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-terminal band-gap voltage regulator diodes. Operating over a 20
μA to 20 mA current range, they feature exceptionally low dynamic 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 resistors, low noise and good long term stability result.
Careful design of the LM185-2.5 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 LM185-2.5 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. Further, the wide operating current allows it to replace older
references with a tighter tolerance part. For applications requiring 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
LM185-2.5/LM285-2.5/LM385-2.5 Micropower Voltage Reference Diode
January 30, 2008
Connection Diagrams
TO-92
Plastic Package
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
* Pin 3 is attached to the Die Attach Pad (DAP) and should be connected to Pin 2 or left floating.
551908
SOT-23
551929
Order Number LM385M3-2.5
See NS Package Number MA03B
SO Package
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
551911
© 2008 National Semiconductor Corporation 5519 www.national.com
Leadless Chip Carrier
LCC
TO-46
Metal Can Package
LM185-2.5/LM285-2.5/LM385-2.5
Order Number LM185E-2.5/883
See NS Package Number E20A
551914
Bottom View
551913
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
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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)
LM385A-2.5
LM385AX-2.5
Parameter Conditions Typ
Reverse Breakdown
Voltage 2.520 V(Max)
2.500 2.470 V(Min)
2.530 V(Max)
Minimum Operating
Current (Max)
Reverse Breakdown
Voltage Change with (Max)
Current
(Max)
Reverse Dynamic
Impedance f = 20 Hz 1.5
Wideband Noise (rms)
Long Term Stability
T = 1000 Hr, 20 ppm
TA = 25°C ±0.1°C
Average Temperature
Coefficient (Note 7) X Suffix 30 ppm/°C
Y Suffix 50 (Max)
All Others 150
IR = 100 μA
I
≤ IR ≤ 1mA
MIN
1 mA ≤ IR ≤ 20 mA
IR = 100 μA,
IR = 100 μA
10 Hz ≤ f ≤ 10 kHz
IR = 100 μA,
I
≤ IR ≤ 20 mA
MIN
2.500 2.480 V(Min)
12 18 20
1 1.5 mV
10 20 mV
0.2
120
LM385AY-2.5
Tested Design
Limit Limit
(Note 5) (Note 6)
0.6
Units
(Limits)
μA
Ω
μV
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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
Limit Limit Limit Limit Limit Limit
Reverse
Breakdown
LM185-2.5/LM285-2.5/LM385-2.5
Voltage
Minimum Operating
Current
Reverse
TA = 25°C, 2.5 2.462 2.462 2.425 V(Min)
20 μA ≤ IR ≤ 20 mA
2.538 2.538 2.575 V(Max)
13 20 30 20 30 20 30
LM385M3-2.5 15 20
20 μA ≤ IR ≤ 1 mA
1 1.5 2.0 2.5 2.0 2.5 mV
Breakdown Voltage
Change with
1 mA ≤ IR ≤ 20 mA
10 20 20 25 20 25 mV
Current
Reverse Dynamic
IR = 100 μA,
1
Impedance f = 20 Hz
Wideband Noise
(rms)
Long Term Stability
IR = 100 μA,
10 Hz ≤ f ≤ 10 kHz
IR = 100 μA,
120
T = 1000 Hr, 20 ppm
TA = 25°C ±0.1°C
Average
IR = 100 μA
Temperature
Coefficient (Note 7) X Suffix 30 30 ppm/°C
Y Suffix 50 50 ppm/°C
All Others 150 150 150 ppm/°C
(Max)
Tested Design Tested Design Tested Design
(Notes 5, 8) (Note 6) (Note 5) (Note 6) (Note 5) (Note 6)
μA
(Max)
(Max)
(Max)
Ω
μV
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, T
LM185 150°C
LM285 125°C
LM385 100°C
Thermal Resistance TO-92 TO-46 SO-8 SOT-23
θja (Junction to Ambient)
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 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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, divided by T
MIN
. The measured temperatures are −55°C, −40°C, 0°C, 25°C, 70°C, 85°C, 125°C.
MAX–TMIN
is:
J MAX
180°C/W (0.4″ Leads) 440°C/W 165°C/W 283°C/W
170°C/W (0.125″ Leads)
N/A 80°C/W N/A N/A
Typical Performance Characteristics
LM185-2.5/LM285-2.5/LM385-2.5
Reverse Characteristics
Forward Characteristics
551915
Reverse Characteristics
551916
Temperature Drift
Reverse Dynamic
Impedance
551917
551919
551918
Reverse Dynamic
Impedance
551920
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Noise Voltage
LM185-2.5/LM285-2.5/LM385-2.5
Filtered Output Noise
Applications
Wide Input Range Reference
Response Time
551921
551923
551922
LM385-2.5 Applications
Micropower 5V Reference
551912
Micropower Reference from 9V Battery
551902
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Note 10: IQ ≃ 40 μA
551909
Micropower 10V Reference
LM185-2.5/LM285-2.5/LM385-2.5
Note 11: IQ ≃ 30 μA standby current
PRECISION 1 μA to 1 mA CURRENT SOURCES
551910
551925
551924
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METER THERMOMETERS
LM185-2.5/LM285-2.5/LM385-2.5
Calibration
Short LM385-2.5, adjust R3 for I
1.
Remove short, adjust R2 for correct reading in centigrade
=temp at 1μA/°K
OUT
0°C–100°C Thermomemter
551926
0°F–50°F Thermomemter
Calibration
Short LM385-2.5, adjust R3 for I
1.
Remove short, adjust R2 for correct reading in °F
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=temp at 1.8 μA/°K
OUT
551927
Micropower Thermocouple Cold Junction Compensator
551906
Adjustment Procedure
Adjust TC ADJ pot until voltage across R1 equals Kelvin temperature multiplied by the thermocouple Seebeck coefficient.
1.
Adjust zero ADJ pot until voltage across R2 equals the thermocouple Seebeck coefficient multiplied by 273.2.
2.
Seebeck Voltage Voltage
Thermocouple Co- R1 R2 Across R1 Across R2
Type efficient
(μV/°C)
(Ω) (Ω)
(mV)
@25°C
(mV)
J 52.3 523 1.24k 15.60 14.32
T 42.8 432 1k 12.77 11.78
Typical supply current 50 μA
K 40.8 412
S 6.4 63.4
953Ω
150Ω
12.17 11.17
1.908 1.766
LM185-2.5/LM285-2.5/LM385-2.5
Improving Regulation of Adjstable Regulators
551907
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Schematic Diagram
LM185-2.5/LM285-2.5/LM385-2.5
551901
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Physical Dimensions inches (millimeters) unless otherwise noted
LM185-2.5/LM285-2.5/LM385-2.5
Order Number LM185E-2.5/883
NS Package Number E20A
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
TO-46 Metal Can Package (H)
NS Package Number H02A
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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
Order Number LM285M-2.5, LM285BXM-2.5, LM285BYM-2.5,
LM385M-2.5, LM385BM-2.5, LM385BXM-2.5 or LM385BYM-2.5
Small Outline (SO-8) Package (M)
NS Package Number M08A
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LM185-2.5/LM285-2.5/LM385-2.5
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
TO-92 Plastic Package (Z)
NS Package Number Z03A
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Notes
LM185-2.5/LM285-2.5/LM385-2.5
15 www.national.com
Notes
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LM185-2.5/LM285-2.5/LM385-2.5 Micropower Voltage Reference Diode
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