AS2931
100mA Low Dropout Voltage Regulator
FEATURES
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5.0V, 4.5V, 4.0V, 3.5V, 3.3V, and 3.0V Versions are Available
Output Current in Excess of 100 mA
Input-Output Differential is Less Than 0.6V
Mirror-Image Insertion Protection
Internal Thermal Overload Protection
Available in TO-220, TO-92, SOT-89, and SO-8 Package Types
Available as Adjustable with TTL Compatible Switch
Similar Improved to Industry Standard LM2931
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Reverse Battery Protection
Short Circuit Protection
60V Load Dump Protection
-20V Reverse Transient Protection
Portable Instrumentation
Radio Control Systems
Cordless Telephones
APPLICATION
PRODUCT DESCRIPTION
The AS2931 is a low power voltage regulator. This device is an excellent choice for use in battery-powered applications such as
cordless telephones, radio control systems, and portable computers. The AS2931 features offers very low quiescent currents
(0.4 mA.), and very low drop output voltage (typ. 50 mV at light load and 300 mV at 100 mA). Other features include the logic-
compatible On/Off input which enables the regulator to be switched on and off. The AS2931 is offered in a 3-pin TO-92/TO-220
package compatible with other 5V regulators and SOT-89/SO-8 package.
The regulator output voltage may be internally pin-strapped for a 3.5V, 3.3V, 3.0V, or programmed from 3V to 24V with an external
pair of resistors.
ORDERING INFORMATION
TO-92
3-PIN
AS2931AN-X
AS2931N-X
SO-8
AS2931AS-X
AS2931S-X
AS2931CS-X
SOT-89
3-PIN
AS2931AM1-X
AS2931M1-X
TO-220
3/5 PIN
AS2931AU-X
AS2931U-X
AS2931CU-X
OPER. TEMP.
RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN CONNECTIONS
8-Pin Surface Mount (S)
Fixed Output
V
OUT
GND
GND
BYP
1
2
8
7
V
IN
GND
GND
ON/OFF
X = Output Voltages (X = 3.0V, 3.3V, 3.5V)
or blank for Adj.)
TO-220-3 (U)
Fixed
TO-92 (N)
1
2
3
AS2931
1
2
3
V
OUT
AS2931
3
4
6
5
SOT-89 (M1)
Top View
8-Pin Surface Mount (S)
Adj Output
V
OUT
GND
1
2
8
7
V
IN
GND
GND
ON/OFF
AS2931
1
2
3
1. V
IN
2. GND
3. V
OUT
V
OUT
GND
V
IN
V
IN
GND
Bottom View
Top View
AS2931
GND
ADJ
3
4
6
5
Front View
Top View
Rev. 10/11/00
AS2931
ABSOLUTE MAXIMUM RATINGS
Power Dissipation........................................... Internally limited
Lead Temp. (soldering, 5 Seconds) ................................. 260°C
Storage Temperature Range ........................... -65°C to +150°C
Operating Junction Temperature Range ........... -40°C to +85°C
Input Supply Voltage............................................. -0.3 to +26V
ESD Rating.........................................................................2KV
ELECTRICAL CHARACTERISTICS
at V
S
= 14V, T
A
= 25°C, I
O
= 10 mA, C2 = 100
µF,
unless otherwise specified.
( Note 1)
Parameter
3.0 Volt Version
Output Voltage
6V<V
IN
< 26V,
I
O
= 100 mA Over Temp.
3.3 Volt Version
Output Voltage
6V < V
IN
< 26V,
I
O
= 100 mA Over Temp.
5 Volt Version
Output Voltage
6V <V
IN
< 26V,
I
O
=100 mA Over Temp.
All Voltage Options
Long Term Stability
Line Regulation
Load Regulation
Dropout Voltage
9V < V
IN
< 16V
6V < V
IN
< 26V,
5 mA < I
O
< 100 mA
I
O
=10 mA
I
O
=50 mA
I
O
=100 mA
I
O
< 10 mA, 6V < V
IN
< 26V
-40°C < Tj < 85°C
I
O
= 100 mA, V
IN
= 14V,
T
J
= 25°C
26
R
L
= 500Ω, V
O
<5.5V, 100ms
V
O
> -0.3V, R
L
= 500Ω
1% Duty Cycle,
τ
< 100ms,
R
L
= 500Ω
10Hz-100kHz, C
OUT
=100µF
F
O
= 120Hz
60
-15
-50
20
2.0
4.0
14
0.05
0.07
0.3
0.4
15
33
70
-30
-80
500
80
26
50
-15
-50
10
30
50
0.2
0.1
0.6
1.0
20
4.0
14
0.05
0.07
0.3
0.4
15
33
70
30
-80
500
80
30
50
0.2
0.1
0.6
1.0
mV/1000
mV
mV
V
V
V
mA
mA
V
V
V
V
µVrms
dB
4.81
4.75
2.94
Conditions
AS2931A
Min
Typ
Max
AS2931A-3
3.00
3.06
2.91
2.85
3.20
3.16
4.75
4.5
Min
AS2931
Typ
AS2931-3
3.00
3.09
V
V
V
V
V
V
Units
Max
3.00
3.12
2.88
AS2931A-3.3
3.23
3.20
3.30
3.36
3.00
3.15
AS2931-3.3
3.30
3.30
AS2931-5
5.00
3.39
3.43
5.25
5.5
3.30
3.39
AS2931A-5
5.00
5.19
5.25
Quiescent Current
Maximum Operational Input
Voltage
Maximum Line Transient
Reverse Polarity Input
Voltage, DC
Reverse Polarity Input
Voltage, Transient
Output Noise Voltage
Ripple Rejection
Note 1:
See
TYPICAL APPLICATIONS
notes to ensure constant junction temperature, low duty cycle pulse testing used.
Note 2:
All limits are at 25°C or over the full operating temperature junction range of -40°C to +85°C.
Note 3:
The maximum power dissipation is a function of maximum junction temperature, total thermal resistance, and ambient temperature.
Note 4:
Human body model, 100
µF
discharged through 1.5 KΩ.
Rev. 10/11/00
AS2931
Application Hints
The AS2931 requires an output capacitor for device stability.
The value required varies greatly depending upon the
application circuit and other factors. The high frequency
characteristics of electrolytic capacitors depend greatly on the
type and also on the manufacturer. Sometimes only bench
testing is the only means to determine the proper capacitor
type and value.
The high quality 100
µF
aluminum
electrolytic covers all general application circuits, this stability
can be obtained with a tantalum electrolytic value of 47
µF.
Another critical point of electrolytic characteristics is its
performance over temperature. The AS2931 is designed to
operate starting at -40°C which may not be true in the case of
electrolytic. Higher temperatures generally no problem. The
electrolytic. type in aluminum will freeze around -30°C. This
could cause an oscillation at output of regulator. At a lower
temperature requirement by many applications the capacitor
should maintain its performance. So as a result, for an
application which regulator junction temperature does not
exceed 25°C, the output capacitor can be reduced by the
factor of two over the value needed for the entire
temperature range.
Other points with linear regulators is that the twitch higher
output current stability decreases. In most applications the
AS2931 is operating at few milliamps. In these applications
the output capacitance can be further reduced. For example,
when the regulator is running at 10mA output current the
output capacitance value is half compared to the same
regulator that is running at 100 mA.
With the AS2931 adjustable regulator, the minimum value
of output capacitance is a function of the output voltage.
The value decreases with higher output voltages, since the
internal loop gain is reduced.
The worst case occurs at the lower temperature and
maximum operating currents, the entire circuit and the
electrolytic, should be cooled down to the minimum
temperature. The minimum of 0.6 volts required at the input
of regulator above the output to keep the power dissipation
and die heating to its minimum. After the value for the
capacitor has been determined for actual use, the value
should be doubled.
Rev. 10/11/00
AS2931
TYPICAL CHARACTERISTICS
QUIESCENT CURRENT
QUIESCENT CURRENT
REFERENCE VOLTAGE
25
QUIESCENT CURRENT (mA)
QUIESCENT CURRENT (mA)
30
25
20
15
10
5
0
-40
0
40
80
120
0
V
IN
= 14V
REFERENCE VOLTAGE (V)
1.30
1.28
1.26
1.24
1.22
1.20
1.18
1.16
1.14
1.12
1.10
LM2931CT ADJUSTABLE
20
15
10
3
2
1
0
JUNCTION TEMPERATURE (ºC)
I
O
= 0mA
~
~
I
O
= 50mA
~
~
30
60
90
0
3
6
9
12
15
18
21
24
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
PEAK OUTPUT CURRENT
DROPOUT VOLTAGE
INPUT OUTPUT DIFFERENTIAL (V)
INPUT OUTPUT DIFFERENTIAL (V)
DROPOUT VOLTAGE
0.6
0.5
0.4
0.3
0.2
0.1
0
0
40
80
120
JUNCTION TEMPERATURE (ºC)
LOW VOLTAGE BEHAVIOR
I
O
= 50mA
I
O
= 10mA
I
O
= 100mA
0.6
OUTPUT CURRENT (mA)
800
500
400
300
200
100
0
0
50
OUTPUT CURRENT (mA)
MAXIMUM POWER DISSIPATION (TO-220)
0.5
0.4
0.3
0.2
0.1
0
100
T
J
= 25ºC
T
J
= 85ºC
T
J
= -40ºC
0
10
20
30
INPUT VOLTAGE (V)
MAXIMUM POWER DISSIPATION (TO-92)
6.0
5.0
4.0
POWER DISSIPATION (W)
OUTPUT VOLTAGE (V)
18
16
14
12
10
8
6
4
2
0
NO HEAT SINK
10 ºC/W HEAT SINK
POWER DISSIPATION (W)
LM2931 5.0
I
O
= 100 mA
22
20
INFINITE HEAT SINK
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.125" LEAD LENGTH
FROM PC BOARD
3.0
2.0
0.4" LENGTH
FROMPC BOARD
1.0
2.0
3.0
4.0
5.0
6.0
0 10 20 30 40 50 60 70 80 90 100
AMBIENT TEMPERATURE (ºC)
0
10 20 30 40
50 60 70
80
90
INPUT VOLTAGE (V)
AMBIENT TEMPERATURE (ºC)
1.0
0.9
POWER DISSIPATION (W)
MAXIMUM POWER DISSIPATION (SO-
8)
MAXIMUM POWER DISSIPATION
OPERATION DURING LOAD DUMP
10
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
5
10
15
20
25
30
AMBIENT TEMPERATURE (ºC)
OUTPUT IMPEDANCE (
Ω)
0.8
1
OUTPUT
VOLTAGE (V)
LM2931-
5.0
I
O
= 10mA
70
60
50
40
30
20
10
0
~
~
6
4
2
0
-2
-100
0.1
0.01
0
30
60
90
120
150
FREQUENCY (Hz)
OUTPUT
VOLTAGE (V)
C
O
= 100µF
R
L
= 500W
~
~
0
100
200
300
400
500
TIME (ms)
Rev. 10/11/00
AS2931
TYPICAL APPLICATIONS
AS2931 Fixed Output
AS2931
SCHEMATIC DIAGRAM
Rev. 10/11/00
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