LM285BXZ-1.2/NOPB - National Semiconductor

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

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,

(Note 6) (Note 5) (Note 6) (Note 5) (Note 6)

Reverse Breakdown TA = 25°C, 1.23

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

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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

Seebeck R1 R2 Voltage Voltage

Type Coefficient (Ω) (Ω) Across

Across

(μV/°C) @ 25°C (mV)

(mV)

J 52.3 52

1.2

15.60 14.32

T 42.8 43

1k 12.77 11.78

K 40.8 41

3Ω

12.17 11.17

S 6.4 63.

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

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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

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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

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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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