Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
100mA Low Dropout Voltage Regulator LP2950/LP2951
Pin Connection
TO-92 (Z)
Ordering Information
8SOIC (M)
Package Tolerance
0.5% 1%
TO-92 LP2950AZ-XX LP2950-BZ-XX
8SOIC LP2951AM-XX LP2951BM-XX
“XX” Voltag e Selection Guide
Vout XX Code
5.0V 5
3.3V 3.3
3.0V 3
Adjustable Left Blank
Description
The Bay Linear LP2950 and LP2951 are low power voltage
regulators. They are excellent choice for use in Battery
Powered applications such notebooks computers. The LP2950
and LP2951 feature low quiescent current ( 75µA Typ.) and
low dropout of 40mV at light loads 380mV (typ.) at 100mA.
With a tight initial tolerance of 0.5% typ., extremely good load
and line regulation of 0.05% typ. And very low output
temperat ur e coe ffici ent makin g th e LP29 50 an d LP2 95 1 u seful
as a low power reference.
The Bay Linear LP2950 is available in fixed voltages of 3.0V,
3.3V, and 5.0V in a TO-92 package.
The Bay Linear LP2951 comes in an 8SOIC package and has
an adjustable output voltage from 1.24V to 29V programmed
with a pair of external resistor. It also features pin-strap
capability providing the fixed voltage of 3.0, 3.3V or 5V for
conven ience. The LP 2951 has an error flag out put feature u sed
as power-on reset for warning of low output voltage due to
falling battery voltages. Also, the logic compatible shutdown
input enables the regulator to be switched ON and OFF.
Features
• Guaranteed 100mA Output
• 5.0V, 3.3V and 3.0V Versions
• Very Low Quiescent Current
• Low Dropout Voltage
• Extremely Tight Load and Line
Regulation
• Very Low Temperature Coefficient
• Needs only 1µ
µµ
µF for Stability
• Error Flag warns of output dropout
• Logic-Cont rolled Electronic Shutdown
• Output programmable from 1.24V to 29V
Applications
• Battery Powered Systems
• Portable instrumentation
• Notebooks Computers
• Potable Consumer Equipment
• Automotive electronics
• SMPS Post-Regulator
Bay Linear
Bay LinearBay Linear
Bay Linear
Linea r Exc e lle nc e
1
2
4
3
5
6
7
8
Output Input
Shutdown
Sense
-XX V tap
Feedback
Ground Error
Vout Vin
Grd
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LP2950/LP2951
Absolute Maximum Rating
Parameter
Power Dissipation Internally Limited
Lead Temperature ( Soldering 5 seconds ) 260 °C
Storage Temperature Range -65 °C to +150 °C
Operatin g Junction Temperatu r e -55 °C to +150 °C
Input Supply Voltage -0.3V to +30V
Feedbac k Input Voltage -1.5V to +30V
Shutdown Input Voltage -0.3V to +30V
Error Comparator Output -0.3V to +30V
Electrical Characteristics
(VS = 15V, TA = 25°C , unless otherwise specified)
Parameter Conditions MIN TYP MAX UNIT
Output Voltage -25 °C ≤ Tj ≤ 85 °C
Full Operat ing Temperatur e 0.985 [ Vo ]
0.98 [ Vo ]
Vo 1.015 [ Vo ]
1.02 [ Vo ]
V
Output Voltage 100µA ≤ I L ≤ 100mA, Tj ≤ T jmax 0.976 [Vo ] Vo 1.024 [ Vo ] V
Output Voltage Temperature
Coefficient (Note 1) 50 150 ppm / ° C
Line Regulation (Note 3) VO + 1V ≤ VIN ≤ 30V (Note 4) 0.04 0.4 %
Load Regulation (Note 5) 100µA ≤ IL ≤ 100mA 0.1 0.3 %
Dropout V oltag e IL = 100µA
IL = 100mA 50
380 80
450 mV
Ground Current IL = 100µA
IL = 100mA 75
8 120
12 µA
mA
Dropout Ground Current VIN = VO - 0.5V, IL = 100µA 110 170
µA
Current Limit VOUT = 0 160 200 mA
Thermal Regulation 0.05 0.2 % / W
Output Noise,
10Hz to 100KHz CL = 1µF
CL = 200µF
CL = 3.3µF
(Bypass = 0.01 µF pins 7 to 1 for
LP2951-XX)
430
160
100
µVrms
8 pin Versions only (LP2951)
Reference Vo ltage
Over temperatu r e 1.21
1.185 1.235 1.26
1.285 V
Feedback Pin Bias Current 20 40 ηA
Reference Voltage Temperature
Coefficient (Note 7) 50 ppm/°C
Feedback Pin Bias Current
Temperature Coefficient 0.1 100
ηA/°C
Error Comparator
Output Leakage Current VOH = 30V 0.01 1.0 µA
Output Low Voltage VIN 4.5V, IOL = 400µA 150 250 mV
Upper Threshold Voltage (Note 8) 40 60 mV
Lower Threshold Voltage (Note 8) 75 95 mV
Hysteresis (Note 8) 15 mV
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LP2950/LP2951
Parameter Conditions MIN TYP MAX UNIT
Shutdown Input
Inpu t Logic Voltage Low (Regulat or ON)
High (Regulator OFF)
2 1.3 0.7 V
Shutdown Pin Input Current VS = 5V
VS =3 0V 30
450 50
600 µA
Regulator Output Current
in Shutdown (Note 9)
VOUT = 5.0V
3.3V ≤ VOUT ≤ 5.0V
2.0V ≤ VOUT ≤ 3.3V
3
10
20
30
µA
Note 1: Output or referenc e voltage t emperature coeffici ents defined as the worst ca se voltage chan ge divid ed by the total temperatu r e range.
Note 2: Unless otherwise specif ied all lim its guaranteed for TJ = 25°C, VIN = VO +1V, IL = 100µA and CL = 1µF. Additional conditions for the 8-
pin versions are feedback tied to –XX Voltage tap and output tied to output Sense pin ( VOUT = XX V) and VSHUTDOWN ≤ 0.8 V
Note 3: Regulation is measured at constant jun ction temperat ure , usi ng pulse test ing with a low duty cycle. Changes in ou tput volta ge due to
heating effects are covered under specification for th ermal regulation.
Note 4: Line regulation for LP2951-XX is tested at 150°C for IL = 1mA. For IL = 100µA and TJ = 125°C, line regulation is guaranteed by d es ign
to 0.2%. See typical performance characteristics for line regulation versus temperature and load current.
Note 5: Dropout voltage is d efined as t he input to output di fferential at which the output voltage drops 100mV below its n ominal value measured
at 1V differential. At very low values of p r ogrammed output voltage, the minimum input supply voltage of 2 V (2.3V over t em perature) must be
taken into account.
Note 6: VREF ≤ VOUT ≤ (VIN –1V), 2.3V ≤ VIN ≤ 30V , 100µA ≤ IL ≤100mA , TJ ≤ TJMAX
Note 7: Output or referenc e voltage t emperature coeffici ent is defined as the worst ca se voltage change divid ed by the total temperat ure range
Note 8: Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nominal reference voltage
meas ured at VO + 1V input. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VOUT / VREF =
(R1 + R2)/R2. For exa mple, at a programmed output voltage of 5V, the error output is guaranteed to go low when the output drops by 95mV X
5V / 1.235V = 384mV . Thresh olds rema in constant as a p ercent of VOUT as VOUT is varied, wit h the dropout warning occurring at typ ically 5 %
below nominal, 7.5% guaranteed.
Note 9: VSHUTDOWN ≥ 2V, VIN ≤ 30V, VOUT = 0, Feed-back pin tied to –XX Voltage Tap.
Block Diagram
FEEDBACK INPUT OUTPUT
UNREGULATED DC
SHUTDOWN
GROUND
ERROR
______
5V TAP
SENSE
5V @ 150mA
MAX
TO CMOS OR
TTL
REFERENCE
ERROR DETECTION
COMPARATOR
ERROR
AMPLIFIER
1.23V
FROM
CMOS OR
TTL
+
+
+
+
+
+
60 mV
3
781
2
6
5
4
Ω..
60k
330k
180k
Ω..
Ω..
µ..1F
_
_
LP2950 and LP2951 Block Diagr am
FEEDBACK INPUT OUTPUT
UNREGULATED DCUNREGULATED DC
SHUTDOWN
GROUND
ERROR
______
5V TAP
SENSE
5V @ 150mA
MAX
5V @ 150mA
MAX
TO CMOS OR
TTL
TO CMOS OR
TTL
REFERENCE
ERROR DETECTION
COMPARATOR
ERROR DETECTION
COMPARATOR
ERROR
AMPLIFIER
ERROR
AMPLIFIER
1.23V
FROM
CMOS OR
TTL
FROM
CMOS OR
TTL
+
+
+
+
+
+
60 mV
3
781
2
6
5
4
Ω..
Ω..
60k
330k
180k
Ω..
Ω..
Ω..
Ω..
µ..
µ..1F
_
_
LP2950 and LP2951 Block Diagr am
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LP2950/LP2951
APPLICATION H INT S
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 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 in creas ed without lim it.
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 LP2950, 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
LP2951 version with external resistors, a minimum load of 1uA is
recommended.
If there is more than 10 inches of wire between the inp ut 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 LP2951
feedback terminal (pin 7). This could cause more problems when
usin g a higher va lue of ext ernal resis tors to set the ou tput voltage.
This problem can be fixed by adding a 100pF capacitor between
out put and feed back an d increa sing the ou tput capac itor to at least
3.3µF.
ERROR DETECTION COMPARATOR
OUTPUT
The Com parator produ ces a logic low output whenever t he
LP2951 output falls ou t of regulation by more than around 5%.
This is arou nd 60mV offs et divi ded by t he 1. 235 refer ence volt age.
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 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
LP2951’s dropout voltage is load dependent, the input voltage trip
point (around 5V) will vary with the load current. The output
voltage trip point (app rox. 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 res ist or may be r eturn ed t o 5V out put or ot her sup ply volt age i n
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 O UTPUT 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 b etwe en it s 1.235V referen ce and its 30 V maximum rat ing .
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 i s 1.235 and IFB is the feedback bias current, n o minally
-20 nA. The minimum recommended load current of 1µA fo rces an
upper limit of 1.2 MΩ on va lue of R2. If no load presented the IFB
prod uces an error of t ypica lly 2% i n 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.
REDUCIN G OUTPUT NOISE
It may be an advanta g e to reduce the AC noise present at th e 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 LP2950 but is relatively inefficient, as increasing the
capacitor from 1µF to 220 µF only decr eases t he n ois e from 4 30µV
to 160µVRMS. for a 100kHz bandwidth at 5V output.
Noise could also be reduced fourfold by a bypass capacitor across
R1, since it reduc es 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 redu ce the
output noise from 4 30µV 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.
+
+
+
+
4.75V
OUTPUT
VOLTAGE
ERROR*
_______
INPUT
VOLTAGE 1.3V
5.0V
Figure 1. ERROR Output Timing
_______
* See Application Info.
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylin ear.com
LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERI ST ICS
INPUT CURRENT (mA)
160
150
140
130
70
50
0
INPUT VOLTAGE (VOLTS)
GROUND PIN CURRENT (mA)
10
1
0.1
0.01
0.1 1 10 150
LOAD CURRENT (mA)
120
110
100
90
80
60
40
30
20
10
0
12345678910
INPUT CURRENT
QUIESCENT CURRENT
240
220
200
180
-75 -50 -25 0 25 50 75 100 125150
TEMPERATURE (ºC)
QUIESCENT CURRENT
QUIESCENT CURRENT (µA)
170
150
130
110
-75 -50 -25 0 25 50 75 100 125150
TEMPERATURE (ºC)
SHORT CIRCUIT CURRENT
SHORT CIRCUIT CURRENT (mA)
160
140
120
110
V
IN
=6V
I
L
=100mA
R
L
=50
Ω
600
400
300
50
-75 -50 -25 0 25 50 75 100 125 150
TEMPERATURE (ºC)
DROP-OUT VOLTAGE
DROP-OUT VOLTAGE (mV)
500
100
0
OUTPUT VOLTAGE (V)
5.06
5.04
5.0
TEMPERATURE (ºC)
OUTPUT VOLTAGE (VOLTS)
00
INPUT VOLTAGE (VOLTS)
5.02
4.98
4.96
4.94
OUTPUT VOLTAGE VS. TEMP OF 3
REPRESENTATIVE UNITS
DROPOUT CHARACTERISTICS
16
12
8
4
-75 -50 -25 0 25 50 75 100 125150
TEMPERATURE (ºC)
GROUND CURRENT
GROUND CURRENT (mA)
123456
1
2
3
4
5
6
-75 -50 -25 0 25 50 75 100 125 150
0.2%
I
L
= 100mA
I
L
= 100µA
R
L
=50k
Ω
R
L
=50k
Ω
V
IN
= 6V
I
L
= 100mA
~
~
INPUT CURRENT (µA)
75
0
010 150
INPUT VOLTAGE (VOLTS)
INPUT CURRENT
GROUND CURRENT (µA)
320
280
0
INPUT VOLTAGE (VOLTS)
240
80
40
012345678
GROUND CURRENT
16
14
12
012345678
INPUT VOLTAGE
GROUND CURRENT
GROUND CURRENT
R
L
= 50k
Ω
25
50
100
125
150
175
200
225
250
123
120
160
200
10
8
6
4
2
0
I
L
= 1mA
I
L
= 0
I
L
=100mA
T
J
= 25ºC
DROP-OUT VOLTAGE
OUTPUT CURRENT
DROP-OUT VOLTAGE (mV)
100mA
10mA
1mA100µA
500
400
300
200
100
0
R
L
=
8
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylin ear.com
LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
10
0.5
0.1
0.02
10 100 1K 10K 100K 1M
FREQUENCY (Hz)
OUTPUT IMPEDANCE
OUTPUT IMPEDANCE (OHMS)
5
0.2
0.05
0.01
90
70
60
40
10
1
10
2
10
3
10
4
10
5
10
6
FREQUENCY (Hz)
RIPPLE REJECTION
RIPPLE REJECTION (dB)
80
50
20
RIPPLE REJECTION
FREQUENCY (Hz)
RIPPLE REJECTION (dB)
10
6
10
3
10
2
10
1
90
80
70
60
50
20
1
2
30
I
L
= 100µA
I
L
= 0
C
L
= 1µF
V
IN
= 6V
V
OUT
= 5V
40
30
10
4
10
5
I
L
= 10mA
I
L
= 10mA
C
L
= 1µF
V
IN
= 6V
V
OUT
= 5V
I
O
= 100mA
I
O
= 100µA
I
O
= 1mA
V
OUT
= 5V
C
L
= 1µF
COMPARATOR OUTPUT (V)
8
6
0
INPUT VOLTAGE (V)
4
2
0
-2
12345
ERROR COMPARATOR OUTPUT
SINK CURRENT (mA)
2.5
1.5
OUTPUT LOW VOLTAGE (V)
2.0
1.0
0.5
0.0
COMPARATOR SINK CURRENT
TIME(µs)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
V
OUT
= 5V
PULLUP RESISTOR TO
SEPARATE 5V SUPPLY
HYSTERESIS
100
0 200 400 600 800
LINE TRANSIENT RESPONSE
INPUT OUTPUT VOLTAGE
VOLTAGE CHANGE
4V
6V
8V
-50
0
50
~
~
mV
mV
mV
C
L
= 1µF
I
L
= 1mA
V
OUT
= 5V
T
A
= -55ºC
T
A
= 25ºC
T
A
= 125ºC
LP2951
7
6
4
-100 0100 200 300 400 500 600 700
TIME
ENABLE TRANSIENT
SHUTDOWN OUTPUT
PINOUT VOLTAGE (V) VOLTAGE (V)
3
2
1
0
2
-2
250
100
-50
100
012345
TIME (ms)
LOAD TRANSIENT RESPONSE
LOAD OUTPUT VOLTAGE
CURRENT CHANGE (mV)
µA
~
~
mA
-100
0
50
150
200
C
L
= 1µF
V
OUT
= 5V
80
20
-40
100
048121620
TIME (ms)
LOAD TRANSIENT RESPONSE
LOAD OUTPUT VOLTAGE
CURRENT CHANGE (mV)
µA
100
-60
-20
0
40
60
µA
C
L
= 1µF
V
OUT
= 5V
0
5
C
L
= 10µF V
OUT
= 5V
V
IN
= 8V
I
L
= 10mA
100
~
~
MINIMUM OPERATING VOLTAGE (V)
10
1
0.1
0.01
-75 0 75 150
TEMPERATURE
MINIMUM OPERATING VOLTAGE
BIAS CURRENT (nA)
-30-75
TEMPEATURE (ºC)
FEEDBACK BIAS CURRENT
FEEDBACK CURRENT (µA)
-150
-250
-2.0 -0.5 1.0
FEEDBACK VOLTAGE (V)
FEEDBACK PIN CURRENT
-50 0 50 75 100 150
-20
-10
0
10
20
-200
-100
-50
0
50
-1.5 -1.0
-50 -25 25 50 100 125 -25 25 125 0 0.5
T
A
= 25ºC
T
A
= 55ºC
T
A
=1 25ºC
LP2951 LP2951 LP2951
PIN 7 DRIVEN BY EXTERNAL
SOURCE (REGULATOR RUN
OPEN LOOP)
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylin ear.com
LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VOLTAGE NOISE
SPECTRAL DENSITY (µV/Hz)
3.5
2.5
2.0
0.0
10
2
10
3
10
4
10
5
FREQUENCY (Hz)
OUTPUT NOISE
I
L
= 100mA
C
L
= 1µF
C
L
= 220µF
C
L
= 3.3µF
3.0
1.5
1.0
0.5
OUTPUT CURRENT (mA)
120
100
60
40
0
INPUT VOLTAGE (V)
80
20
0
510 15202530
LP2950 MAXIUM RATED OUTPUT
CURRENT
T
JMAX
= 125º C
V
OUT
= 5V
T
A
= 25ºC
T
A
= 50ºC
T
A
= 85ºC
8-PIN
MOLDED
DIP SOLDERED
TO PC BOARD
SHUTDOWN THRESHOLD VOLTAGE (V)
1.8
1.6
1.0
-75
TEMPERATURE (ºC)
1.4
1.2
0.8
0.6
-50 -25 0 25 50 75 100 125 150
SHUTDOWN THRESHOLD VOLTAGE
OUTPUT CURRENT (mA)
120
80
0
010 20 30
INPUT VOLTAGE (V)
LP2950 MAXIUM RATED OUTPUT
25155
T
A
= 85 ºC
T
A
=25 ºC
T
JMAX
= 125 ºC
0.25" LEADS SOLDERED
TO-92 PACKAGE
TO PC BOARD
100
60
40
20
RIPPLE REJECTION (dB)
80
60
40
10
10
1
10
3
10
4
10
6
FREQUENCY (Hz)
RIPPLE REJECTION
I
L
= 50µA
I
L
= 100mA
C
L
= 1µF
V
IN
= 6V
V
OUT
= 5V
70
50
30
20
10
2
10
5
OUTPUT VOLTAGE CHANGE (mV)
30
25
20
10
5
INPUT VOLTAGE (V)
15
10
5
0
5
0
-5
-10
10 15 20 25 30
LINE REGULATION
~
~
I
L
= 100µA
I
L
= 1mA
T
J
= 150 ºC
T
J
= 125 ºC I
L
= 100µA
PIN 2 TO PIN 4 RESISTANCE (k
Ω)
Ω)Ω)
Ω)
400
200
100
0
-75 0 75 150
TEMPERATURE (ºC)
LP2951 DIVIDER RESISTANCE
-50 -25 25 50 100 125
300
POWER OUTPUT VOLTAGE
DISSIPATION (W) CHANGE (mV)
4
2
1
0
TIME (µs)
0
-2
0
-1
10 20 30 40 50
THERMAL RESPONSE
5
1.25W
~
~
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylin ear.com
LP2950/LP2951
TYPICAL APPLICATIONS (continued)
100K
SENSE
SD
VOUT
GND
+VIN
3
8
1
1uF
+
4
Ω..
Ω..
400K
120K 1.5KΩ..
Ω..
6V
SEALED
LEAD-
ACID
BATTERY
SOURCE FB
FOR 5.5 V
+
1N457
2Ω..
20K
NI-CAD
BACKUP
BATTERY
MEMORY V+
MAIN V-
LM385
Low Battery Disconnect
BAY
LP2951
100K
SENSE
SD
VOUT
VOUT
GND
+VIN
+VIN
3
8
1
1uF
+1uF
+
4
Ω..
Ω..
Ω..
Ω..
400K
120K 1.5KΩ..
Ω..
Ω..
Ω..
6V
SEALED
LEAD-
ACID
BATTERY
SOURCE
6V
SEALED
LEAD-
ACID
BATTERY
SOURCE FB
FOR 5.5 V
+
1N457
2Ω..
Ω..
20K
NI-CAD
BACKUP
BATTERY
NI-CAD
BACKUP
BATTERY
MEMORY V+
MAIN V-
LM385
Low Battery Disconnect
BAY
LP2951
GND
4
3
5
82
1
7
6
SD
TAP
FB
+VIN SENSE
VOUT
ERROR
______
RESET
100k
100k
100k
1k
100k
10k
20k
1k
39k
39k
C3
C1
C2
C4
1%
1%
1%
1%
6V
LEAD-
ACID
BATTERY
R3
<6.2V**
<5.8V**
<6.0V**
-
+
+
+
+
-
-
-
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
+VOUT = 5V
1uF
+
Regula to r with State-of-Ch a rge indicato r
* OPTIONAL LATCH OFF WHEN DROPOUT OCCURS. ADJUST R3 FOR C2 SWITCHING WHEN
VIN IS 6.0V
** OUTPUTS GO LOW WH EN V
IN DROPS BELOW DESGNATED THRESHHOLDS
BAY
LP2951
GND
4
3
5
82
1
7
6
SD
TAP
FB
+VIN
+VIN SENSE
VOUT
VOUT
ERROR
______
RESET
100k
100k
100k
1k
100k
10k
20k
1k
39k
39k
C3
C1
C2
C4
1%
1%
1%
1%
6V
LEAD-
ACID
BATTERY
6V
LEAD-
ACID
BATTERY
R3
R3
<6.2V**<6.2V**
<5.8V**<5.8V**
<6.0V**<6.0V**
-
+
+
+
+
-
-
-
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
Ω..
+VOUT = 5V+VOUT = 5V
1uF
+
Regula to r with State-of-Ch a rge indicato r
* OPTIONAL LATCH OFF WHEN DROPOUT OCCURS. ADJUST R3 FOR C2 SWITCHING WHEN
VIN IS 6.0V
** OUTPUTS GO LOW WH EN V
IN DROPS BELOW DESGNATED THRESHHOLDS
* OPTIONAL LATCH OFF WHEN DROPOUT OCCURS. ADJUST R3 FOR C2 SWITCHING WHEN
VIN IS 6.0V
** OUTPUTS GO LOW WH EN V
IN DROPS BELOW DESGNATED THRESHHOLDS
BAY
LP2951
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylin ear.com
LP2950/LP2951
TYPICAL APPLICATIONS (continued)
EXTERNAL CIRCUIT
PROTECTED FROM
OVER TEMPERATURE
(V+ GOES OF F WHEN
TEMP > 125)
OR
RELAY
8.2K
TEMP
SENSOR
GND
VOUT
FB
SD
+VIN
+VIN
10K
5 DEGREE SHUTDO WN FLAG
ERROR
_______
35
8
47
1
AUX SHUTD OW
INPUT OFF
ON
Ω..
LM35
+
-
System Over Temperature Protection Circuit
BAY
LP2951
Ω..
EXTERNAL CIRCUIT
PROTECTED FROM
OVER TEMPERATURE
(V+ GOES OF F WHEN
TEMP > 125)
EXTERNAL CIRCUIT
PROTECTED FROM
OVER TEMPERATURE
(V+ GOES OF F WHEN
TEMP > 125)
OR
RELAY
8.2K
TEMP
SENSOR
TEMP
SENSOR
GND
VOUT
VOUT
FB
SD
+VIN
+VIN
+VIN
+VIN
10K
5 DEGREE SHUTDO WN FLAG
ERROR
_______
35
8
47
1
AUX SHUTD OW
INPUT
AUX SHUTD OW
INPUT OFF
ON
Ω..
Ω..
LM35
+
-
System Over Temperature Protection Circuit
BAY
LP2951
Ω..
Ω..
360K
0.1uF
VOUT
MIN VOLTAGE = 4V
+VIN
8
1
FB 7
1N4001
20mA
1N457
4.7mA
+5V
OUTPUT
2
GND
4
4
Open Circuit Detector for 4mA to 20mA Current Loop
BAY LINEAR
LP2951
Ω..
360K
0.1uF
VOUT
VOUT
MIN VOLTAGE = 4V
+VIN
+VIN
8
1
FB 7
1N4001
20mA
1N457
4.7mA
+5V
OUTPUT
2
GND
4
4
Open Circuit Detector for 4mA to 20mA Current Loop
BAY LINEAR
LP2951
Ω..
Ω..
330K
IN VOUT
FB
3
5
1
4.7uF
+
7
Ω..
Ω..
27K
BAY LINEAR
LP2951
VTAP GND
SENSE
4
2
UNREGULATED INPUT
2N5432
5V
OUTPUT
LOAD
50mA
TO
300 mA
300 mA Regul ator w ith 0.75 D r opout
330K
IN VOUT
VOUT
FB
3
5
1
4.7uF
+
7
Ω..
Ω..
Ω..
Ω..
27K
BAY LINEAR
LP2951
VTAP
VTAP GND
SENSE
4
2
UNREGULATED INPUT
2N5432
5V
OUTPUT
5V
OUTPUT
LOAD
50mA
TO
300 mA
LOAD
50mA
TO
300 mA
300 mA Regul ator w ith 0.75 D r opout
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylin ear.com
LP2950/LP2951
SCHEMATIC DIAGRAM
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylin ear.com
LP2950/LP2951
Package Drawing
SO-8 (M)
Pin 1
1.27 (0.50)
BSC
3.8 (0.150)
4.0 (0.158) 4.6 (0.181)
5.2 (0.205) 5.8 (0.228)
6.2 (0.244)
4.8 (0.188)
5.0 (0.197)
0.49 (0.019)
0.56 (0.022)
0.35 (0.014)
0.45 (0.018)
0.10 (0.004)
0.20 (0.008) 0.19 (0.007)
0.22 (0.009)
1.35 (0.053)
1.75 (0.069)
0.61 (0.024)
0.78 (0.031)
3
°
-6
°
0.64 (0.025)
0.77 (0.030)
45
°
7
°
(4 PLCS)
7
°
(4 PLCS)
0.37 (0.015)
BSC
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylin ear.com
LP2950/LP2951
PACK AG E DR AW I NG
TO-92(Z)
Advance Information- These data sheets contain descriptions of products that are in development. The specifications are based on the engineering calculations,
computer simulations and/ or initial prototype evaluation.
Preliminary Information- These data sheets conta in minimum and maximum specificat io ns that are based on the initial device characterizations. These li mits are
subject to change upon the completion of the full characterization over the specified temperature and supply voltage ranges.
The applicati on circuit examples ar e only to explain the representati ve applicatio ns of the devices and ar e not intended to guarantee any c ircuit
desi gn or permit any industrial prop erty right to other rights to execute. Bay Linear takes no responsibility for any prob lems related to any
industrial property right resulting from the use of th e conten ts shown in the data book. Typical parameters can and do vary in different
applications. Customer’s technical experts must validate all operating parameters including “ Typical” for each customer application.
LIFE SUPPORT AND NUCLEAR POLICY
Bay Linear products are not authorized for and should not be used within life support systems which are intended for surgical
implants into the body to support or sustain life, in aircraft, space eq uipment, submarine, or nuclear facility applications without
the specific written consent of Bay Linear President.
1
2
3
0.055 (1.397)
0.045 (1.143)
0.145 (3.683)
0.135 (3.429)
10° typ.
BOTTOM VIEW
0.185 (4.699)
0.045 (1.143)
0.185 (4.699)
0.175 (4.445)
0.085 (2.159) Diameter
0.090 (2.286) typ.
Seating Plane
0.016 (0.406)
0.014 (0.356)
0.055 (1.397)
0.045 (1.143)
0.105 (2.667)
0.095 (2.413)
0.500 (12.70) Min.
0.025 (0.635) Max
Uncontrolled
Lead Diameter
5° typ.
5° typ.
0.090 (2.286) Radius typ.
0.0155 (0.3937)
0.0145 (0.3683)
