LM385/LM385B
Adjustable Micropower Voltage Reference
Analog Integrations Corporation 4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan
DS-385B-01 012102
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
1
n
FEATURES
l
Adjustable from 1.24V to 5.3V.
l
Operating Current from 10
A to 20mA.
l
Low Temperature Coefficient.
l
1% and 2% Initial Tolerance.
l
Low Dynamic Impedance.
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APPLICATIONS
l
Portable, Battery-Powered Equipment.
l
Instrumentation.
l
Process Control.
l
Energy Management.
l
Product Testing.
l
Automotive.
l
Precision Audio Components.
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TYPICAL APPLICATION
CIRCUIT
1.24V
FB
-
R
S
V
IN
LM385
+
I
R
Precision 1.24V Voltage Reference
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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 10
A 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
circuitry with battery life approaching shelf life.
Further, the wide operating current allows it to
replace older references with a tighter tolerance
part.
LM385/LM385B
2
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ORDERING INFORMATION
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%
LM385X-CXXX
Example: LM385-CXTR
2% version, in SOT-89 Package & Taping &
Reel Packing Type
(CS is not available in BAG packing type.)
PIN CONFIGURATION
NC
1
3
4
2
8
6
5
7
+
NC
NC
-
NC
FB
NC
SO-8
TOP VIEW
1
2
3
SOT-89
TOP VIEW
1: FB
2:
-
3: +
1
2
3
TO-92
TOP VIEW
1: FB
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)
..................... ... ... ... ... ... ..... ... ................
260
C
SO Package Vapor phase (60 seconds) ............... ... ... ... ... ... ... ... ........................
215
C
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TEST CIRCUIT
Refer to TYPICAL APPLICATION CIRCUIT.
LM385/LM385B
3
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ELECTRICAL CHARACTERISTICS
(T
A
=25
C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
SYMBOL
MIN.
TYP.
MAX.
UNIT
Reverse Voltage
I
R
=100
A
LM385B
LM385
V
R
1.228
1.215
1.240
1.240
1.252
1.265
V
Reverse Voltage Change with
Current
I
RMIN
I
R
1mA
1mA
I
R
20mA
V
R
0.2
5
1
15
mV
Minimum Operating Current
V
OUT
=1.24V
V
OUT
=5.3V
I
RMIN
7
35
11
55
A
Dynamic Output Impedance
I
R
=100
A, f=100Hz
I
AC
=0.1I
R
, V
OUT
=1.24V,
V
OUT
=5.3V
Z
R
0.4
1
Reference Voltage Change with
Output Voltage
I
R
=100
A
2
5
mV
Feedback Current
I
FB
8
20
nA
Output Wideband Noise
I
R
=100
A, 10Hz<f<10KHz
V
OUT
=1.24V,
V
OUT
=5.3V
e
N
50
170
V
RMS
Average Temperature
Coefficient (Note)
I
R
=100
A
V
R
100
ppm/
C
Long Term Stability
I
R
=100
A, T=1000Hrs,
T
A
=25
C
0.1
C
V
R
/
t
20
ppm
Note : 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
0.01
0.1
1
10
100
0
0.2
0.4
0.6
0.8
1.0
Fig. 1 Forward characteristics
Forward Current (mA)
Forward Voltage (V)
TA= -55
C
TA= 25
C
TA= 125
C
Fig. 2 Reverse Characteristics
Reverse Current (
A)
100
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0.1
1
10
TA= -55
C
TA= 25
C
TA= 125
C
Reverse Voltage (V)
LM385/LM385B
4
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TYPICAL PERFORMANCE CHARACTERISTICS
(Continued)
Fig. 3 Temperature Drift of 3 Representative Units
Temperature (
C)
Reference voltage (V)
1.21
1.23
1.25
1.27
125
I
R
=100
A
50
100
-50
0
Fig. 4 Reverse Characteristics
Output Voltage Change (mV)
Reverse Current (mA)
0.01
0.1
1
10
100
0
1
2
3
4
5
TA= -55
C
TA= 80
C
TA= 25
C
Minimum Current (
A)
Output Voltage (V)
Fig. 5 Minimum Operating Current
1
2
3
4
5
6
0
20
40
60
80
Fig. 6 Feedback Current
Feedback Current (nA)
Temperature (
C)
0
20
40
60
80
100
120
-20
0
2
4
6
8
10
V
OUT
=V
REF
V
OUT
=5.3V
I
R
=100
A
Voltage (V)
Time (
S)
Fig. 7 Response Time
0
50
100
150
200
250
-50
0
1
2
3
4
5
10
0
Output
120K
364K
-
+
V
OUT
50K
Input
Input
Fig. 8 Output Noise Voltage (
nV / Hz
)
Noise
10K
Frequency (Hz)
10
100
1K
10K
100K
10
100
1K
V
OUT
= V
REF
I
R
=100
A
V
OUT
=5.3V
LM385/LM385B
5
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BLOCK DIAGRAM
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SYMBOL
-
+
-
+
7
A
1.2
FB
-
+
FB
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PIN DESCRIPTIONS
PIN +
-
sinks current with a range from 20
A to 20mA for normal applications. And a stable positive voltage,
relative to Pin-, occurs on Pin+.
PIN -
-
Pin- sources current for normal application. The current value is the same as Pin+.
PIN NC -
Not connected.
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APPLICATION EXAMPLES
120K
R2
120K
R1
-
+
LM385
2N2219
R3
1K
50
A<I<200mA
V
IN
FB
V
OUT
2.5V
R4
100
A<I<5mA
V
IN
FB
-
+
R3
LM385
2N5115
2.4M
R2
120K
R1
V
OUT
25V
Fig. 9 200mA Shunt Regulator
Fig. 10 25V Low Current Shunt Regulator
R2
R1
1
A<I
OUT
<100mA
I
OUT
=1.24V/R1
2N2905
2N3964
FB
-
+
120K
V
IN
R3
200
D1
<-12V
LED ON
R2
1M
FB
120K
R1
-5V
-
+
Fig. 11 Current Source
Fig. 12 Voltage Level Detector
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