LP2950AS-3.0 [SIPEX]
100 mA Low Dropout Voltage Regulators; 百毫安低压差稳压器
| 型号： | LP2950AS-3.0 |
| 厂家： | 
SIPEX CORPORATION |
| 描述： | 100 mA Low Dropout Voltage Regulators |
| 文件： | 总13页 (文件大小：441K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LP2950/LP2951
100mA Low Dropout Voltage Regulators
FEATURES
• 5.0V and 3.3V Versions at 100mA Output
• Very Low Quiescent Current
APPLICATIONS
• Battery Powered Systems
• Cordless Telephones
• Low Dropout Voltage: 380mV at 100mA
• Extremely Tight Load and Line Regulation
• Very Low Temperature Coefficient
• Current & Thermal Limiting
• Radio Control Systems
• Portable/Palm Top/Notebook Computers
• Portable Consumer Equipment
• Portable Instrumentation
• Avionics
• Need Only 1 µF for Stability
• Offered in TO-92 (LP2950) & SOIC (LP2951)
• Direct Replacement For LP2950/LP2951
• SMPS Post-Regulator
• Voltage Reference
• Automotive Electronics
LP2951 versions only
• Error Flag Warns of Output Dropout
• Logic-Controlled Electronic Shutdown
• Output Programmable From 1.24 to 29V
Now Available in Lead Free Packaging
PRODUCT DESCRIPTION
The LP2950 and LP2951 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 LP2950 and LP2951 feature low
quiescent current and low dropout voltage (typ. 50mV at light load and 380 mV at 100mA). This includes a tight initial tolerance
(0.5% typ.), extremely good load and line regulation (0.05% typ.), and very low output temperature coefficient (20 ppm/¡C typ.),
making the LP2950/LP2951 useful as a low-power voltage reference.
The error flag output feature is used as a power-on reset for warning of a low output voltage, due to a falling input voltage. The logic-
compatible shutdown feature enables the regulator to be switched ON and OFF. The LP2950 is offered in a 3-pin TO-92 package
compatible with other 5V, 3.3V regulators. The LP2951 is available in an 8-lead SOIC package.
Block diagram of LP2951
UNREGULATED DC
5V @ 100mA
MAX
1
7
8
+
INPUT
FEEDBACK
OUTPUT
2
SENSE
180k
Ω
+
_
6
ERROR
3
FROM
CMOS OR
TTL
AMPLIFIER
330k
Ω
5V TAP
SHUTDOWN
+
60 mV
60k
Ω
1µF
.
5
______
ERROR
+
+
_
.
ERROR DETECTION
COMPARATOR
TO CMOS OR
TTL
1.23V
+
4
REFERENCE
GROUND
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
1
LP2950/51
ABSOLUTE MAXIMUM RATINGS
Power Dissipation.....................................Internally Limited
Lead Temp. (Soldering, 5 Seconds)............................260¡C
Storage Temperature Range......................... -65¡ to +150¡C
Feedback Input Voltage................................................ -1.5V to +30V
Shutdown Input Voltage............................................... -0.3V to +30V
Error Comparator Output ............................................. -0.3V to +30V
ESD Rating .........................................................................2kV Min
Operating Junction Temperature Range
-40C to +125C
Input Supply Voltage..................................... -0.3V to +30V
ELECTRICAL CHARACTERISTICS VIN=6V, IO=100µA, COUT=1µF (Note 2) TA=25C, unless otherwise noted.
LP2950AC
LP2951AC
LP2950C
LP2951C
PARAMETER
CONDITIONS
Min.
Typ. Max.
Min.
Typ. Max.
UNITS
3.3 V Versions
T = 25¡C
Output Voltage
Output Voltage
3.284
3.267
3.260
3.3
3.3
3.3
3.317
3.333
3.340
3.267
3.251
3.234
3.3
3.3
3.3
3.333
3.350
3.366
V
J
-25¡C ≤T ≤85¡C
J
Full Operating Temperature
100 µA ≤IL ≤100 mA
3.254
3.3
3.346
3.221
3.3
3.379
V
T ≤TJMAX
J
5 V Versions
Output Voltage
TJ = 25¡C
4.975
4.950
4.940
5.0
5.0
5.0
5.025
5.050
5.060
4.950
4.925
4.900
5.0
5.0
5.0
5.050
5.075
5.100
V
V
-25¡C ≤TJ ≤85¡C
Full Operating Temperature
100 µA ≤IL ≤100 mA
TJ ≤TJMAX
Output Voltage
4.925
5.0
5.075
4.880
5.0
5.120
All Voltage Options
Output Voltage
20
120
50
150
ppm/¡C
Temperature Coefficient
(Note 1)
6V ≤V ≤30V (Note 4)
Line Regulation (Note 3)
0.03
0.04
0.1
0.1
0.04
0.1
0.2
0.2
%
%
IN
Load Regulation (Note 3)
100 µA ≤IL ≤ 100 mA
Dropout Voltage
(Note 5)
IL = 100 µA
IL = 100 mA
50
380
80
450
50
380
80
450
mV
mV
Ground Current
IL = 100 µA
IL = 100 mA
150
8
170
12
150
8
170
12
µA
mA
Current Limit
VOUT = 0
150
0.05
430
160
100
200
0.2
150
0.05
430
160
100
200
0.2
mA
Thermal Regulation
Output Noise,
%/W
CL = 1µF
µV rms
µV rms
µV rms
10Hz to 100KHz
CL = 200 µF
CL = 3.3 µF, Bypass = 0.01µF
from Pin 7 to Pin 1 (LP2951)
8-Pin Versions only
LP2951AC
LP2951C
Reference Voltage
1.220
1.190
1.235
1.250
1.270
60
1.210
1.185
1.235
1.260
1.285
60
V
V
Reference Voltage
Over Temperature (Note 6)
Feedback Pin Bias
Current
40
40
nA
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
2
LP2950/51
CONDITIONS
LP2951AC
Typ. Max.
LP2951C
Typ. Max.
PARAMETER
(Note 2)
Min.
Min.
UNITS
8-Pin Versions only (Continued)
Reference Voltage
Temperature
20
50
ppm/¡C
Coefficient
Feedback Pin Bias
Current
0.1
0.1
nA/¡C
Temperature Coefficient
Error Comparator
Output Leakage Current
Output Low Voltage
VOH = 30V
VIN = 4.5V
0.01
150
1
0.01
150
1
µA
250
250
mV
IOL = 400µA
Upper Threshold
Voltage
Lower Threshold
Voltage
(Note 7)
40
60
75
15
40
60
75
15
mV
mV
mV
(Note 7)
(Note 7)
95
95
Hysteresis
Shutdown Input
Input logic Voltage
Low (Regulator ON)
High (Regulator OFF)
VS = 2.4V
1.3
0.7
1.3
0.7
V
V
µA
µA
2.0
2.0
Shut down Pin Input
Current
30
675
50
800
30
675
50
800
VS= 30V
Regulator Output
(Note 8)
3
10
3
10
µA
Current in Shutdown
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 = 100µA and CL = 1µF. 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 LP2951 is tested at IL = 1mA. 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≤ 100mA, TJ ≤ TJMAX
.
Note 7: 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 8: VSHUTDOWN ≥ 2V, VIN ≤ 30V, VOUT =0, Feedback pin tied to 5V Tap.
Note 9: All typical values are not guaranteed. The value could vary from lot to lot.
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
3
LP2950/ LP2951
TYPICAL PERFORMANCE CHARACTERISTIC
10
6
250
225
200
5
4
RL = 50kΩ
175
150
1
RL
=
3
2
125
RL=50kΩ
RL
=
100
75
0.1
50
25
0
1
0
0.01
0
1
2
3
4
5
6
7
8
9
10
0.1
1
10
100
0
1
2
3
4
5
6
INPUT VOLTAGE (VOLTS)
LOAD CURRENT (mA)
INPUT VOLTAGE (VOLTS)
Input Current
Quiescent Current
Dropout Characteristics
16
320
280
160
150
140
130
120
110
100
90
Ω
RL=50
240
200
160
VOUT = 5V
12
IL= 1mA
IL= 0
VIN = 6V
IL = 100mA
80
70
120
80
60
50
40
30
20
10
0
8
4
40
0
0
1
2
3
4
5
6
7
8
-75
-25
0
25 50 75 100 125 150
-50
0
1
2
3
4
5
6
7
8
9 10
INPUT VOLTAGE (VOLTS)
TEMPERATURE (ºC)
INPUT VOLTAGE (VOLTS)
Ground Current
Ground Current
Input Current
16
190
170
150
130
14
12
IL=100mA
VIN =6V
IL =100uA
1
0
8
6
4
2
0
-75 -50 -25
0
25 50 75 100 125 150
0
1
2
3
4
5
6
7
8
TEMPERATURE (ºC)
INPUT VOLTAGE
Ground Current
Quiescent Current
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
4
LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
600
500
400
300
170
160
150
140
130
120
110
IL = 100mA
500
400
300
100
~
200
~
TJ = 25ºC
100
0
50
0
IL = 100µA
110
100µA
1mA
OUTPUT CURRENT
10mA
100mA
-75 -50 -25
0
25 50 75 100 125 150
-75 -50 -25
0
25 50 75 100 125 150
TEMPERATURE (ºC)
TEMPERATURE (ºC)
Drop-Out Voltage
Drop-Out Voltage
Short Circuit Current
8
6
4
2.5
2.0
100
mV
VOUT = 5V
TA = 125ºC
50
mV
0
1.5
1.0
TA = 25ºC
TA = -55ºC
CL = 1µF
IL = 1mA
VOUT = 5V
HYSTERESIS
-50
mV
~
2
0
~
8V
0.5
0.0
6V
4V
PULLUP RESISTOR TO
SEPARATE 5V SUPPLY
-2
0
1
2
3
4
5
0
200
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
400
600
800
INPUT VOLTAGE (V)
OUTPUT LOW VOLTAGE (V)
TIME(µs)
Error Comparator Output
LP2951 Comparator Sink Current
Line Transient Response
10
90
80
90
80
IO = 100µA
5
CL= 1µF
IO = 1mA
2
VIN = 6V
VOUT = 5V
70
70
60
50
40
30
20
IL = 1mA
IL = 0
IO = 100mA
1
60
50
40
0.5
0.2
VOUT = 5V
CL = 1µF
0.1
0.05
IL = 100µA
CL = 1µF
VIN = 6V
VOUT = 5V
30
20
0.02
0.01
IL = 10mA
10 4
103
10 2
10 5
106
10 1
10 2
10 3
FREQUENCY (Hz)
10 4
10 5
10 6
10
100
1K
FREQUENCY (Hz)
10K
100K
1M
10 1
FREQUENCY (Hz)
Output Impedance
Ripple Rejection
Ripple Rejection
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
5
LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
20
50
0
2.3
PIN 7 DRIVEN BY EXTERNAL
SOURCE (REGULATOR RUN
OPEN LOOP)
10
-50
2.1
0
TA=1 25ºC
-100
-150
-200
-250
-10
TA = 25ºC
TA = 55ºC
1.9
-20
-30
1.7
-75 -50 -25
-75 -50 -25
0
25 50 75 100 125 150
-2.0
-1.5 -1.0 -0.5
0
0.5
1.0
0
25 50 75 100 125 150
TEMPEATURE (ºC)
FEEDBACK VOLTAGE (V)
TEMPERATURE
LP2951 Minimum Operating Voltage
LP2951 Feedback Bias Current
LP2951 Feedback Pin Current
250
200
150
80
60
40
7
CL = 1µF
6
5
4
100
50
0
20
0
3
-20
2
1
0
IL = 10mA
VIN = 8V
CL = 10µF
VOUT = 5V
-50
-40
CL = 1µF
VOUT = 5V
-100
-60
CL = 10µF
V OUT = 5V
~
~
~
~
100
mA
2
0
100
µA
100
100
µA
µA
-2
0
1
2
3
4
5
-100
0
100 200 300 400 500 600 700
0
4
8
12
16
20
TIME (ms)
TIME (us)
TIME (ms)
Load Transient Response
Load Transient Response
Enable Transient
120
400
300
200
120
8-PIN
MOLDED
TO-92 PACKAGE
0.25" LEADS SOLDERED
TO PC BOARD
DIP SOLDERED
TO PC BOARD
TJMAX = 125º C
100
80
100
80
VOUT = 5V
Vout=5V
TJMAX = 125 ºC
60
60
TA = 25ºC
40
TA=25 ºC
40
20
0
TA = 50ºC
100
0
TA = 85 ºC
20
0
TA = 85ºC
0
5
10
15
20
25
30
-75 -50 -25
0
25 50 75 100 125 150
0
5
10
15
20
25
30
INPUT VOLTAGE (V)
TEMPERATURE (ºC)
INPUT VOLTAGE (V)
LP2950 Maxium Rated Output
LP2951 Divider Resistance
LP2950 Maxium Rated Output Current
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
6
LP2950/LP2951
TYPICAL APPLICATIONS
1.8
1.6
5
4
3.5
3.0
IL = 100mA
CL = 1µF
2.5
2.0
1.5
1.0
2
1.4
1.2
CL = 220µF
0
CL = 3.3µF
CBYP = 0.1µF
-2
1
~
~
1.0
0.8
0.6
1.25W
30
0.5
0.0
0
-1
0
10
20
40
50
10 2
10 3
10 4
=0.1uF
10 5
-75 -50 -25
0
25 50 75 100 125 150
TIME (µs)
TEMPERATURE (¼C)
FREQUENCY (Hz), CBYP
Shutdown Threshold Voltage
Thermal Response
Output Noise
80
70
60
50
40
30
20
10
30
25
20
15
IL = 50µA
IL = 100µA
TJ = 150 ¼C
IL = 100mA
10
5
IL = 1mA
0
~
~
CL = 1µF
VIN = 6V
VOUT = 5V
10
5
TJ = 125 ¼C
IL = 100µA
0
-5
-10
10 1
10 2
10 3
FREQUENCY (Hz)
10 4
10 5
10 6
5
10
15
20
25
30
INPUT VOLTAGE (V)
Line Regulation
Ripple Rejection
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
7
LP2950/51
remains 5% below normal regardless of the programmed output
voltage of the regulator.
APPLICATION HINTS
EXTERNAL CAPACITORS
The stability of the LP2950/LP2951 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 the 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 capacitors value may be increased without limit.
Figure 1 shows the timing diagram depicting the ERROR signal and
the regulator output voltage as the LP2951 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 LP2951Õs 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.
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 0.33µF and 0.1µF 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 3.3 µF or
greater must be used for the condition of 100mA load at 1.23V
output.
PROGRAMMING THE OUTPUT VOLTAGE OF LP2951
The LP2951 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:
The LP2950/51 unlike other low dropout regulators will remain
stable and 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
LP2950/51 version with external resistors, a minimum load of 1µA 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.
V
OUT = VREF × (1 + R1/R2)+ IFBR1
The VREF is 1.235 and IFB is the feedback bias current, nominally -
20nA. The minimum recommended load current of 1 µA forces an
upper limit of 1.2MΩ on value of R2. If no load is 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 LP2951
typically draws 60µA at no load with Pin 2 open-circuited this is a
small price to pay
Instability can occur if there is stray capacitance to the LP2951
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 3.3
µF.
4.75V
OUTPUT
VOLTAGE
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 3 lead LP2950 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
\
_______
ERROR*
+
+
5.0V
INPUT
VOLTAGE
+
1.3V
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.
* See Application Info.
Figure 1. ERROR Output Timing
ERROR DETECTION COMPARATOR OUTPUT
The Comparator produces a logic low output whenever the LP2951
output falls out of regulation by more than around 5%. This is around
60 mV offset divided by the 1.235 reference voltage. This trip level
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
8
LP2950/LP2951
TYPICAL APPLICATIONS
+V IN
100K
8
+V IN
______
ERROR
ERROR
5
1.2 to 30V
1
OUTPUT
V OUT
LP2951
+
SHUTDOWN
INPUT
3
R1
3.3µF
SD
.01µF
FB
GND
7
4
1.23V
V REF
R2
+V
IN
+V
IN
470kΩ
8
+V
______
ERROR
IN
5
V OUT
1
8
470kΩ
V OUT
+V
______
ERROR
IN
5
ERROR
*V
= V
IN
1
OUT
OUTPUT
LP2951
V OUT
+
3
R1
1µF
LP2951
SD
FB
GND
4
3
SHUTDOWN
INPUT
RESET
SD
7
FB
GND
7
4
R2
*MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40mV to 400mV.
DEPENDING ON LOAD CURRENT. CURRENT LIMIT IS TYPICALLY 150mA
Figure 3. Latch Off When Error Flag Occurs
Figure 4. Wide Input voltage Range Current Limiter
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
9
LP2950/LP2951
TYPICAL APPLICATIONS (continued)
+
6V
SEALED
1.5kΩ
120kΩ
LEAD-
8
ACID
1N457
BATTERY
SOURCE
+VIN
FB
SPX385
1
2
MAIN V+
OUT
V
LP2951
MEMORY V+
SENSE
400kΩ
+
FOR 5.5 V
3
20kΩ
1µF
SD
100kΩ
GND
4
NI-CAD
BACKUP
BATTERY
Figure 5. Low Battery disconnect
8
2
Ω
39k ..
SENSE
+V
_____IN_
ERROR
+VOUT = 5V
5
1
7
VOUT
RESET
+
1uF
LP2951
-
3
C4
+
SD
FB
TAP
Ω
39k ..
GND
4
6
Ω
100k
1%
..
Ω
100k
-
..
C1
C2
+
6V
LEAD-
ACID
Ω
..
1k
<5.8V**
<6.0V**
<6.2V**
1%
1%
Ω
-
100k
..
BATTERY
+
Ω
-
100k ..
Ω
1k
..
C3
+
Ω
10k
..
R3
* OPTIONAL LATCH OFF WHEN DROPOUT OCCURS. ADJUST R3 FOR C2 SWITCHING WHEN
VIN IS 6.0V
ESHHOLDS
Ω
1%
20k
Figure 6. Regulator with State-of Charge Indicator
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
10
LP2950/LP2951
TYPICAL APPLICATIONS (continued)
+V IN
8
10K
Ω
.
+V IN
_______
ERROR
5
1
5 DEGREE SHUTDOWN FLAG
3
AUX SHUTDOW
INPUT
.
SD
OFF
LP2951
ON
V
OUT
GND
FB
EXTERNAL CIRCUIT
PROTECTED FROM
4
7
OR
+
OVER TEMPERATURE
(V+ GOES OFF WHEN
TEMP > 125)
TEMP
SENSOR
AS35
RELAY
-
8.2K
Ω
Figure 7. System Over Temperature Protection
+5V
4.7mA
UNREGULATED INPUT
4
20mA
8
OUTPUT
8
330K
Ω
IN
1
+V IN
2N5432
(2)
VOUT
1
V OUT
27K
Ω
LP2951
1N4001
LP2951
2
5V
6
7
SENSE
0.1µF
VTAP
FB
2
OUTPUT
FB
7
GND
4
+
4.7µF
LOAD
50mA
GND
4
360K
Ω
TO
300 mA
1N457
MIN VOLTAGE = 4V
Figure 8. Open Circuit Detector for 4mA to 20mA Current
Loop
Figure 9. 300mA Regulator with 0.75V
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
11
LP2950/LP2951
SCHEMATIC DIAGRAM
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
12
LP2950/LP2951
PACKAGE DIAGRAM
TO-92 (N)
8-Pin Surface Mount (S)
2
1
3
1
2
8
7
INPUT
OUTPUT
SENSE
FEEDBACK
SHUTDOWN
3
4
6
5
5V or 3.3V Output
ERROR
V
V
GROUND
OUT
IN
GROUND
LP2950 Bottom View
LP2951 Top View
ORDERING INFORMATION
Ordering No. Accuracy Output Voltage
Packages
3 lead TO-92
3 lead TO-92
3 lead TO-92
3 lead TO-92
8 Lead SOIC
8 Lead SOIC
8 Lead SOIC
8 Lead SOIC
LP2950ACN-3.3
LP2950ACN-5.0
LP2950CN-3.3
LP2950CN-5.0
LP2951ACS-3.3
LP2951ACS-5.0
LP2951CS-3.3
LP2951CS-5.0
0.5%
0.5%
1%
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
1%
0.5%
0.5%
1%
1%
Now available in Lead Free. To order ad "-L" to the part number.
Example: LP2950CN= Normal, LP2950CN-L = Lead Free
C o rp o ra tio n
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation
Headquarters and Main Offices:
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 935-7600
FAX: (408) 934-7500
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it
convey any license under its patent rights nor the rights of others.
Rev. 8/10/01
LP2950/51 100mA Low Dropout Voltage Regulators
©Copyright 2001 Sipex Corporation
13
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