The AMS285-1.2/AMS385-1.2 are two-terminal micropower band-gap voltage reference diodes. They feature a very low
dynamic impedance and good temperature coefficient, operating over a 10µA to 20mA current range. On-chip trimming is
used to provide tight voltage tolerance. Since the AMS285-1.2/AMS385-1.2 is a band-gap reference, uses only transistors and
resistors, low noise and good long-term stability result. Careful design of the AMS285-1.2/AMS385-1.2 has made the device
exceptionally 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
AMS285-1.2/AMS385-1.2 makes these reference diodes useful for micropower circuitry. These voltage references can be
used to make portable meters, regulators or general purpose analog circuitry with battery life approaching shelf life. Further
more, the wide operating current allows it to replace older references with a tight tolerance part.
The AMS285-1.2 is operational in the full industrial temperature range of -40°C to 85°C while AMS385-1.2 is operating
over a 0°C to 70°C temperature range. The AMS285-1.2/AMS385-1.2 are available in TO-92, SO-8 and SOT-89 packages.
ORDERING INFORMATION
:
TOL.
±4mV
±12mV
±25mV
±4mV
±12mV
±25mV
TO-92
AMS285-1.2AN
AMS285-1.2BN
AMS285-1.2CN
AMS385-1.2AN
AMS385-1.2BN
AMS385-1.2CN
PACKAGE TYPE
8 LEAD SOIC
AMS285-1.2AS
AMS285-1.2BS
AMS285-1.2CS
AMS385-1.2AS
AMS385-1.2BS
AMS385-1.2CS
SOT-89
AMS285-1.2AL
AMS285-1.2BL
AMS285-1.2CL
AMS385-1.2AL
AMS385-1.2BL
AMS385-1.2CL
OPERATING
TEMPERATURE RANGE
-40 to 85° C
-40 to 85° C
-40 to 85° C
0 to 70° C
0 to 70° C
0 to 70° C
Advanced Monolithic Systems, Inc.
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS285-1.2/AMS385-1.2
ABSOLUTE MAXIMUM RATINGS
Reverse Current
Forward Current
Operating Temperature Range
AMS285-1.2
AMS385-1.2
30mA
10mA
-40°C to 85°C
0°C to 70°C
Storage temperature
Soldering information
TO-92 package: 10 sec.
SOIC package: Vapor phase (60 sec)
Infrared (15 sec.)
SOT-89 package: 10 sec.
-55°C to +150°C
260°C
215°C
220°C
265°C
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at I
R
= 100
µA,
and T
A
= +25°C unless otherwise specified.
Parameter
Reverse Breakdown
Voltage (Note 4)
Reverse Dynamic
Impedance (Note 4)
Reverse Breakdown
Voltage Change with
current (Note 4)
Min. Operating
Current (Note 4)
Wide Band Noise
(Note 5)
Temperature Coeff.
(Note 6)
Long Term Stability
(Note 5)
T
A
=25°C±.1°C
T = 1000 Hr
I
R
- 100
µA,
10Hz
≤
f
≤
10kHz
Conditions
I
R
- 100
µA
I
R
- 100
µA,
f =20Hz
10µA
≤I
R
≤1mA
1mA
≤I
R
≤20mA
AMS285A-1.2
Min
Typ
Max
1.231
1.235
0.2
1.0
10
8
10
20
1.239
0.60
AMS285B-1.2
Min
Typ
Max
1.223
1.235
1
1.0
10
8
10
20
1.247
AMS285C-1.2
Min
Typ
Max
1.205
1.235
1
1.0
20
8
15
25
1.260
Units
V
Ω
mV
µA
µA
µV
60
60
60
25
50
100
150
ppm/°C
20
20
20
ppm
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at I
R
= 100
µA,
and T
A
= +25°C unless otherwise specified.
Parameter
Reverse Breakdown
Voltage (Note 4)
Reverse Dynamic
Impedance (Note 4)
Reverse Breakdown
Voltage Change with
Current (Note 4)
Min. Operating
Current (Note 4)
Wide Band Noise
(Note 5)
Temperature Coeff.
(Note 6)
Long Term Stability
(Note 5)
T
A
=25°C±.1°C
T = 1000 Hr
I
R
- 100
µA,
10Hz
≤
f
≤
10kHz
Conditions
I
R
- 100
µA
I
R
- 100
µA,
f =20Hz
10µA
≤I
R
≤1mA
1mA
≤I
R
≤20mA
AMS385A-1.2
Min
Typ
Max
1.231
1.235
0.2
1.0
10
8
10
20
1.239
0.60
AMS385B-1.2
Min
Typ
Max
1.223
1.235
1
1.0
20
8
10
20
1.247
AMS385C-1.2
Min
Typ
Max
1.205
1.235
1
1.0
20
8
15
25
1.260
Units
V
Ω
mV
µA
µA
µV
60
60
60
25
50
100
150
ppm/°C
20
20
20
ppm
Advanced Monolithic Systems, Inc.
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS285-1.2/AMS385-1.2
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended 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:
For elevated temperature operation, T
j
max is:
AMS285
AMS385
+125°C
+100°C
Thermal Resistance
TO-92
170°C/W (0.125” leads)
SO-8
165°C/W
SOT-89
160°C/W
ϕ
JA
(junction to ambient)
Note 3:
Parameters identified with
boldface type
apply at temperature extremes. All other numbers apply at T
A
= T
J
= 25°C.
Note 4:
Guaranteed and 100% production tested.
Note 5:
Guaranteed but not 100% production tested. These limits are not used to calculate average outgoing quality levels.
Note 6:
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 0°C, 25°C, 70°C, 85°C.
PIN CONNECTIONS
TO-92
Plastic Package (N)
8L SOIC
SO Package (S)
+
8
N/C N/C N/C
7
6
5
SOT-89
(L)
3
2
1
3
1
2
3
N/C N/C N/C
4
-
N/C
2
+
1
-
Bottom View
Top View
Top View
TYPICAL APPLICATIONS
Wide Input
Range Reference
Micropower Reference
from 9V Battery
Reference from
1.5V Battery
V
IN
= 2.3V TO 30V
9V
1.5V
500k
LM334
1.2V
4.3k
AMS385-1.2
OUT
1.24V
AMS385-1.2
3k
1.2V
AMS385-1.2
Advanced Monolithic Systems, Inc.
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS285-1.2/AMS385-1.2
TYPICAL APPLICATIONS
(Continued)
0°C - 100°C Thermometer
°
°
Lower Power Thermometer
0°C - 100°C Thermometer
°
°
*
150
M
1.3 TO
1.6V‡
150
0-100µA M
I
OUT
R1
4k
R2
1k
R
AMS385-1.2
R3
100
R4
220
LM334
AMS385-1.2
8k TO
12k†
0-50µA
I
OUT
M
R1
2k
R2
1k
R
AMS385-1.2
R3
50
R4
100
V
+
LM334
V
-
1.5V
(1.3-1.6V)†
V
+
LM334
V
-
1.3-1.6V
* 2N3638 or 2N2907 select for inverse H
FE
≅
5
†
Select for operation at 1.3V
‡
I
Q
≅
600µA to 900
µA
Calibration
1. Short AMS385-1.2, adjust R3 for I
OUT
= temp at
1µA/°K
2. Remove short, adjust R2 for correct reading in
°C
†
I
Q
at 1.3V
≅
500
µA
I
Q
at 1.6V
≅
2.4mA
Calibration
1. Short AMS385-1.2, adjust R3 for I
OUT
= temp at
1.8µA/°K
2. Remove short, adjust R2 for correct reading in
°F
Centigrade Thermometer
Micropower* 10V Reference
I
Q
V
IN
= 15V
2.2k
V
+
LM334
V
-
1.5V†
R
2.3k
V1
V2
90k
25k
1M
2
+
7
LM4250C
3
1.2k
27k
AMS385-1.2
8
-
4
22M
150pF
3.5M
6
10V
OUTPUT
1mV/° C
R1
1k
AMS385-1.2
500k
Calibration
1. Adjust R1 so that V1 = temp at 1mV/°K.
2. Adjust V2 to 273.2mV.
†
I
Q
for 1.3V to 1.6V battery voltage = 50µA to 150µA
*I
Q
≅
20µA standby current
Advanced Monolithic Systems, Inc.
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS285-1.2/AMS385-1.2
TYPICAL APPLICATIONS
(Continued)
Micropower Thermocouple Cold Junction Compensator
V
+
LM334
2k
1%
5.1k
1M
1%
V
-
R
Adjustment Procedure
TC ADJ
500
MERCURY
+
CELL
1.345V
AMS385-1.2
ZERO ADJ
100k
1. Adjust TC ADJ pot until voltage across R1 equals Kelvin temperature
multiplied by the thermocouple Seebeck coefficient.
2. Adjust ZERO ADJ pot until voltage across R2 equals the thermocouple
Seebeck coefficient multiplied by 273.2.
Thermocouple
Type
Seebeck
Coefficient
(mV/
°
C)
52.3
42.8
40.8
6.4
R1
(Ω )
Ω
R2
Voltage
Voltage
(Ω ) Across R1
Ω
Across R2
@
25°C (mV)
°
(mV)
1.24k
1k
953Ω
150Ω
15.60
12.77
12.17
1.908
14.32
11.78
11.17
1.766
R2
R1
+
THERMOCOUPLE
+
-
-
COLD JUNCTION
ISO THERMAL
WITH LM334
METER
J
T
K
S
523
432
408
63.4
Typical supply current 50µA
Precision 1µ A to 1mA Current Sources
µ
AMS385-1.2
AMS385-1.2
30V
C1
150pF
R1
100k
2
-
LM312
3
I
OUT
*
-1.5V TO -27V
-30V
+
4
I
OUT
*
R2
1.5V TO 27V
R2
C1
150pF
2
-
LM312
6
3
+
4
7
6
R1
100k
7
*I
OUT
=1.23V/R2
Advanced Monolithic Systems, Inc.
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
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