LM385/LM385B
Adjustable Micropower Voltage Reference
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FEATURES
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DESCRIPTION
The LM385 is micropower 3-terminal adjustable
band-gap voltage reference. Operating from
1.24V to 5.3V and over 10µA to 20mA current
range. They feature exceptionally low dynamic
impedance and good temperature stability. On-
chip trimming is used to achieve tight voltage
tolerance. Since the LM385 band-gap reference
uses only transistors and resistors, low noise
and good longterm stability result.
Careful design of the LM385 has made the de-
vice 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 LM385
makes it useful for micropower circuitry. This
voltage reference can be used to make portable
meters, regulators or general purpose analog
1.24V
Adjustable from 1.24V to 5.3V.
Operating Current from 10µA to 20mA.
Low Temperature Coefficient.
1% and 2% Initial Tolerance.
Low Dynamic Impedance.
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APPLICATIONS
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Portable, Battery-Powered Equipment.
Instrumentation.
Process Control.
Energy Management.
Product Testing.
Automotive.
Precision Audio Components.
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TYPICAL APPLICATION
CIRCUIT
V
IN
R
S
circuitry with battery life approaching shelf life.
Further, the wide operating current allows it to
replace older references with a tighter tolerance
part.
+
LM385
I
R
FB
-
Precision 1.24V Voltage Reference
Analog Integrations Corporation
4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
DS-385B-01 012102
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LM385/LM385B
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ORDERING INFORMATION
LM385X-CXXX
PACKING TYPE
BG: BAG
TR: TAPE & REEL
TB: TUBE (for SO-8)
PACKAGE TYPE
X: SOT-89
Z: TO-92
S: SMALL OUTLINE
TOLERANCE
Default: 2%
B: 1%
Example: LM385-CXTR
à
2% version, in SOT-89 Package & Taping &
Reel Packing Type
(CS is not available in BAG packing type.)
PIN CONFIGURATION
SOT-89
TOP VIEW
1: FB
2:
-
3: +
1
2
3
TO-92
TOP VIEW
1: FB
2: +
3:
-
SO-8
TOP VIEW
NC
NC
NC
1
2
3
4
8
7
6
5
+
NC
NC
FB
1
2
3
-
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ABSOLUTE MAXIMUM RATINGS
Reverse Current
....… ................................… … … … … ............................................
30mA
Forward Current
… … … ....................................… ..… … … … .....................................10mA
Operating Temperature Range.
.… … … … … … … … .… … … ................… ........
0°C to 70°C
Storage Temperature
...................................… … .… … … … .......................
-65°C to 150°C
Lead Temperature
TO-92 Package Soldering (10 seconds)
SO Package Vapor phase (60 seconds)
..................… … … … … … ..… … ................
260°C
............… … … … … … … … ........................
215°C
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TEST CIRCUIT
Refer to TYPICAL APPLICATION CIRCUIT.
2
LM385/LM385B
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ELECTRICAL CHARACTERISTICS
(T =25°C, unless otherwise specified.)
A
PARAMETER
Reverse Voltage
Reverse Voltage Change with
Current
Minimum Operating Current
TEST CONDITIONS
I
R
=100µA
I
RMIN
≤I
R
≤1mA
1mA≤I
R
≤20mA
V
OUT
=1.24V
V
OUT
=5.3V
I
R
=100µA, f=100Hz
I
AC
=0.1I
R
, V
OUT
=1.24V,
V
OUT
=5.3V
LM385B
LM385
SYMBOL
MIN.
TYP.
1.240
1.240
0.2
5
7
MAX.
1.252
1.265
1
15
11
55
UNIT
V
V
R
1.228
1.215
∆V
R
mV
µA
I
RMIN
35
Dynamic Output Impedance
Reference Voltage Change with
Output Voltage
Feedback Current
Z
R
0.4
1
2
5
20
Ω
I
R
=100µA
I
FB
I
R
=100µA, 10Hz<f<10KHz
mV
nA
8
Output Wideband Noise
Average Temperature
Coefficient (Note)
Long Term Stability
Note :
V
OUT
=1.24V,
V
OUT
=5.3V
I
R
=100µA
I
R
=100µA, T=1000Hrs,
T
A
=25°C±0.1°C
e
N
αV
R
∆V
R
/∆t
50
170
100
20
µV
RMS
ppm/°C
ppm
The average temperature coefficient is defined as the maximum deviation of reverse voltage at all
measured temperatures from T
MIN
to T
MAX
, divided by T
MAX
- T
MIN
. The measured temperatures are
0°C, 25°C, 50°C and 70°C.
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TYPICAL PERFORMANCE CHARACTERISTICS
1.0
100
Forward Voltage (V)
0.8
TA= -55
°
C
TA= 25
°
C
Reverse Current (
µA)
10
0.6
TA= 125
°
C
TA= -55
°
C
0.4
TA= 25
°
C
1
TA= 125
°
C
0.2
0
0.1
0.01
0.1
1
10
100
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Forward Current (mA)
Fig. 1 Forward characteristics
Reverse Voltage (V)
Fig. 2 Reverse Characteristics
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LM385/LM385B
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TYPICAL PERFORMANCE CHARACTERISTICS
(Continued)
1.27
5
Output Voltage Change (mV)
I
R
=100
µ
A
Reference voltage (V)
4
1.25
3
2
1.23
TA= 25
°
C
1
TA= -55
°
C
TA= 80
°
C
1.21
-50
0
50
100
125
0
0.01
0.1
1
10
100
Temperature (
°
C)
Fig. 3 Temperature Drift of 3 Representative Units
Reverse Current (mA)
Fig. 4 Reverse Characteristics
80
10
I
R
=100
µ
A
Minimum Current (µA)
60
Feedback Current (nA)
8
6
V
OUT
=V
REF
4
40
V
OUT
=5.3V
20
2
0
1
2
3
4
5
6
0
-20
0
20
40
60
80
100
120
Output Voltage (V)
Fig. 5 Minimum Operating Current
Temperature (
°
C)
Fig. 6 Feedback Current
10K
5
V
OUT
=5.3V
4
I
R
=100
µ
A
Input
Voltage (V)
3
2
1
0
10
Output
50K
+
120K
1K
-
364K
Noise
V
OUT
V
OUT
= V
REF
100
Input
0
-50
0
10
150
200
250
Time (
µ
S)
Fig. 7 Response Time
50
100
10
100
1K
10K
100K
Frequency (Hz)
Fig. 8 Output Noise Voltage (
nV / Hz
)
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LM385/LM385B
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BLOCK DIAGRAM
+
1.2
+
FB
7
µ
A
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SYMBOL
+
-
FB
-
-
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PIN DESCRIPTIONS
PIN +
PIN -
-
-
sinks current with a range from 20µA to 20mA for normal applications. And a stable positive voltage,
relative to Pin-, occurs on Pin+.
Pin- sources current for normal application. The current value is the same as Pin+.
Not connected.
PIN NC -
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APPLICATION EXAMPLES
V
IN
R4
50µA<I<200mA
V
OUT
2.5V
LM385
R2
120K
V
IN
R3
100
µ
A<I<5mA
V
OUT
25V
+
LM385
-
2N2219
FB
R1
120K
+
FB
R1
120K
R2
2.4M
-
R3
1K
2N5115
Fig. 9 200mA Shunt Regulator
V
IN
+
R1
FB
Fig. 10 25V Low Current Shunt Regulator
R1
120K
+
FB
-
2N2905
2N3964
R2
120K
1
µ
A<I
OUT
<100mA
I
OUT
=1.24V/R1
-
D1
R3
200
R2
1M
<-12V
LED ON
-5V
Fig. 11 Current Source
Fig. 12 Voltage Level Detector
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