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 exception-
ally 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 transis-
tors and resistors, low noise and good long term stability re-
sult.

Careful design of the LM185-2.5 has made the device ex-
ceptionally 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. Fur-
ther, the wide operating current allows it to replace older ref-
erences with a tighter tolerance part. For applications requir-
ing 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 car-
rier package.

Features

20 mV (

0.8%) max. initial tolerance (A grade)

Operating current of 20 µA to 20 mA

0.6

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

DS005519-8

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

DS005519-11

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

DS005519-29

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

December 1999

LM185-2.5/LM285-2.5/LM385-2.5

Micropower

oltage

Reference

Diode

DS005519

www.national.com

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

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

(Note 5)

(Note 6)

Reverse Breakdown

= 100 µA

2.500

2.480

V(Min)

Voltage

2.520

V(Max)

2.500

2.470

V(Min)

2.530

V(Max)

Minimum Operating

µA

Current

(Max)

Reverse Breakdown

MIN

1mA

1.5

Voltage Change with

(Max)

Current

1 mA

20 mA

(Max)

Reverse Dynamic

= 100 µA,

0.2

0.6

Impedance

f = 20 Hz

1.5

Wideband Noise (rms)

= 100 µA

120

µV

10 Hz

10 kHz

Long Term Stability

= 100 µA,

T = 1000 Hr,

ppm

= 25°C

0.1°C

Average Temperature

MIN

20 mA

Coefficient (Note 7)

X Suffix

ppm/°C

Y Suffix

(Max)

All Others

150

LM185-2.5/LM285-2.5/LM385-2.5

www.national.com

Electrical Characteristics

(Continued)

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

(Note 5)

(Note 8)

(Note 6)

(Note 5)

(Note 6)

(Note 5)

(Note 6)

Reverse Breakdown

= 25°C,

2.5

2.462

2.425

V(Min)

Voltage

20 µA

20 mA

2.538

2.575

V(Max)

Minimum Operating
Current

µA

(Max)

LM385M3-2.5

Reverse Breakdown
Voltage Change with
Current

20 µA

1 mA

1.5

2.0

2.5

2.0

2.5

(Max)

1 mA

20 mA

(Max)

Reverse Dynamic

= 100 µA,

Impedance

f = 20 Hz

Wideband Noise (rms)

= 100 µA,

120

µV

10 Hz

10 kHz

Long Term Stability

= 100 µA,

T = 1000 Hr,

ppm

= 25°C

0.1°C

Average Temperature

= 100 µA

Coefficient (Note 7)

X Suffix

ppm/°C

Y Suffix

ppm/°C

All Others

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 in-
tended 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

J MAX

is:

LM185

150°C

LM285

125°C

LM385

100°C

Thermal Resistance

TO-92

TO-46

SO-8

SOT-23

(Junction to Ambient)

180°C/W (0.4" Leads)

440°C/W

165°C/W

283°C/W

170°C/W (0.125" Leads)

(Junction to Case)

N/A

80°C/W

N/A

Note 4: Parameters identified with boldface type apply at temperature extremes. All other numbers apply at T

= T

= 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

MAX

and T

MIN

, divided by T

MAX

MIN

. 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.

LM185-2.5/LM285-2.5/LM385-2.5

www.national.com

Typical Performance Characteristics

Applications

LM385-2.5 Applications

Reverse Characteristics

DS005519-15

Reverse Characteristics

DS005519-16

Forward Characteristics

DS005519-17

Temperature Drift

DS005519-18

Reverse Dynamic
Impedance

DS005519-19

Reverse Dynamic
Impedance

DS005519-20

Noise Voltage

DS005519-21

Filtered Output Noise

DS005519-22

Response Time

DS005519-23

Wide Input Range Reference

DS005519-12

Micropower Reference from 9V Battery

DS005519-2

LM185-2.5/LM285-2.5/LM385-2.5

www.national.com

LM385-2.5 Applications

(Continued)

Seebeck

Voltage

Thermocouple

Co-

Across R1

Across R2

Type

efficient

(

)

(

)

25°C

(mV)

(

V/°C)

(mV)

52.3

523 1.24k

15.60

14.32

42.8

432

12.77

11.78

40.8

412 953

12.17

11.17

6.4

63.4 150

1.908

1.766

Typical supply current 50 µA

Micropower Thermocouple Cold Junction

Compensator

DS005519-6

Adjustment Procedure

Adjust TC ADJ pot until voltage across R1 equals Kelvin
temperature multiplied by the thermocouple Seebeck
coefficient.

Adjust zero ADJ pot until voltage across R2 equals the
thermocouple Seebeck coefficient multiplied by 273.2.

Improving Regulation of Adjstable Regulators

DS005519-7

LM185-2.5/LM285-2.5/LM385-2.5

www.national.com

Physical Dimensions

inches (millimeters) unless otherwise noted (Continued)

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NATIONAL'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or

systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.

2. A critical component is any component of a life

support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.

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www.national.com

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

LM185-2.5/LM285-2.5/LM385-2.5

Micropower

oltage

Reference

Diode

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LM185B-1.2

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LM185B-1.2