PJ2950/PJ2951
150mA Low Dropout Voltage Regulators
T
he Semiconductor PJ2950 and PJ2951 are a low power
voltage regulators. These devices are excellent choi ce
in battery-powered applications such as cordless
The error flag output feature is used as power-on reset
for warn of a low output voltage , due to following batteries
on input. Other feature is the logic-compatible shutdown
input which enable the regulator to be switched on and off.
The PJ2950 is offered in 3-pin TO-92 package compatible
with other 5 volt regulators. The PJ2951 is available in 8-pin
plastic, SOP-8 package.
The regulator output voltage may be pin-strapped fo r a
5 & 3.3 volt of programmed from 1.24 volt to 29 volts with
external pai r of resistors. Using of as design, processing and
testing techniques make our PJ2950 and PJ2951 superior
over similar products.
for use
telephone, radio control systems, and portable computers.
The PJ2950 and PJ2951 features very low quiescent
current (75μA Typ.) and very low drop output voltage
(Typ. 40μV at light load and 380 mV at 100 mA).This
includes a tight initial tolerance o f 0.5% typ., extremely
good load and line regulation 0.05% typ. and very low
output temperature coeffi cient, making the PJ2950/PJ2951
useful as a low-power voltage reference. Other key
additional feature of this unregulated input voltage transient
of -20V below ground (reverse battery).
____________________________________________________________________________________________________
FEATURES
•
•
•
•
•
•
•
•
Output accuracy 5V & 3.3V, 150 mA output
Very low quiescent current
Low dropout voltage
Extremely tight load and line regulation
Very low temperature coefficient
Need only 1μF for stability
Unregulated DC input can withstand -20V reverse
battery and +60V positive transients
Direct replacem ent for PJ2950/PJ2951 sockets
SOP-8
TO-92
PJ2950/2950A
Pin 1. Output
2. Ground
3. Input
PJ2951/2951A
Pin
1. Output
2. Sense
3. Shutdown
4. Ground
5. Error
6. 5 Vtap
7. Feedback
8. Input
PJ2951 VERSIONS ONLY
•
•
•
Error Flag warns of output dropout
Logic-Controlled electronic shutdown
Output programmable from 1.24 to 29V
ORDERING INFORMATION
Device
P J2950ACT
APPLICATIONS
•
•
•
•
•
•
•
•
•
•
Operating Temperature
Packag e
TO-92
Battery powered systems
Portable instrumentation
Avionics
Automotive Electronics
SMPS Post-Regulator
Voltage Reference
Portable/Palm top / Notebook computers
Portable consumer equipment
Radio control systems
Cordless telephones
PJ2950CT
PJ2950ACT-3.0
PJ2950CT-3.0
PJ2950ACT-3.3
PJ2950CT-3.3
PJ2951ACS
PJ2951CS
PJ2951ACS-3.3
PJ2951CS-3.3
-20 ~ +85
℃
SOP-8
1-7
2002/01.rev.A
PJ2950/PJ2951
150mA Low Dropout Voltage Regulators
ABSOLUTE MAXIMUM RATINGS
Power Dissipation......................Internally Limited
Lead Temp.(Soldering, 5 Seconds)................260℃
Storage Temperature Range.............-65 to +150℃
Operating Junction Temperature Range
PJ2951........................................….. -20 to +125℃
PJ2950A / PJ2950
PJ2951A / PJ2951...................…......-20 to +125℃
Input Supply Voltage.......................….. -20 to +60V
Feedback Input Voltage.........................-1.5 to +30V
Shutdown Input Voltage......................... -0.3 to+30V
Error Comparator Output...................…..-0.3 to +30V
ECD Rating is to be determined
ELECTRICAL CHARACT ERISTICS at V
s
=15V, Ta=25
℃
, unless otherwise noted.
CONDITIONS
(Note 2)
T
J
=25
℃
-25
℃
≤
T
J
≤85
℃
Full Operating Temp.
100μA≤ I
L
≤100mA
T
J
≤
T
JM AX
(Note 1)
PJ2950A/PJ2951A
Min
Typ
Max
PJ2950/PJ2951
Typ
UNITS
PARAMETER
Output Voltage
Min
Max
Output Voltage
Output Voltage
Temperature
Coefficient
Line Regulation
(Note 3)
Load Regulation
(Note 3)
Dropout Voltage
(Note 5)
Ground Current
0.995|Vo|
0.990|Vo|
0.988|Vo|
0.986|Vo|
5.0 / 3.3
/ 3.0
1.005|Vo|
1.010|Vo|
1.012|Vo|
1.014|Vo|
0.990|Vo|
0.985|Vo|
0.983|Vo|
0.985|Vo|
5.0 / 3.3 /
3.0
1.010|Vo|
1.015|Vo|
1.017|Vo|
1.015|Vo|
V
V
ppm/
℃
20
50
6V≤V
in
≤30V
(Note 4)
100μA≤I
L
≤100mA
I
L
=100μA
I
L
=100mA
I
L
=150mA
I
L
=100μA
I
L
=100mA
I
L
=150mA
V
in
=4.5V, I
L
=100μA
V
out
=0
C
L
=1μF
C
L
=200μF
C
L
=13.3μF
(Bypass=0.01μF
pins 7 to 1 P J2951)
0.03
0.04
40
250
300
75
1.7
4
110
150
0.05
430
160
100
0.2
0.1
80
300
450
120
2.5
6
170
200
0.2
0.04
0.1
40
250
300
75
1.7
4
110
150
0.05
430
160
100
0.2
0.2
80
300
450
120
2.5
6
170
200
0.2
%
%
mV
mV
mV
μ
A
mA
mA
μ
A
mA
%W
μ
Vms
Dropout Ground
Current
Current Limit
Thermal Regulation
Output Noise,
10Hz to 100KHz
8-Pin Versions only
Reference Voltage
Reference Voltage
Feedback Pin Bias
Current
Reference Voltage
Temperature
Coefficient
Feedback Pin Bias
Current
Temperature
Coefficient
Over Temperature
(Note 6)
PJ2951A
PJ2951
1.238
1.19
1.250
1.262
1.27
40
1.238
1.18
1.250
1.262
1.28
40
V
V
nA
ppm/
℃
20
(Note 7)
20
50
20
0.1
0.1
nA/℃
2-7
2002/01.rev.A
PJ2950/PJ2951
150mA Low Dropout Voltage Regulators
APPLICATION HINTS EXTERNAL CAPACITORS
CONDITIONS
(Note 2)
PJ2950A/PJ2951A
Min.
T yp.
Max
PJ2950/PJ2951
Min.
Typ.
Max
PARAMETER
UNITS
Error Comparator
Output Leakage
Current
Output Low
Voltage
Upper Threshold
Voltage
Power Threshold
Voltage
Hysteresis
Shutdown Input
Output Logic
Voltage
Shut down Pin
Input Current
Regulator Output
Current in
Shutdown
V
oh
=30V
V
in
= 4.5V
I
ol
= 400μA
(Note 8)
(Note 8)
(Note 8)
Low (Regulator ON)
High(Regulator
OFF)
Vs =2.4V
Vs = 30V
(Note 9)
0.01
150
40
60
75
15
1.3
2
30
450
3
1
250
40
95
150
60
75
15
0.7
2
50
600
10
30
450
3
1.3
1
250
μA
mV
mV
95
mV
mV
0.7
V
50
600
10
μA
μA
Note 1: Output or reference voltage temperature coeffi cients
defined as the worst case voltage change divided by the total
temperature range.
Note 2: Unless otherwise specified all limits guaranteed fo r
T
j
=25℃, V
in
=6V,I
L
=100μA and C
L
=100μF. Additional
conditions for the 8-pin versions are feedback tied to 5V &
3.3V tap output Sense (Vout =5V & 3.3V) and V
shutdown
≤
0.8V.
Note 3:Regulation is measured
Changes in output
at
constant junction
temperature , using pulse testing with a low duty cycle.
voltage due to heating effects are
convered under the speci fication for therm al regulation.
Note 4:Line regulation for the PJ2951 is tested at 150℃ for
I
L
=1mA.For I
L
=100μ A and Tj=125℃ , line regulation is
guaranteed by design to 0.2%. See typical
load current .
Note 5:Dropout Voltage is defined as the input to output
differential at which the output voltage drops 100mV b elow
its nominal value measured at 1V differential at very low
value o f programmed output voltage , the minimum input
perfo rmance
characteristics for line regulation versus temperature and
supply voltage of
taken in to account .
2V (2.3V over temperature) must be
Note 6: V
ref
≤
V
out
≤
(Vin-1V),2.3
≤
Vin
≤
30V, 100μA
≤
I
L
≤
100mA, T
J
≤
T
JMAX..
Note 7: Output or reference voltage temperature coeffi cient
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
For example, at a
output is
gain=Vout/Vref=(R1+R2)/R2.
programmed output voltage of 5V, the Error
guaranteed to go low when the output drops by 95 mV
X
5V/1.250=384mV. 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:V
shutdown
≡2V,
Vin
≤
30V,Vout =0, Feedback pin tied
to 5V & 3.3VTap.
3-7
2002/01.rev.A
PJ2950/PJ2951
150mA Low Dropout Voltage Regulators
PROGRAMMING THE OUTPUT VOLTAGE OF PJ2951
External Capacitors
For
the
stability
of
the
less output capacitance is required
for stability. For the currents below
10 mA the value of capacitor can be
reduce to 0.33μ F and 0.1μ F for
1mA.
More
output
capacitance
voltage setting with minimum load
of 1
μA
and external resistors.
If at the input of PJ2950/LP
2951 connected to battery or between
AC filter capacitor and input is 10
inches wire then 1μ F tantalum or
aluminum
electrolytic
capacitor
PJ2950/PJ2951 requires a 1.0
μF
or
greater capacitor between output and
ground.
Oscillation
could
occur
without this capacitor. The tantalum
or aluminum electrolytic works fine;
could use the fiLP type but are not
cost effi cient. For the operation of
below -25
℃
recommended
solid tantalum is
since
the
many
needed for the 8-pin version at
voltage below 5V since it runs the
error amplifi er at lower gain. At
worst case 3.3μF or greater must be
used for condition of 100mA load at
1.250V output .
The PJ2950 not like other low
dropout regulators will remain stable
and regulation with no load in
addition
to the internal
voltage
should be connect ed between input
and ground .
Instability can occur
if stray
aluminum type have electrolytes the
freeze at about -30℃. The ESR of
about 5
Ω
or less and resonant
capacitor to feedback terminal pin 7
of the PJ2951. This could cues more
problem more when using
higher
frequ ency above 500KHz are most
important parameter in the value of
Capacitor. The Capacitors value can
be increas ed without any limit.
At lower values of output current,
value of external to set the output
voltage . To fix this problem the 100
pF capacitor between output and
feedb ack
and
increasing
output
divider. This feature very important
in application like CMOS RAM
keep-alive.
The
PJ2951
output
capacitance to 3.3μF.
ERROR DETECTION COMPARATOR OUTPUT
The Compactor produces a logic
low output whenever the PJ2951
output falls of regulation by more
than around 5% . This is around 60
mV offs et divided by the 1.250
reference voltag e. Thus trip remains
5% below nominal regardl ess of the
programmed output voltage of the
regulator . the figure 1 shows the
timing
diagram
depicting
the
signal becomes low at around 1.3 V
input , it goes high around 5Volt
input , (input voltage at which Vout
= 4.75). The PJ2951 dropout voltage
depending on the load , the input
voltage trip point around 5 volt will
vary with load current. The output
voltage trip point is around 4.75 volt
it does not change with load.
The error comparator has an open-
collector output which requires an
external
pull-up
resistor.
Depending
requirem ent
on
the
system
the resistor maybe
returned to 5 or 3.3 volt output or
other supply voltage depending to
the
system
requirements.
For
determining the size of the resistor,
note that the output is sinking 400μ
A , this value adds to battery drain in
a low better condition, recommended
values 100K to 1MΩ. If the output
is unused this resistor
is not required.
ERROR signal and the regulator
output voltage as the PJ2951 input is
ramped up and down . the ERROR
4-7
2002/01.rev.A
PJ2950/PJ2951
150mA Low Dropout Voltage Regulators
The
PJ2951
output
voltage
is
Refer to the below equation for the
programming the output voltage:
Volt = V
ref
x (1+R
1
\R
2
)+I
FB
R
1
The V
ref
is 1.250 and I
FB
is the
maybe
eliminated
at
room
programmable for any value from it
reference voltage of 1.250 volt
and it maximum rating of 30 volt .
For example for 5 volt needs to pin-
strapped
and
using
the internal
temperature by trimming R
1
. To
improve the accuracy chooses the
value of
R2 =100K
and this
feedb ack bias current , nominally -20
nA. The minimum recommended
load current of 1μA forces an upper
limit of 1.2MΩ on value of R
2
, If
no load presented the I
FB
produces
error of typically 2% in Vout which
reduces the error by 0.17% and
increas es
the
resistor
program
voltage divider by tying pin 1 to 2
and pin 7 to pin
6. Refer to Figure
current by 12
μ
A . The PJ2951
typically draw 60
μA
at no load
with
pin
2 open-circuit,and this
2, there are two ext ernal resistor
required for this programming .
value does not look much .
REDUCING OUTPUT NOISE
It could be an advantage to reduce
the AC noise present at the output
One way is to reduce the regulator
bandwidth by increasing the value of
the output capacitor . this is the only
method that noise could reduce on
the
PJ2950
but
is
relatively
rms . for a 100KHz bandwidth at 5
volt output .
Noise could be also reduce by
fourfold by a
bypass capacitor
stability . These changes the output
noise from 430μV rms . for a 100
kHz bandwidth 5 & 3.3 volt output.
With the bypass capacitor added,
noise no longer scales with output
voltage so that improvements
more
voltage .
dramatic
higher
are
across R
1
since it reduces the high
frequency gain from 4 to unity . pick
CBYPASS = 1 / 2πR1 x 200Hz or
choose 0.01
μF
. When doing this,
the
output
capacitor
must
be
output
inefficient
, as increasing capacitor
from 1μF to 220μF only decreas es
the noise from 430μV to 160
μV
increas ed
to 3.3
μF
to maintain
FIGURE 1.ERROR OUTPUT TIMING
FIGURE 2.ADJUSTABLE REGULATOR
PJ2951
5-7
2002/01.rev.A
京公网安备 11010802033920号
EEWORLD
