Advanced Monolithic Systems AMS421 Service Manual
Advanced AMS421
http://www.BDTIC.com/AMS
Monolithic 0.5V SHUNT REGULATOR
Systems
RoHS compliant
FEATURES APPLICATIONS
• Trimmed 0.5% Tolerance • Battery Powered Systems
• Wide Operating Current Range 0.1µA to 10mA • Switching Power Supplies
• Low Reference Input Current 1.5nA • Isolated Power Supplies
• Low Dynamic Output Impedance • Telecommunications
• Low Output Noise • Error Amplifiers
• Nominal Temperature Range to 125°C • Notebook/Personal Computer
• Temperature-Compensated: 50ppm/°C • Monitors/ VCR/ TV
• Low supply current: typ. 10µA • Opto-isolator driver
GENERAL DESCRIPTION
The AMS421 is a four-terminal adjustable open collector shunt regulator with guaranteed temperature stability over the entire
range of operation. The output voltage can be set to any value between 0.5V (V
The AMS421 features 0.5% initial tolerance, low dynamic output impedance and operates over a wide current range. Due to
the sharp turn-on characteristics this device is an excellent replacement for Zener diodes in many applications.
AMS421 is available 5 pin SOT-23 packages.
ORDERING INFORMATION: PIN CONNECTIONS
TOL. Package
5 LEAD SOT-23
±0.5%
±1.0%
±2.0%
AMS421AM1 -40 to + 125°C
AMS421BM1 -40 to + 125°C
AMS421CM1 -40 to + 125°C
OPERATING
TEMP. RANGE
BLOCK DIAGRAM
Ref
4
0.5V
V
CC
1
5
Co
+
-
2
GND
) and 15V by adding two external resistors.
REF
5L SOT-23
(M1)
1
VCC COLL
GND
2
N/C
3
Top View
5
4
REF
Advanced Monolithic Systems, Inc.
AMS421
http://www.BDTIC.com/AMS
ABSOLUTE MAXIMUM RATINGS (Note 1)
Supply Voltage (VCC) 15V Internal Power Dissipation (PD)
Continuous Collector Current (I
Reference Input Current (I
Junction Temperature (T
)
J
Storage temperature
Lead Temperature (Soldering, 10sec.)
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.
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at I
Parameter
Reference Voltage 497.5 500.0 502.25 495.0 500.0 505.0 490.0 500.0 510.0 mV
Conditions
) 10mA SOT-23-5 Package 0.3 W
C
) 0.5mA
REF
-40°C to +125°C
-65°C to +150°C
265°C
=1 mA and TA = +25°C unless otherwise noted.
COL
Thermal Resistance (θ
SOT-23-5 Package
AMS421A
Min Typ Max
Min Typ Max
AMS421B
)
JA
AMS421C
Min Typ Max
410°C/W
Units
Deviation of Reference
Voltage over
Temperature
Change in Reference
Voltage to Supply
Voltage
Reference Input
Current
Reference Input
Current Deviation over
Temperature
Off State Collector
Current
Dynamic Output
Impedance
Minimum Operating
Current
Input Supply Current I
= V
V
COL
T
= -40°C to
A
+125°C
I
COL
Vcc=1.4V to 15V
I
COL
10mA
I
COL
10mA
T
= Full Range
A
V
REF
f < 1KHz,
I
COL
V
COL
COL
REF
= 100µA
= 0.1µA to
= 0.1µA to
= 0V
=1 nA to 10mA
= V
REF
= 100 µA 15 20 15 20 15 20 µA
0.5 5 0..5 5 0.5 5
0.1 0.7 0.1 0.7 0.1 0.7
0.04 0.1 0.04 0.1 0.04 0.1 nA
0.35 0.5 0.35 0.5 0.35 0.5
0.1 0.1 0.1 nA
0.5
0.5
2.5
1.0 0.5 1.5 0.5 2 mV
0.5
3
RECOMMENDED OPERATING CONDITIONS:
Min Max
Collector Voltage, (V
Collector Current, (I
) V
COL
)
COL
15 V
REF
1µA
10mA
0.5
5
mV
nA
nA
Ω
Advanced Monolithic Systems, Inc.
http://www.BDTIC.com/AMS
AMS421
TYPICAL APPLICATIONS
Ref
4
LOW NOISE PRECISSION 1.000V REFERENCE
0.1µF
0.1µ
1.5V ≤ VCC ≤ 15V
+
-
0.5V
2.5V ≤ V
CC
1
2
≤ 15V
1
1.5V to 15V
10K
5
0.47µF
100K
100K
V
1.000V
500 pF
O
V
Q1
R
3
O
5
4
+
0.47µF
-
R
1
Co
0.5V
R
2
2
GND
Low cost LDO using an External PNP
Set the V
according to the following equation:
OUT
R1
⎞
⎛
1V V REFREFOUT +
+=
⎜
R2
⎝
R1I
⎟
⎠
Maximum output current is (PNP Hfe)10mA. The transistor current rating and package depends of the application dropout.
The power dissipation for the PNP transistor is Iout (Vin-Vout). The package type should be selected according to the Power
dissipation.
Advanced Monolithic Systems, Inc.
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