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 10 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 LM185-1.2 band-gap reference uses only transis-
tors and resistors, low noise and good long term stability re-
sult.

Careful design of the LM185-1.2 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 LM185-1.2 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 car-
rier package.

Features

4 mV (

0.3%) max. initial tolerance (A grade)

Operating current of 10 µA to 20 mA

0.6

max dynamic impedance (A grade)

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)

DS005518-10

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

DS005518-33

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 MA03B

January 2000

LM185-1.2/LM285-1.2/LM385-1.2

Micropower

oltage

Reference

Diode

DS005518

www.national.com

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

30 mA

Forward Current

10 mA

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

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

(Notes

5, 8)

(Note 6)

(Note 5)

(Note 6)

(Note 5)

(Note 6)

Reverse Breakdown

= 25°C,

1.235

1.223

1.205

V(Min)

Voltage

10 µA

20 mA

1.247

1.260

V(Max)

Minimum Operating

µA

Current

LM385M3-1.2

(Max)

Reverse Breakdown

10 µA

1 mA

1.5

Voltage Change

(Max)

with Current

1 mA

20 mA

(Max)

Reverse Dynamic

= 100 µA, f = 20 Hz

Impedance

Wideband Noise

= 100 µA,

µV

(rms)

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-1.2 for military specifications.

Note 3: For elevated temperature operation, T

max is:

LM185

150°C

LM285

125°C

LM385

100°C

Thermal Resistance

TO-92

TO-46

SO-8

SOT23

(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.

LM185-1.2/LM285-1.2/LM385-1.2

www.national.com

Electrical Characteristics

(Note 4) (Continued)

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

- T

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 is available on request.

Typical Performance Characteristics

Reverse Characteristics

DS005518-13

Reverse Characteristics

DS005518-14

Forward Characteristics

DS005518-15

Temperature Drift of 3
Representative Units

DS005518-16

Reverse Dynamic Impedance

DS005518-17

Reverse Dynamic Impedance

DS005518-18

Noise Voltage

DS005518-19

Filtered Output Noise

DS005518-20

Response Time

DS005518-21

LM185-1.2/LM285-1.2/LM385-1.2

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