ETC AS2950CN-5.0

AS2950/AS2951
150mA Low Dropout Voltage Regulators
FEATURES
APPLICATIONS
• 5.0V, 3.3V, and 3.0V Versions at 150mA Output
• Very Low Quiescent Current
• Low Dropout Voltage
• Extremely Tight Load and Line Regulation
• Very Low Temperature Coefficient
• Needs Only 1µF for Stability
• Current & Thermal Limiting
• Unregulated DC Input can Withstand -20V Reverse Battery
and +60V Positive Transients
• Similar Replacement With Higher IOUT for LP2950/LP2951 Sockets
• Battery Powered Systems
• Cordless Telephones
• Radio Control Systems
• Portable/Palm Top/Notebook Computers
• Portable Consumer Equipment
• Portable Instrumentation
• Avionics
• Automotive Electronics
• SMPS Post-Regulator
• Voltage Reference
AS2951 Versions Only
• Error Flag Warns of Output Dropout
• Logic-Controlled Electronic Shutdown
• Output Programmable From 1.24V to 29V
PRODUCT DESCRIPTION
The AS2950 and AS2951 are low power voltage regulators. These devices are an excellent choice for use in battery-powered
applications such as cordless telephones, radio control systems, and portable computers. The AS2950 and AS2951 feature very low
quiescent current and very low dropout voltage (Typ. 50mV at light load and 380mV at 100mA). This include a tight initial tolerance
of 0.5% typ., extremely good load and line regulation of 0.05% typ. and very low output temperature coefficient, making the
AS2950/AS2951 useful as a low-power voltage reference. Other key additional features of this device includes higher output current
(150mA), positive transient protection up to 60V (Load dump), and the ability to survive an unregulated input voltage transient of 20V below ground (reverse battery).
The error flag output feature is used as power-on reset for warning of a low output voltage, due to falling voltage input of batteries.
Another feature is the logic-compatible shutdown input which enables the regulator to be switched ON and OFF. The AS2950 is
offered in a 3-Pin TO-92 package compatible with other 5V regulators. The AS2951 is also available in 8-Pin Plastic, SO-8 and
TO-99 metal can packages.
The regulator output voltage may be pin-strapped for a 5V, 3.3V and 3.0V or programmed from 1.24V to 29V with an external pair of
resistors. Look for AS2954 for 250mA and AS2955 for 350mA.
PIN CONNECTIONS
ORDERING INFORMATION
TO-92
3-PIN
SOIC
8-PIN
OPER. TEMP.
RANGE
AS2951ACS-X
AS2951CS-X
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
AS2950ACN-X
AS2950CN-X
X= Output Voltages (3.0V, 3.3V and 5.0V)
8-Pin Surface Mount
OUTPUT
1
SENSE
2
SHUTDOWN
GROUND
8
1
2
3
FEEDBACK
ALPHA 7
AS2951
3 AS2930
6
5V or 3.3V TAP
4
ERROR
5
TO-92 (N)
INPUT
VIN
V OUT
GND
Top View
Bottom View
Rev. 9/29/00
AS2950/AS2951
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
AS2951 .................................................. -55°C to +150°C
AS2950AC/AS2950C
AS2951AC/AS2951C............................ -40°C to +125°C
Input Supply Voltage (Survival) .........................-20 to +60V
Feedback Input Voltage .....................................-1.5 to +30V
Shutdown Input Voltage.....................................-0.3 to +30V
Error Comparator Output ...................................-0.3 to +30V
ESD Rating ............................................................. 2KV Min
ELECTRICAL CHARACTERISTICS at VS=15V, TA=25°C, unless otherwise specified.
Parameter
Conditions
Min
AS2951
Typ Max
AS2950C/AS2951C
Min Typ Max
AS2950C/AS2951C UNITS
Min Typ Max
2.985
2.970
2.964
2.958
3.0
3.0
3.0
3.0
3.015
3.030
3.036
3.042
2.970
2.955
2.940
2.928
3.0
3.0
3.0
3.0
3.030
3.045
3.060
3.072
V
3.284
3.267
3.260
3.254
3.3
3.3
3.3
3.3
3.317
3.333
3.340
3.346
3.267
3.251
3.234
3.221
3.3
3.3
3.3
3.3
3.333
3.350
3.366
3.379
V
4.975
4.95
4.94
4.93
5.0
5.0
5.0
5.0
5.025
5.050
5.06
5.07
4.95
4.925
4.90
4.88
5.0
5.0
5.0
5.0
5.05
5.075
5.10
5.12
V
3.0V Version
Output Voltage
TJ = 25°C
-25°C < TJ < 85°C
Full Operating Temperature
Output Voltage
100mA < IL < 150mA
TJ < TJMAX
2.985
3.0
3.015
2.964
2.955
3.0
3.036
3.045
3.284
3.3
3.317
3.260
3.251
3.3
3.340
3.350
4.975
5.0
5.025
5.0
5.06
5.075
20
120
20
0.03
0.04
50
380
450
0.1
0.1
80
450
500
0.03
0.04
50
380
450
0.1
0.1
80
450
500
0.04
0.1
50
380
450
0.2
0.2
80
450
500
150
3
5
170
6
8
150
3
5
170
6
8
150
3
5
170
6
8
µA
mA
mA
130
0.05
430
160
100
200
0.2
130
0.05
430
160
100
200
0.2
130
0.05
430
160
100
200
0.2
mA
%/W
V
3.3V Version
Output Voltage
TJ = 25°C
-25°C < TJ < 85°C
Full Operating Temperature
Output Voltage
100mA < IL < 150mA
TJ < TJMAX
V
5.0V Version
Output Voltage
TJ = 25°C
-25°C < TJ < 85°C
Full Operating Temperature
Output Voltage
100µA < IL < 150mA
TJ < TJMAX
4.94
4.925
V
All Voltage Options
Output Voltage Temperature
Coefficient
Line Regulation (Note 3)
Load Regulation (Note 3)
Dropout Voltage (Note 5)
Ground Current
Current Limit
Thermal Regulation
Output Noise,
10Hz to 100KHz
(Note 1)
6V < VIN < 30V (Note 4)
100mA < IL < 150mA
IL = 100µA
IL = 100mA
IL = 150mA
IL = 100µA
IL = 100mA
IL = 150mA
VOUT = 0
CL = 1µF
CL = 200µF
CL = 13.3µF
(bypass = 0.01µF pins 6 to 1
(AS2951))
8-Pin Version Only
Reference Voltage
Reference Voltage
AS2951
Over Temperature (Note 6)
1.22
1.19
1.235
50
AS2951AC
1.25
1.27
1.22
1.19
1.235
ppm/°
C
%
%
mV
µVrms
µVrms
µVrms
AS2951C
1.25
1.27
1.21
1.18
1.23
1.26
1.28
V
V
Rev. 9/29/00
AS2950/AS2951
PARAMETER
CONDITIONS
(Note 2)
AS2951
Min
Typ
Max
AS2950AC
AS2951AC
Min
Typ
Max
AS2950C
AS2951C
Min
Typ Max
40
20
40
20
40
50
UNITS
8-Pin Version only (Continued)
Feedback Pin Bias Current
Reference Voltage Temperature
Coefficient
Feedback Pin Bias Current
Temperature Coefficient
60
60
60
nA
ppm/°
C
nA/°C
1
µA
250
mV
60
75
15
95
mV
mV
mV
1.3
0.7
30
675
3
50
800
10
( Note 7 )
0.1
0.1
0.1
Error Comparator
Output Leakage Current
VOH = 30V
0.01
1
0.01
1
Output Low Voltage
VIN = 4.5V
IOL = 400µA
(Note 8)
(Note 8)
(Note 8)
150
250
150
250
Upper Threshold Voltage
Lower Threshold Voltage
Hysteresis
40
60
75
15
40
95
1.3
0.6
60
75
15
95
1.3
0.7
0.0
1
150
40
Shutdown Input
Input logic Voltage
Shut down Pin Input Current
Regulator Output Current in
Shutdown
Low (Regulator ON)
High (Regulator OFF)
VS = 2.4V
VS = 30V
(Note 9)
2
2
30
675
3
2
50
800
10
30
675
3
50
800
10
V
V
µA
µA
µA
Note 1: Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range.
Note 2: Unless otherwise specified all limits guaranteed for TJ = 25°C, VIN = 6V, IL = 100 µA and CL = 1 µF. Additional conditions for the 8-pin versions are
feedback tied to 5V Tap and output tied to output sense (VOUT = 5V) and VSHUTDOWN ≤ 0.8V.
Note 3: 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 4: Line regulation for the AS2951 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 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: VREF ≤VOUT ≤ (VIN - 1V), 2.3 ≤VIN≤30V, 100µA≤IL≤ 150 mA, TJ ≤ TJMAX.
Note 7: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 8: Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nominal reference voltage measured at 6V input. To
express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VOUT/VREF = (R1 + R2)/R2. For 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 VOUT as
VOUT is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.
Note 9: VSHUTDOWN ≥ 2V, VIN ≤ 30V, VOUT =0, Feedback pin tied to 5V Tap.
Note 10: All typical values are not guaranteed. The value could vary from lot to lot.
UNREGULATED DC
BLOCK DIAGRAM
7
+
INPUT
FEEDBACK
5V @ 150mA
MAX
1
8
OUTPUT
2
SENSE
+
_
FROM
CMOS OR
TTL
3
180k Ω ..
6
ERROR
AMPLIFIER
330k Ω ..
5V TAP
SHUTDOWN
60k Ω ..
+
60 mV
+
_
+ 1.23V
ERROR DETECTION
COMPARATOR
5
______
ERROR
+
1 µ F..
TO CMOS OR
TTL
4
REFERENCE
GROUND
AS2950 and A2951 Block Diagram
Rev. 9/29/00
AS2950/AS2951
APPLICATION HINTS
EXTERNAL CAPACITORS
The stability of the AS2950/AS2951 requires a 1.0µF or greater
capacitor between output and ground. Oscillation could occur
without this capacitor. Most types of tantalum or aluminum
electrolytic works fine here. For operations below -25°C solid
tantalum is recommended since many aluminum types have
electrolytes that freeze at about -30°C. The ESR of about 5Ω or
less and resonant frequency above 500kHz are the most
important parameters in the value of the capacitor. The capacitor
value can be increased without limit.
At lower values of output current, less output capacitance is
required for stability. For the currents below 10mA the value of
the capacitor can be reduced to 0.5µF and 0.15µF for 1mA. More
output capacitance is needed for the 8-pin version at voltages
below 5V since it runs the error amplifier at lower gain. At worst
case 5µF or greater must be used for the condition of 150mA
load at 1.23V output.
The AS2950, unlike other low dropout regulators will remain
stable in regulation with no load in addition to the internal
voltage divider.
This feature is especially important in
applications like CMOS RAM keep-alive. When setting the
output voltage of the AS2951 version with external resistors, a
minimum load of 1uA is recommended.
If there is more than 10 inches of wire between the input and the
AC filter capacitor or if a battery is used as the input then a 1µA
tantalum or aluminum electrolytic capacitor should be placed
from the input to the ground.
Instability can occur if there is stray capacitance to the AS2951
feedback terminal (pin 7). This could cause more problems when
using a higher value of external resistors to set the output voltage.
This problem can be fixed by adding a 100pF capacitor between
output and feedback and increasing the output capacitor to at
least 3.3µF.
ERROR DETECTION COMPARATOR OUTPUT
The Comparator produces a logic low output whenever the
AS2951 output falls out of regulation by more than around 5%.
This is around 60mV offset divided by the 1.235 reference
voltage. This trip level remains 5% below normal regardless of
the programmed output voltage of the regulator. Figure 1 shows
the timing diagram depicting the ERROR signal and the regulator
output voltage as the AS2951 input is ramped up and down. The
ERROR signal becomes low at around 1.3V input, and goes high
around 5V input (input voltage at which VOUT = 4.75 ). Since the
AS2951’s dropout voltage is load dependent, the input voltage
trip point (around 5V) will vary with the load current. The
output voltage trip point (approx. 4.75V) does not vary with load.
.
The error comparator has an open-collector output which requires an
external pull-up resistor. Depending on the system requirements the
resistor may be returned to 5V output or other supply voltage in
determining the value of this resistor, note that the output is rated to
sink 400µA, this value adds to battery drain in a low battery
condition. Suggested values range from 100K to 1MΩ. If the output
is unused this resistor is not required.
PROGRAMMING THE OUTPUT VOLTAGE OF AS2951
The AS2951 may be pin-strapped for 5V using its internal voltage
divider by tying Pin 1 (output) to Pin 2 (sense) and Pin 7 (feedback)
to Pin 6 (5V Tap). Also it may be programmed for any output voltage
between its 1.235V reference and its 30V maximum rating . As seen
in Figure 2, an external pair of resistors is required.
Refer to the below equation for the programming of the output
voltage.
VOUT = VREF × ( 1 + R1/R2 )+ IFBR1
The VREF is 1.235 and IFB is the feedback bias current, nominally
-20 nA. The minimum recommended load current of 1µA forces an
upper limit of 1.2 MΩ on value of R2. If no load presented the IFB
produces an error of typically 2% in VOUT which may be eliminated at
room temperature by trimming R1. To improve the accuracy choose
the value of R2 = 100k this reduces the error by 0.17% and increases
the resistor program current by 12µA. Since the AS2951 typically
draws 60µA at no load with Pin 2 open-circuited this is a small price
to pay.
REDUCING OUTPUT NOISE
It may be an advantage to reduce the AC noise present at the output.
One way is to reduce the regulator bandwidth by increasing the size of
the output capacitor. This is the only way that noise can be reduced
on the AS2950 but is relatively inefficient, as increasing the capacitor
from 1µF to 220 µF only decreases the noise from 430µV to
160µVRMS. for a 100kHz bandwidth at 5V output.
Noise could also be reduced fourfold by a bypass capacitor across R1,
since it reduces the high frequency gain from 4 to unity. Pick
CBYPASS ≅ 1 / 2πR1 × 200 Hz
or choose 0.01µF. When doing this, the output capacitor must be
increased to 3.3µF to maintain stability. These changes reduce the
output noise from 430µV to 100µVRMS. for a 100kHz bandwidth at
5V output. With the bypass capacitor added, noise no longer scales
with output voltage so that improvements are more dramatic at higher
output voltages.
Rev. 9/29/00
AS2950/2951
TYPICAL PERFORMANCE CHARACTERISTICS
QUIESCENT CURRENT
INPUT CURRENT
DROPOUT CHARACTERISTICS
10
250
6
RL=50k Ω
3
RL=50k Ω
2
RL = 50k Ω
175
150
125
100
RL =
75
50
1
1
0.1
25
0.01
0.1
0
0
0
1
2
3
4
5
0
6
1
2
OUTPUT VOLTAGE VS. TEMP OF 3
REPRESENTATIVE UNITS
5.06
10
3
150
GROUND CURRENT
0.2%
4.96
240
160
IL = 0
120
80
0
0
IL= 1mA
200
40
4.94
-75 -50 -25
INPUT CURRENT (mA)
GROUND CURRENT (µA)
4.98
25 50 75 100 125 150
0
1
2
3
4
5
6
7
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
8
1
2
3
5
4
6
7
8
9 10
INPUT VOLTAGE (VOLTS)
GROUND CURRENT
GROUND CURRENT
RL=50Ω
0
INPUT VOLTAGE (VOLTS)
TEMPERATURE (ºC)
QUIESCENT CURRENT
240
16
16
150
INPUT CURRENT
280
5.0
10
LOAD CURRENT (mA)
320
5.04
5.02
1
INPUT VOLTAGE (VOLTS)
INPUT VOLTAGE (VOLTS)
OUTPUT VOLTAGE (V)
8
4
GROUND PIN CURRENT (mA)
200
INPUT CURRENT (µA)
OUTPUT VOLTAGE (VOLTS)
225
5
V IN = 6V
IL = 100mA
8
QUIESCENT CURRENT (µA)
12
GROUND CURRENT
GROUND CURRENT (mA)
14
12
IL=100mA
10
8
6
4
0
-75 -50 -25
0
0
25 50 75 100 125 150
1
TEMPERATURE (ºC)
2
3
4
5
6
7
-75 -50 -25
8
SHORT CIRCUIT CURRENT
100
50
IL = 100µA
0
SHORT CIRCUIT CURRENT (mA)
DROP-OUT VOLTAGE (mV)
DROP-OUT VOLTAGE (mV)
IL = 100mA
~
~
400
300
200
TJ = 25ºC
100
0
-75 -50 -25
0
25 50 75 100 125 150
TEMPERATURE (ºC)
25 50 75 100 125 150
170
500
500
0
TEMPERATURE (ºC)
DROP-OUT VOLTAGE
DROP-OUT VOLTAGE
300
200
INPUT VOLTAGE
600
400
VIN =6V
IL =100mA
180
2
4
220
100µA
1mA
10mA
OUTPUT CURRENT
100mA
160
150
140
130
120
110
110
-75 -50 -25
0
25 50 75 100 125 150
TEMPERATURE (ºC)
Rev. 9/29/00
AS2950/AS2951
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
AS2951
COMPARATOR SINK CURRENT
ERROR COMPARATOR OUTPUT
100
mV
VOUT = 5V
4
HYSTERESIS
2
0
TA = 125ºC
2.0
1.5
TA = 25ºC
1.0
TA = -55ºC
0.5
PULLUP RESISTOR TO
SEPARATE 5V SUPPLY
-2
0
1
2
3
0.0
4
0
CL = 1µF
IL = 1mA
VOUT = 5V
-50
mV ~
~
8V
4V
0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
5
200
RIPPLE REJECTION
OUTPUT IMPEDANCE
600
400
800
TIME(µs)
OUTPUT LOW VOLTAGE (V)
10
RIPPLE REJECTION
90
90
80
80
IO = 1mA
2
IO = 100mA
1
0.5
VOUT = 5V
CL = 1µF
0.2
0.1
0.05
70
IL = 0
60
50
40
IL = 100µA
CL = 1µF
VIN = 6V
30
0.02
RIPPLE REJECTION (dB)
IO = 100µA
5
RIPPLE REJECTION (dB)
0.01
10
100
1K
10K
100K
1M
102
103
104
10 5
FREQUENCY (Hz)
FREQUENCY (Hz)
AS2951
MINIMUM OPERATING VOLTAGE
AS2951
FEEDBACK BIAS CURRENT
-50 -25
0
25
50
0
-10
60
150
40
LOAD OUTPUT VOLTAGE
CURRENT CHANGE (mV)
200
100
50
0
-50
CL = 1µF
VOUT = 5V
~
~
100
mA
0
25 50
75 100 125 150
µA
2
3
TIME (ms)
TA = 25ºC
-200
TA = 55ºC
-2.0
20
0
-20
CL = 1µF
VOUT = 5V
-40
4
5
-1.5 -1.0
-0.5
0
0.5
1.0
ENABLE TRANSIENT
-60
~
~
100
µA
1
-150
FEEDBACK VOLTAGE (V)
100
0
TA =1 25ºC
-100
-250
µA
100
106
-50
LOAD TRANSIENT RESPONSE
LOAD TRANSIENT RESPONSE
80
105
PIN 7 DRIVEN BY EXTERNAL
SOURCE (REGULATOR RUN
OPEN LOOP)
0
TEMPEATURE (ºC)
250
10 4
103
AS2951
FEEDBACK PIN CURRENT
10
TEMPERATURE
-100
IL = 10mA
10 2
50
-30
-75 -50 -25
75 100 125 150
40
FREQUENCY (Hz)
-20
0.01
-75
50
101
FEEDBACK CURRENT (µA)
BIAS CURRENT (nA)
0.1
60
106
20
1
CL= 1µF
VIN = 6V
VOUT = 5V
IL = 10mA
20
101
10
70
30
VOUT = 5V
20
SHUTDOWN OUTPUT
PINOUT VOLTAGE (V) VOLTAGE (V)
OUTPUT IMPEDANCE (OHMS)
50
mV
6V
INPUT VOLTAGE (V)
MINIMUM OPERATING VOLTAGE (V)
INPUT OUTPUT VOLTAGE
VOLTAGE CHANGE
6
SINK CURRENT (mA)
COMPARATOR OUTPUT (V)
8
LOAD OUTPUT VOLTAGE
CURRENT CHANGE (mV)
LINE TRANSIENT RESPONSE
2.5
7
6
5
4
3
2
IL = 10mA
VIN = 8V
CL = 10µF V OUT = 5V
1
0
2
0
-2
0
4
8
12
TIME (ms)
16
20
-100
0 100 200 300 400 500 600 700
TIME
Rev. 9/29/00
AS2950/AS2951
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
AS2950 MAXIUM RATED OUTPUT
TO-92 PACKAGE
0.25" LEADS SOLDERED
TO PC BOARD
80
T JMAX = 125 ºC
60
40
TA=25 ºC
TA = 85 ºC
20
300
200
100
60
40
5
10
20
15
25
-75 -50 -25
30
0
25
50
0
75 100 125 150
1.6
4
POWER OUTPUT VOLTAGE
DISSIPATION (W) CHANGE (mV)
5
1.4
1.2
1.0
0.8
0
-2
~
~
1
15
20
25
30
OUTPUT NOISE
3.5
2
1.25W
IL = 100mA
3.0
CL = 1µF
2.5
CL = 220µF
2.0
1.5
CL = 3.3µF
1.0
0.5
0
75 100 125 150
10
INPUT VOLTAGE (V)
0.0
-1
0.6
0
10
TEMPERATURE (ºC)
20
30
40
102
50
TIME (µs)
103
104
105
FREQUENCY (Hz)
LINE REGULATION
RIPPLE REJECTION
80
30
IL = 50µA
25
20
70
IL = 100µA
15
RIPPLE REJECTION (dB)
OUTPUT VOLTAGE CHANGE (mV)
5
THERMAL RESPONSE
1.8
25 50
T A = 85ºC
TEMPERATURE (ºC)
SHUTDOWN THRESHOLD VOLTAGE
-75 -50 -25 0
TA = 50ºC
0
0
INPUT VOLTAGE (V)
SHUTDOWN THRESHOLD VOLTAGE (V)
80
20
0
0
8-PIN
MOLDED
DIP SOLDERED
TO PC BOARD
T JMAX = 125º C
VOUT = 5V
T A = 25ºC
100
VOLTAGE NOISE
SPECTRAL DENSITY (µV/Hz)
OUTPUT CURRENT (mA)
120
OUTPUT CURRENT (mA)
Ω)
PIN 2 TO PIN 4 RESISTANCE (kΩ)
120
100
AS2950 MAXIUM RATED OUTPUT
CURRENT
AS2951 DIVIDER RESISTANCE
400
T J = 150 ºC
10
5
IL = 1mA
0
~
~
10
5
0
T J = 125 ºC
IL = 100µA
60
IL = 100mA
50
40
30
CL = 1µF
VIN = 6V
VOUT = 5V
20
-5
10
-10
5
10
15
20
INPUT VOLTAGE (V)
25
30
101
102
103
104
105
106
FREQUENCY (Hz)
Rev. 9/29/00
AS2950/AS2951
TYPICAL APPLICATIONS
+VIN
4.75V
OUTPUT
VOLTAGE
100K
8
ERROR
5
OUTPUT
_______
ERROR*
+VIN
______
ERROR
VOUT
AS2951
SHUTDOWN
INPUT
3
+5.0V
3.3uF
.01uF
FB
GND
7
1.23V
+
+1.3V
+
R1
SD
4
INPUT
VOLTAGE
1.2 to 30V
1
R2
VREF
+
Figure 2. Adjustable Regulator
* See Application Info.
_______
Figure 1. ERROR Output Timing
+VIN
+VIN
470KΩ
..
8
5
470KΩ
..
______
ERROR
+VIN
VOUT
ERROR
SD
4
______
ERROR
FB
1uF
SHUTDOWN
3
Latch Off When Error Flag Occurs
*VOUT = VIN
SD
GND
4
R2
1
ALPHA
2951
INPUT
7
+VIN
VOUT
+
R1
GND
5
OUTPUT
ALPHA
2951
3
8
VOUT
1
FB
7
*MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 4mV TO 400mV.
DEPENDING ON LOAD CURRENT. CURRENT LIMIT IS TYPICALLY 160mA
Wide Input Vltage Range Current Limiter
Rev. 9/29/00
AS2950/AS2951
TYPICAL APPLICATIONS (Continued)
+
6V
SEALED
120KΩ
LEADACID
BATTERY
SOURCE
FB
FOR 5.5 V
400KΩ
1.5K Ω
..
..
8
1N457
+VIN
AS385
VOUT
ALPHA
2951 SENSE
..
3
1
MEMORY V+
2
+
1uF
SD
100KΩ
MAIN V-
..
GND
4
20KΩ
..
NI-CAD
BACKUP
BATTERY
Low Battery Disconnect
8
Ω
39kΩ
5
2
SENSE
+V IN
ERROR
-
3
C4
1
V OUT
RESET
2951
SD
+V OUT = 5V
+
µF
1µ
7
FB
+
Ω
39kΩ
1%
GND
TAP
4
6
Ω
100kΩ
C1
Ω
100kΩ
+
6V
LEADACID
BATTERY
1%
Ω
1kΩ
<5.8V**
C2
+
Ω
100kΩ
<6.0V**
1%
Ω
1kΩ
C3
Ω
100kΩ
+
<6.2V**
R3
1%
Ω
10kΩ
Ω
20kΩ
*OPTIONAL LATCH OFF WHEN DROPOUT OCCURS.
ADJUST R3 FOR C2 SWITCHING VIN IS 6.0V.
**OUTPUTS GO LOW WHEN VIN DROPS BELOW
DESIGNATED THRESHOLDS.
Regulator with State-of-Charge Indicator
Rev. 9/29/00
AS2950/AS2951
TYPICAL APPLICATIONS (continued)
+
6V
SEALED 120K
Ω ..
LEADACID
BATTERY
SOURCE FB
1.5K Ω ..
8
1N457
+V IN
AS385
V OUT
2951
400KΩ ..
FOR 5.5 V
1
MEMORY V+
SENSE
2
3
+
1uF
SD
100KΩ ..
MAIN V-
GND
4
20KΩ ..
NI-CAD
BACKUP
BATTERY
Low Battery Disconnect
8
39kΩ ..
2
SENSE
+VIN
5 ______
ERROR
V OUT
RESET
-
3
C4
+
2951
SD
FB
39kΩ ..
1%
GND
4
1
+VOUT = 5V
+
1uF
7
TAP
6
100kΩ ..
C1
100kΩ ..
+
6V
LEADACID
BATTERY
1%
1kΩ ..
<5.8V**
C2
+
100kΩ ..
<6.0V**
1%
1kΩ ..
C3
100kΩ ..
+
<6.2V**
R3
1%
10kΩ ..
20kΩ ..
*OPTIONAL LATCH OFF WHEN DROPOUT OCCURS. ADJUST R3
FOR C2 SWITCHING VIN IS 6.0V.
**OUTPUTS GO LOW WHEN VIN DROPS BELOW DESIGNATED
THRESHOLDS.
Regulator with State-of-Charge Indicator
Rev. 9/29/00
AS2950/AS2951
TYPICAL APPLICATIONS (continued)
+VIN
8
3
AUX SHUTDOW
INPUT
+VIN
SD
10K Ω ..
_______ 5
ERROR
5 DEGREE SHUTDOWN
FLAG
OFF
ON
2951
1
FB
GND
4
+
TEMP
SENSOR
V OUT
7
AS35
-
EXTERNAL CIRCUIT
PROTECTED
FROM
OVER
TEMPERATURE
(V+ GOES OFF
WHEN
TEMP > 125)
OR
RELAY
8.2K
Ω ..
System Over Temperature Protection Circuit
+5V
4
4.7mA
20mA
UNREGULATED INPUT
8
OUTPUT
+V IN
V OUT
5
1
IN
V OUT
1
1N4001
FB
7
2951
2
3
GND
4
2N5432
27KΩ ..
2951
0.1uF
330KΩ ..
360K Ω
1N457
..
V TAP
FB
7
SENSE
GND
5V
2
MIN VOLTAGE = 4V
Open Circuit Detector for 4mA to 20mA Current Loop
OUTPUT
+
4
4.7uF
LOAD
50mA
TO
300 mA
300 mA Regulator with 0.75 Dropout
Rev. 9/29/00
AS2950/AS2951
SCHEMATIC DIAGRAM
Rev. 9/29/00