•• Extremely Tight Load and Line Regulation•• Portable Instrumentation
•• Very Low Temperature Coefficient•• Radio Control Systems
•• Current and Thermal Limiting•• Automotive Electronics
•• Needs Minimum Capacitance (1µµF) for Stability•• Avionics
•• Unregulated DC Positive Transients 60V•• Low-Power Voltage Reference
ADDITIONAL FEATURES (AMS2951 ONLY)
•• 1.24V to 29V Programmable Output
•• Error Flag Warning of Voltage Output Dropout
•• Logic Controlled Electronic Shutdown
GENERAL DESCRIPTION
The AMS2950 and AMS2951 are micropower voltage regulators ideally suited for use in battery-powered systems. These
devices feature very low quiescent current (typ.75µA), and very low dropout voltage (typ.45mV at light loads and 380mV at
150mA) thus prolonging battery life. The quiescent current increases only slightly in dropout. The AMS2950/AMS2951 has
positive transient protection up to 60V and can survive unregulated input transient up to 20V below ground.
The AMS2950 and AMS2951 were designed to include a tight initial tolerance (typ. 0.5%), excellent load and line regulation
(typ. 0.05%), and a very low output voltage temperature coefficient, making these devices useful as a low-power voltage
reference.
The AMS2950 is offered in the 3-pin TO-92 package. AMS2951 is available in 8-pin plastic SOIC and DIP packages and
offers three major additional system features. An error flag output warns of a low output voltage, often due to failing batteries
on input. The AMS2951 also features the logic-compatible shutdown input which enables the regulator to be switched on and
off. The AMS2951 device may be pin-strapped for a 5.0V, 3.3V, 3.0V or 2.5 output, or programmed from 1.24V to 29V with
an external pair of resistors.
ORDERING INFORMATION PIN CONNECTION
X = 3.3V, 3.0V, 2.5V
OUTPUT
SENSE
SHUTDOWN
GROUND
OUTPUT
1
2
3
4
Top View
TO-92
8
INPUT
7
FEEDBACK
6 V
TAP
5
ERROR
INPUT
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
GND
Bottom View
AMS2950/AMS2951
Internally Limited
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage-0.3 to +30V Wave
SHUTDOWN Input Voltage, Infrared
Error Comparator Output Vapor Phase
Voltage,(Note 9)ESD TBD
FEEDBACK Input Voltage -1.5 to +30V
(Note 9) (Note 10)
OPERATING RATINGS (Note 1)
Power Dissipation
Junction Temperature
Storage Temperature
+150°C
-65°C to +150°C
Max. Input Supply Voltage30V
Junction Temperature Range
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the
device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the
Electrical Characteristics tables.
Note 2: Unless otherwise specified all limits guaranteed for V
IN
= ( V
+1)V, IL = 100 µA and CL = 1 µF for 5V versions and 2.2µF for 3V and 3.3V
ONOM
versions. Limits appearing in boldface type apply over the entire junction temperature range for operation. Limits appearing in normal type apply for TA = TJ =
25°C Additional conditions for the 8-pin versions are FEEDBACK tied to V
, OUTPUT tied to SENSE and V
TAP
SHUTDOWN
≤ 0.8V.
Note 3: Guaranteed and 100% production tested.
Note 4: Guaranteed but not 100% production tested. These limits are not used to calculate outgoing AQL levels.
Note 5: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V
differential. At very low values of programmed output voltage, the minimum input supply voltage of 2V ( 2.3V over temperature) must be taken into account.
Note 6: Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nominal reference voltage measured at
V
IN
= ( V
+1)V. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = Vout/Vref = (R1 + R2)/R2. For
ONOM
example, at a programmed output voltage of 5V, the error output is guaranteed to go low when the output drops by 95 mV x 5V/1.235 = 384 mV. Thresholds
remain constant as a percent of V
Note 7: V
is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.
out
out
JMAX
.
µA
V
V
µA
µA
µA
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS2950/AMS2951
Note 8: The junction-to-ambient thermal resistance are as follows:180°C/W and 160°C/W for the TO-92 (N) package with 0.40 inch and 0.25 inch leads to the
printed circuit board (PCB) respectively, 105°C/W for the molded plastic DIP (P) and 160°C/W for the molded plastic SO-8 (S). The above thermal resistances
for the N, S and P packages apply when the package is soldered directly to the PCB.
Note 9: May exceed input supply voltage.
Note 10: When used in dual-supply systems where the output terminal sees loads returned to a negative supply, the output voltage should be diode-clamped to
ground.
Note 11: V
Note 12: Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range.
Note 13: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line
regulation effects. Specifications are for a 50mA load pulse at VIN =30V (1.25W pulse) for T =10 ms.
Note 14: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects
are covered under the specification for thermal regulation.
Note 15: Line regulation for the AMS2951 is tested at 150°C for IL = 1 mA. For IL = 100 µA and TJ = 125°C, line regulation is guaranteed by design to 0.2%.
See typical performance characteristics for line regulation versus temperature and load current.
Note 16: All AMS2950 devices have the nominal output voltage coded as the last two digits of the part number. In the AMS2951 products, the 2.5V 3.0V and
3.3V versions are designated by the last two digits, but the 5V version is denoted with no code of the part number.
BLOCK DIAGRAM AND TYPICAL APPLICATIONS
UNREGULATED DC
+
≥ 2V, Vin ≤ 30V, V
shutdown
INPUT
+
-
+
1.23V
REFERENCE
=0, Feedback pin tied to 5V
out
TAP
.
AMS2950-XXAMS2951-XX
UNREGULATED DC
ERROR
AMPLIFIER
OUTPUT
GROUND
V
IL≤ 150mA
+
SEE APPLICATION
OUT
HINTS
FROM
CMOS
OR TTL
+
FEEDBACK
+
+
-
+
+
-
1.23V
REFERENCE
3
SHUT-
DOWN
50mV
ERROR DETECTION COMPARATOR
INPUTOUTPUT
ERROR
AMPLIFIER
187
SENSE
V
TAP
ERROR
GROUND
V
OUT
I
150mA
≤
L
2
SEE APPLICATION
330k
+
Ω
6
5
4
HINTS
TO CMOS
OR TTL
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
TYPICAL PERFORMANCE CHARACTERISTICS
AMS2950/AMS2951
Quiescent Current
10
1
0.1
GROUND CURRENT (mA)
0.01
0.1110150
LOAD CURRENT (mA)
Input Current
270
240
210
180
150
RL= 50Ω
120
90
75
60
45
INPUT CURRENT (mA)
30
15
0
12 3 4 5 6 7 8 9 100
INPUT VOLTAGE (V)
Dropout Characteristics
6
5V OUTPUT
5
4
RL= 50 kΩ
3
2
OUTPUT VOLTAGE (V)
1
0
12345612 3 4 5 67 8 9 100
0
INPUT VOLTAGE (V)
Temperature Drift of 3
Representative Units
5.06
5V OUTPUT5V OUTPUT5V OUTPUT
5.04
5.02
5.0
4.98
OUTPUT VOLTAGE (V)
4.96
4.94
-750 25 50 75 100 125
-50 -25
TEMPERATURE (° C)
RL= 50Ω
0.2%
150
Input Current
250
225
5V OUTPUT
200
175
150
125
100
RL= ∞
75
INPUT CURRENT (µA)
50
25
0
INPUT VOLTAGE (V)
Quiescent Current
160
140
120
100
80
60
40
20
QUIESCENT CURRENT (µA)
0
012345678
INPUT VOLTAGE (V)
RL= 50 kΩ
IL= 1 mA
IL= 0
Quiescent Current
120
110
100
90
80
70
60
QUIESCENT CURRENT (µA)
50
-75
5V OUTPUT
-50 -25
0 25 50 75 100 125
TEMPERATURE (° C)
IL= 100µA
VIN= 6V
QUIESCENT CURRENT (mA)
150
Quiescent Current
5V OUTPUT
9
8
7
-50 -25
-75
TEMPERATURE (° C)
VIN= 6V
IL= 150mA
0 25 50 75 10012510150
Quiescent Current
8
5V OUTPUT
7
6
5
4
3
2
1
QUIESCENT CURRENT (µA)
0
012345678
INPUT VOLTAGE (V)
IL= 150mA
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
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