LM185-2.5/LM285-2.5/LM385-2.5
Noise Voltage
551921
Filtered Output Noise
551922
Response Time
551923
Applications
Wide Input Range Reference
551912
Micropower Reference from 9V Battery
551902
LM385-2.5 Applications
Micropower 5V Reference
551909
Note 10: IQ ≃ 40 μA
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LM185-2.5/LM285-2.5/LM385-2.5
Micropower 10V Reference
551910
Note 11: IQ ≃ 30 μA standby current
PRECISION 1 μA to 1 mA CURRENT SOURCES
551924
551925
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LM185-2.5/LM285-2.5/LM385-2.5
METER THERMOMETERS
0°C–100°C Thermomemter
551926
Calibration
1. Short LM385-2.5, adjust R3 for IOUT=temp at 1μA/°K
Remove short, adjust R2 for correct reading in centigrade
0°F–50°F Thermomemter
551927
Calibration
1. Short LM385-2.5, adjust R3 for IOUT=temp at 1.8 μA/°K
Remove short, adjust R2 for correct reading in °F
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LM185-2.5/LM285-2.5/LM385-2.5
Micropower Thermocouple Cold Junction Compensator
551906
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.
Seebeck Voltage Voltage
Thermocouple Co- R1 R2 Across R1 Across R2
Type efficient (Ω) (Ω) @25°C (mV)
(μV/°C) (mV)
J 52.3 523 1.24k 15.60 14.32
T 42.8 432 1k 12.77 11.78
K 40.8 412 953Ω 12.17 11.17
S 6.4 63.4 150Ω 1.908 1.766
Typical supply current 50 μA
Improving Regulation of Adjstable Regulators
551907
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LM185-2.5/LM285-2.5/LM385-2.5
Schematic Diagram
551901
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LM185-2.5/LM285-2.5/LM385-2.5
Physical Dimensions inches (millimeters) unless otherwise noted
Order Number LM185E-2.5/883
NS Package Number E20A
TO-46 Metal Can Package (H)
Order Number LM185H-2.5, LM185H-2.5/883, LM185BXH-2.5, LM185BXH-2.5/883,
LM185BYH-2.5, LM185BYH-2.5/883, LM285H-2.5, or LM285BYH-2.5
NS Package Number H02A
11 www.national.com
LM185-2.5/LM285-2.5/LM385-2.5
SOT-23 Package (M3)
Order Number LM385M3-2.5
NS Package Number MA03B
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LM185-2.5/LM285-2.5/LM385-2.5
Small Outline (SO-8) Package (M)
Order Number LM285M-2.5, LM285BXM-2.5, LM285BYM-2.5,
LM385M-2.5, LM385BM-2.5, LM385BXM-2.5 or LM385BYM-2.5
NS Package Number M08A
13 www.national.com
LM185-2.5/LM285-2.5/LM385-2.5
TO-92 Plastic Package (Z)
Order Number LM285Z-2.5, LM285BXZ-2.5, LM285BYZ-2.5,
LM385Z-2.5, LM385AXZ-2.5, LM385AYZ-2.5,
LM385BZ-2.5, LM385BXZ-2.5 or LM385BYZ-2.5
NS Package Number Z03A
www.national.com 14
LM185-2.5/LM285-2.5/LM385-2.5
Notes
15 www.national.com
LM185-2.5/LM285-2.5/LM385-2.5
Notes
LM185-2.5/LM285-2.5/LM385-2.5 Micropower Voltage Reference Diode
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