Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
Advanced AMS9491
Monolithic 1.235V VOLTAGE REFERENCE
Systems
FEATURES APPLICATIONS
±10 mV max. initial tolerance (A grade) Battery Powered Systems
Operating Current 10µµA to 20mA Instrumentation
Low Voltage Reference 1.235 A/D, D/A Converters
Max. 0.6 Dynamic Impedance (A grade) Temperature measurement
Low Temperature Coefficient Current sources
Pagers
GENERAL DESCRIPTION
The AMS9491 is a two-terminal micropower band-gap voltage reference diode. It 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 AMS9491 is a band-gap reference, uses only transistors and resistors, low noise and good long-
term stability result. Careful design of the AMS9491 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 AMS9491 makes this reference diode useful for
micropower circuitry.
The AMS9491 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 AMS9491 is operating over a 0°C to 70°C temperature range and is available in TO-92 and SO-8 packages.
ORDERING INFORMATION:
TOL. PACKAGE TYPE OPERATING
TO-92 8 LEAD SOIC TEMPERATURE RANGE
±10mV AMS9491AN AMS9491AS 0 to 70° C
±20mV AMS9491BN AMS9491BS 0 to 70° C
PIN CONNECTIONS
TO-92 8L SOIC
Plastic Package (N) SO Package (S)
13
1 2
8
43
7 56
N/C N/CN/C
N/C N/C N/C
+
-
Bottom View Top View
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS9491
ABSOLUTE MAXIMUM RATINGS (Note 1)
Reverse Current 30mA Soldering information
Forward Current 10mA TO-92 package: 10 sec. 300°C
Operating Temperature Range 0°C to 70°C SOIC package: Vapor phase (60 sec) 215°C
Storage temperature -55°C to +150°C Infrared (15 sec.) 220°C
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at IR = 100 µA, and TA = +25°C unless otherwise specified.
Parameter Conditions AMS9491A AMS9491B Units
Min Typ Max Min Typ Max
Reverse Breakdown Voltage
(Note 4) IR - 100 µA1.215 1.235 1.255 1.215 1.235 1.255 V
Reverse Dynamic Impedance
(Note 4) IR - 100 µA, f =20Hz 0.2 0.6 0.2 0.6
Reverse Breakdown Voltage
Change with current (Note 4) 10µA IR 1mA
1mA IR 20mA 2.0
20 2.0
20 mV
Min. Operating Current (Note 4) 8 10
20 8 10
20 µA
Wide Band Noise
(Note 5)
IR - 100 µA,
10Hz f 10kHz 60 60 µV
Temperature Coeff.
(Note 6) 50 100 ppm/°C
Long Term Stability
(Note 5) TA=25°C±.1°C
T = 1000 Hr 20 20 ppm
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: Thermal resistance is as follows:
Thermal Resistance TO-92 SO-8
ϕ JA (junction to ambient) 170°C/W (0.125” leads) 165°C/W
Note 3: Parameters identified with boldface type apply at temperature extremes. All other numbers apply at TA = TJ = 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 TMAX and
TMIN, divided by TMAX - TMIN. The measured temperatures are 0°C, 25°C, 70°C.
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS9491
TYPICAL APPLICATIONS
Wide Input Micropower Reference Reference from
Range Reference from 9V Battery 1.5V Battery
4.3k
LM334
OUT
1.24V
AMS9491
V
IN
= 2.3V TO 30V
AMS9491
1.2V
500k
9V
AMS9491
1.2V
3k
1.5V
0°°C - 100°°C Thermometer Lower Power Thermometer 0°°C - 100°°C Thermometer
AMS9491
150
R1
4k
R2
1k
R3
100
R4
220
1.5V
(1.3-1.6V)†
R
V-
V+
LM334
M
0-100µA
IOUT
Calibration
1. Short AMS9491, adjust R3 for I
OUT
= temp at
1µA/°K
2. Remove short, adjust R2 for correct reading in °C
IQ at 1.3V 500 µA
IQ at 1.6V 2.4mA
LM334
M
AMS9491
1.3 TO
1.6V‡
*
8k TO
12k†
* 2N3638 or 2N2907 select for inverse HFE 5
Select for operation at 1.3V
IQ 600µA to 900 µA
AMS9491
150
R1
2k
R2
1k
R3
50
R4
100
1.3-1.6V
R
V-
V+
LM334
M
0-50µA
IOUT
Calibration
1. Short AMS9491, adjust R3 for I
OUT
= temp at
1.8µA/°K
2. Remove short, adjust R2 for correct reading in °F
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS9491
TYPICAL APPLICATIONS (Continued)
Centigrade Thermometer Micropower* 10V Reference
AMS9491
V+
V-
R
R1
1k
V1 V2
LM334 90k 25k
27k
1.2k
2.3k
OUTPUT
1mV/° C
2.2k
1.5V†
Calibration
1. Adjust R1 so that V1 = temp at 1mV/°K.
2. Adjust V2 to 273.2mV.
IQ for 1.3V to 1.6V battery voltage = 50µA to 150µA
150pF
AMS9491
3.5M
500k
22M
1M
7
4
6
3
2
-
+
VIN = 15V
IQ
10VLM4250C 8
*IQ 20µA standby current
Micropower Thermocouple Cold Junction Compensator
+
LM334
AMS9491
R1
R2
ZERO ADJ
100k
1M
1%
5.1k 2k
1%
TC ADJ
500
METER
MERCURY
CELL
1.345V
+
-
V+
V-
R
THERMOCOUPLE +
-
COLD JUNCTION
ISO THERMAL
WITH LM334
Adjustment Procedure
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 Seebeck R1 R2 Voltage Voltage
Type Coefficient () () Across R1 Across R2
(mV/ °°C) @ 25°°C (mV) (mV)
J 52.3 523 1.24k 15.60 14.32
T 42.8 432 1k 12.77 11.78
K 40.8 408 953 12.17 11.17
S 6.4 63.4 150 1.908 1.766
Typical supply current 50µA
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS9491
TYPICAL APPLICATIONS (Continued)
Precision 1µµA to 1mA Current Sources
7
4
3
2
+
-
LM312 6
AMS9491
R2
R1
100k
-30V
-1.5V TO -27V
C1
150pF
IOUT*
*IOUT =1.23V/R2
7
4
3
2
+
-
LM312 6
R2
R1
100k
30V
1.5V TO 27V
C1
150pF
IOUT*
AMS9491
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS9491
TYPICAL PERFORMANCE CHARACTERISTICS
-2
2
4
8
10
0.1 1 10 100
Reverse Characteristics
0
6
OUTPUT VOLTAGE CHANGE (mV)
T
A
=25° C
0.1
100
0.1 1 10 100
Reverse Dynamic Impedance
1
10
DYNAMIC IMPEDANCE ()
0.01 0
0.4
1.2
0.1 1 10 100
0.8
0.01
REVERSE CURRENT (mA)
REVERSE CURRENT (mA)
00.2 0.4 0.6 0.8 1.0 1.2
0.1
100
10
1.4
REVERSE VOLTAGE (V)
REVERSE CURRENT (µA)
1
Reverse Characteristics Forward Characteristics
FORWARD CURRENT (mA)
FORWARD VOLTAGE (V)
10 100 1k 10k 100k
0.1
1k
10
Reverse Dynamic Impedance
1M
FREQUENCY (Hz)
DYNAMIC IMPEDANCE ()
1
10k
100
-55 525 45 65 85 105
1.260
1.240
125
REFERENCE VOLTAGE (V)
Temperature Drift of 3
Representative Units
0
10
0
1.0
2.0
0200 400 600
TIME (µs)
Response Time
VOLTAGE SWING (V)
0.5
1.5
~
~
~
~
0
200
400
600
700
100 1k 10k 100k
Noise Voltage
100
500
NOISE (nV/Hz)
I
R
= 100
µ
A
10 FREQUENCY (Hz)
300
100 1k 10k 100k
CUTOFF FREQUENCY (Hz)
INTEGRATED NOISE (µV)
0
10
20
30
40
50
60
70
TEMPERATURE (° C)
1.250
1.230
1.220
-35 -15
I
R
= 100
µ
A
T
A
=-55° C
T
A
=125° C
T
A
=125° C T
A
=-55° C
T
A
=25° C
T
A
=-55° C
T
A
=25° C T
A
=125° C
T
A
=25° C
I
R
= 100
µ
A
T
A
=-55° C
T
A
=25° C
T
A
=125° C
I
R
= 100
µ
A
100
µ
AOUTPUT
AMS9491
OUTPUT
100k
INPUT
OUTPUT
INPUT
SINGLE POLE LOW PASS
SHARP CUTOFF
FILTER
Filtered Output Noise
0.01
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS9491
PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted.
3 LEAD TO-92 PLASTIC PACKAGE (N)
8 LEAD SOIC PLASTIC PACKAGE (S)
0.140±0.010
(3.556±0.127)
0.060±0.010
(1.524±0.254)
0.015±0.002
(0.381±0.051)
0.016±0.003
(0.406±0.076)
0.050±0.005
(1.270±0.127)
0.060±0.005
(1.524±0.127)
DIA
0.180±0.005
(4.572±0.127)
0.180±0.005
(4.572±0.127)
0.050
(1.270)
MAX
0.500
(12.70)
MIN UNCONTROLLED
LEAD DIMENSIONS
10°
NOM
5° NOM
N (TO-92 ) AMS DRW# 042391
0.90
(2.286)
NOM
0°-8° TYP
0.010-0.020
(0.254-0.508)
S (SO-8 ) AMS DRW# 042293
x 45°
0.016-0.050
(0.406-1.270)
0.008-0.010
(0.203-0.254)
0.004-0.010
(0.101-0.254)
0.014-0.019
(0.355-0.483)
0.053-0.069
(1.346-1.752)
0.050
(1.270)
TYP
0.150-0.157**
(3.810-3.988)
0.228-0.244
(5.791-6.197)
0.189-0.197*
(4.801-5.004)
*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
1 2 3 4
8 7 6 5