LM185-2.5 (Linear Technology)
Micropower Voltage Reference

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FEATURES
s 20µA to 20mA Operating Range
s Guaranteed 1% Initial Voltage Tolerance
s Guaranteed 1Dynamic Impedance
s Very Low Power Consumption
U
APPLICATIO S
s Portable Meter References
s Portable Test Instruments
s Battery-Operated Systems
s Panel Meters
s Current Loop Instrumentation
LM185-2.5/
LM285-2.5/LM385-2.5
Micropower Voltage
Reference
DESCRIPTIO
The LM185-2.5 is a two-terminal band gap reference
diode that has been designed for applications which
require precision performance with micropower opera-
tion. The device provides guaranteed operation specifica-
tions at currents as low as 20µA. The nominal voltage is
2.5V with both 1% and 2% tolerances available. Some
additional features are: maximum dynamic impedance of
1, low noise and excellent stability over time and tem-
perature. The advanced design, processing and testing
techniques make Linear’s LM185-2.5 a superior choice
over previous designs. A circuit for cold junction compen-
sation of a thermocouple is shown below.
For applications requiring guaranteed temperature drift,
see the LT1034 data sheet.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Thermocouple Cold Junction Compensator
IQ 50µA
2 MERCURY
CELLS 2.6V
16k
1M
LM385-2.5
TYPE K
100k W.W.
ZERO
950
+
METER
VIN
LM334
RSET
V
2k
450
10k ADJUST
FOR 12.17mV
AT 25°C
ACROSS 450
LM185-2.5 TA01
Reverse Voltage Change
16
–55°C TA +125°C
12
8
4
0
–4
0.01
0.1 1
10
REVERSE CURRENT (mA)
100
LM185-2.5 TA02
1


LM185-2.5 (Linear Technology)
Micropower Voltage Reference

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LM185-2.5/
LM285-2.5/LM385-2.5
ABSOLUTE AXI U RATI GS (Note 1)
Reverse Breakdown Current ................................ 30mA
Forward Current .................................................. 10mA
Operating Temperature Range
LM185-2.5 (OBSOLETE) ............ –55°C to 125°C
LM285-2.5 ...................................... – 40°C to 85°C
LM385-2.5 ........................................... 0°C to 70°C
Storage Temperature Range
LM185-2.5 (OBSOLETE) ............ – 65°C to 150°C
LM285-2.5 .................................... – 65°C to 150°C
LM385-2.5 .................................... – 65°C to 150°C
Lead Temperature (Soldering, 10 sec.)................ 300°C
PACKAGE/ORDER I FOR ATIO
BOTTOM VIEW
ORDER PART
NUMBER
H PACKAGE
2-LEAD TO-46 METAL CAN
TJMAX = 150°C, θJA = 440°C/W, θJC = 80°C/W
LM185H-2.5
LM285H-2.5
LM385H-2.5
LM385BH-2.5
(NOTE 3)
OBSOLETE PACKAGE
Consider the S8 or Z Packages for Alternate Source
TOP VIEW
NC 1
NC 2
8
7 NC
NC 3
6
45
S8 PACKAGE
8-LEAD PLASTIC SO
NC
(DO NOT
USE)
TJMAX = 150°C, θJA = 220°C/W
BOTTOM VIEW
Z PACKAGE
3-LEAD TO-92 PLASTIC
TJMAX = 100°C, θJA = 160°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ORDER PART
NUMBER
LM285Z-2.5
LM385Z-2.5
LM385BZ-2.5
(NOTE 3)
ORDER PART
NUMBER
LM285S8-2.5
LM385S8-2.5
LM385BS8-2.5
S8 PART MARKING
2852
3852
3852B
2


LM185-2.5 (Linear Technology)
Micropower Voltage Reference

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LM185-2.5/
LM285-2.5/LM385-2.5
ELECTRICAL CHARACTERISTICS The q denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2)
SYMBOL PARAMETER
CONDITIONS
LM185-2.5/285-2.5
MIN TYP MAX
LM385-2.5/385B-2.5
MIN TYP MAX
UNITS
VZ
Reverse Breakdown Voltage
TA = 25°C, 20µA IR 20mA
LM185-2.5/285-2.5
2.462 2.500 2.538
LM385-2.5
2.425 2.500 2.575
LM385B-2.5 (Note 3)
2.462 2.500 2.538
V
V
V
VZ
Temp
Average Temperature Coefficient
20µA IR 20mA (Note 3)
20
20 ppm/°C
IMIN Minimum Operating Current
VZ Reverse Breakdown Voltage
IR Change With Current
rZ Reverse Dynamic Impedance
en
VZ
Time
Wide Band Noise (RMS)
Long Term Stability
TMIN TA TMAX
20µA IR 1mA
TA = 25°C
TMIN TA TMAX
1mA IR 20mA
TA = 25°C
TMIN TA TMAX
IR = 100µA (Note 4)
TA = 25°C
TMIN TA TMAX
10Hz f 10kHz, IR = 100µA
TA = 25°C ± 0.1°C, IR = 100µA
q
q
q
q
8 20
1.0
1.5
10
20
0.2 0.6
1.5
120
20
8 20
2.0
2.5
20
25
0.4 1.0
1.5
120
20
µA
mV
mV
mV
mV
µV
ppm/kHr
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: All specifications are for TA = 25°C unless otherwise noted. For the
LM185-2.5 TMIN = – 55°C and TMAX = 125°C. For LM285-2.5, TMIN = –
40°C and TMAX = 85°C. For LM385-2.5, TMIN = 0°C and TMAX = 70°C.
Note 3: For very low initial tolerance, consult LT1004 data sheet. The
LT1004 is a low cost, pin for pin substitution device. For guaranteed
temperature coefficient consult the LT1034-2.5 data sheet.
Note 4: Guaranteed but not tested.
3


LM185-2.5 (Linear Technology)
Micropower Voltage Reference

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LM185-2.5/
LM285-2.5/LM385-2.5
TYPICAL PERFOR A CE CHARACTERISTICS
Reverse Characteristics
100
–55°C TO 125°C
10
1
0.1
0
0.5 1.0 1.5 2.0 2.5 3.0
REVERSE VOLTAGE (V)
LM185-2.5 • TPC01
Forward Characteristics
1.6
TA = 25°C
1.2
0.8
0.4
0
0.01
0.1 1
10
FORWARD CURRENT (mA)
100
LM185-2.5 • TPC02
Temperature Drift
2.525
2.520
2.515
2.510
2.505
2.500
2.495
2.490
2.485
2.480
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
LM185-2.5 • TPC03
Reverse Dynamic Impedance
1000
f = 25Hz
–55°C TO 125°C
100
10
1
0.1
0.01
0.1 1
10
REVERSE CURRENT (mA)
100
LM185-2.5 • TPC05
Reverse Dynamic Impedance
10k
TA = 25°C
IR = 100µA
1k
100
10
1
0.1
10
100 1k 10k 100k
FREQUENCY (Hz)
1M
LM185-2.5 • TPC05
Noise Voltage
1400
1200
1000
800
600
400
200
0
10 100 1k 10k 100k
FREQUENCY (Hz)
LM185-2.5M • TPC06
Filtered Output Noise
120
100mA
100 R
C
80
Response Time
4.0
3.0
60
40
20
0
100
RC LOW PASS
1k 10k 100k
CUTOFF FREQUENCY (Hz)
LM185-2.5 • TPC07
2.0 OUTPUT
1.0
24k
VIN
VOUT
0
5V
0
0
INPUT
100
TIME (µS)
500
LM185-2.5 • TPC08
4


LM185-2.5 (Linear Technology)
Micropower Voltage Reference

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SCHE ATIC DIAGRA
LM185-2.5/
LM285-2.5/LM385-2.5
7.5k Q13
Q4 Q12
Q3 Q7
20pF 20pF Q11
Q1 600k
Q10
Q2
100k
Q5
Q6
500
60k
Q8
Q9
+
200k
50k 500k
300k
Q14
500k
LM185-2.5 SD01
PACKAGE DESCRIPTIO
0.209 – 0.219
(5.309 – 5.537)
0.178 – 0.195
(4.521 – 4.953)
REFERENCE
PLANE
0.500
(12.700)
MIN
0.016 – 0.021**
(0.406 – 0.533)
DIA
H Package
2-Lead and 3-Lead TO-46 Metal Can
(Reference LTC DWG # 05-08-1340)
0.085 – 0.105
(2.159 – 2.667)
*
0.025
(0.635)
MAX
0.050
(1.270)
TYP
0.100
(2.540)
TYP
PIN 1
45°
0.036 – 0.046
(0.914 – 1.168)
0.050
(1.270)
TYP
FOR 3-LEAD PACKAGE ONLY
0.028 – 0.048
(0.711 – 1.219)
H02/03(TO-46) 1098
*LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE
AND 0.045" BELOW THE REFERENCE PLANE
**FOR
SOLDER
DIP
LEAD
FINISH,
LEAD
DIAMETER
IS
0.016
(0.406
0.024
0.610)
OBSOLETE PACKAGE
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Micropower Voltage Reference

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LM185-2.5/
LM285-2.5/LM385-2.5
PACKAGE DESCRIPTIO
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
8 765
0.228 – 0.244
(5.791 – 6.197)
0.150 – 0.157**
(3.810 – 3.988)
0.010
(0.254
0.020
0.508)
×
45°
0.008 – 0.010
(0.203 – 0.254)
12
0.053 – 0.069
(1.346 – 1.752)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
34
SO8 1298
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
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Micropower Voltage Reference

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PACKAGE DESCRIPTIO
LM185-2.5/
LM285-2.5/LM385-2.5
Z Package
3-Lead Plastic TO-92 (Similar to TO-226)
(Reference LTC DWG # 05-08-1410)
0.060 ± 0.005
(1.524± 0.127)
DIA
0.180 ± 0.005
(4.572 ± 0.127)
0.500
(12.70)
MIN
0.050
(1.27)
BSC
0.180 ± 0.005
(4.572 ± 0.127)
0.90
(2.286)
NOM
0.050 UNCONTROLLED
(1.270) LEAD DIMENSION
MAX
5°
NOM
0.016 ± 0.003
(0.406 ± 0.076)
0.060 ± 0.010
(1.524 ± 0.254)
0.140 ± 0.010
(3.556 ± 0.127)
0.015 ± 0.002
(0.381 ± 0.051)
0.098 +016/–0.04
(2.5 +0.4/–0.1)
2 PLCS
Z3 (TO-92) 0401
TO-92 TAPE AND REEL
REFER TO TAPE AND REEL SECTION OF
LTC DATA BOOK FOR ADDITIONAL INFORMATION
10° NOM
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of circuits as described herein will not infringe on existing patent rights.
7


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Micropower Voltage Reference

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LM185-2.5/
LM285-2.5/LM385-2.5
TYPICAL APPLICATI S
9V
220k
2.5V
LM385-2.5
REFERENCE FROM
A 9V BATTERY
V+
3.7V V+ 30V
LM334
R
2.7k
2.5V
LM385-2.5
OPERATION OVER A
WIDE SUPPLY RANGE
LM185-2.5 TA03
RELATED PARTS
PART NUMBER
LT1634
DESCRIPTION
Micropower Shunt Voltage Reference
COMMENTS
0.05% Initial Accuracy, 10ppm/°C Maximum Tempco
Output Voltage: 1.25V, 2.5V, 4.096V and 5V
8 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507 q www.linear.com
185fc LT/CP 0801 1.5K REV C • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 1992




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