PJ2950/PJ2951

150mA Low Dropout Voltage Regulators

1-6 2002/01.rev.A

he Semiconductor PJ2950 and PJ2951 are a low power
voltage regulators. These devices are excellent choice

for use in battery-powered applications such as cordless
telephone, radio control systems, and portable computers.
The PJ2950 and PJ2951 features very low quiescent
current (75A Typ.) and very low drop output voltage
(Typ. 40V at light load and 380 mV at 100 mA).This
includes a tight initial tolerance of 0.5% typ., extremely
good load and line regulation 0.05% typ. and very low
output temperature coefficient, 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).

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 for a
5, 3 & 3.3 volt of programmed from 1.24 volt to 29 volts
with external pair of resistors. Using of as design,
processing and testing techniques make our PJ2950 and
PJ2951 superior over similar products.

____________________________________________________________________________________________________

· Output versions available 5V, 3V & 3.3V
· Extremely low quiescent current
· Low dropout voltage
· Extremely tight load and line regulation
· Very low temperature coefficient
· Need only 1F for stability
· Unregulated DC input can withstand -20V reverse

battery and +60V positive transients

· Use as Regulator or Reference
· Stable with low-ESR output capacitors
· Current and Thermal Limiting
· Direct replacement for PJ2950/PJ2951 sockets

PJ2951 VERSIONS ONLY

· Error Flag warns of output dropout
· Logic-Controlled electronic shutdown
· Output programmable from 1.24 to 29V

Battery powered systems

Portable instrumentation

Avionics

Automotive Electronics

SMPS Post-Regulator

Voltage Reference

Portable/Palm top / Notebook computers

Portable consumer equipment

Radio control system

Device Operating

Temperature

(Ambient)

Package

PJ2950ACT

PJ2950CT

PJ2950ACT-3.0

PJ2950CT-3.0

PJ2950ACT-3.3

PJ2950CT-3.3

TO-92

PJ2951ACS

PJ2951CS

PJ2951ACS-3.3

PJ2951CS-3.3

-20 ~ +85

SOP-8

FEATURES

APPLICATIONS

TO-92

SOP-8

Pin
1. Output 5. Error
2. Sense 6. 5 Vtap
3. Shutdown 7. Feedback
4. Ground 8. Input

Pin 1. Output
2. Ground
3. Input

ORDERING INFORMATION

PJ2950/2950A

PJ2951/2951A

PJ2950/PJ2951

150mA Low Dropout Voltage Regulators

2-6 2002/01.rev.A

Power Dissipation......................Internally Limited Input Supply Voltage............................ -0.3 to +30V
Lead Temp.(Soldering, 5 Seconds)................260 Feedback Input Voltage.........................-1.5 to +30V
Storage Temperature Range.............-65 to +150 Shutdown Input Voltage......................... -0.3 to+30V
Operating Junction Temperature Range Error Comparator Output........................-0.3 to +30V
PJ2951............................................. -40 to +125 ECD Rating is to be determined
PJ2950A/PJ2950/PJ2951A/PJ2951...-40 to +125

PJ2950A/PJ2951A PJ2950/PJ2951

PARAMETER

CONDITIONS

(Note 2)

Min Typ Max Min Typ Max

UNIT

3V VERSIONS

=25

2.985 3.0 3.015 2.970 3.0 3.030

-25

2.970 3.0 3.030 2.955 3.0 3.045

Output Voltage

Full Operating Temp.

2.964 3.0 3.036 2.940 3.0 3.060

Output Voltage

100A

100mA

JMAX

2.958 3.0 3.042 2.928 3.0 3.072 V

3.3V VERSIONS

=25

3.284 3.3 3.317 3.267 3.3 3.333

-25

3.267 3.3 3.333 3.251 3.3 3.350

Output Voltage

Full Operating Temp.

3.260 3.3 3.340 3.234 3.3 3.366

Output Voltage

100A

100mA

JMAX

3.254 3.3 3.346 3.221 3.3 3.379

5V VERSIONS

=25

4.975 5.0 5.025 4.95 5.0 5.05

-25

4.95

5.0

5.05

4.925

5.0

5.075

Output Voltage

Full Operating Temp.

4.94 5.0 5.06 4.90 5.0 5.10

Output Voltage

100A

100mA

JMAX

4.925 5.0 5.075 4.88 5.0 5.12

ALL VOLTAGE OPTIONS

Output Voltage
Temperature Coefficient

(Note 1)

-- 20 100 -- 50 150

ppm/

Line Regulation (Note 3)

30V (Note 4)

-- 0.03

0.2 -- 0.04 0.2 %

Load Regulation (Note 3)

100A

100mA

-- 0.04

0.2 -- 0.1 0.3 %

Dropout Voltage
(Note 5)

=100A

=100mA

-- 50

380

450

-- 50

380

450

mV
mV

Ground Current

=100A

=100mA

-- 75

120

-- 75

120

Dropout Ground Current

=4.5V, I

=100A

-- 110 170 -- 110 170

Current Limit

out

-- 160 200 -- 160 200 mA

Thermal Regulation

-- 0.05

0.2 -- 0.05 0.2 %W

Output Noise,
10Hz

to 100KHz

(Bypass=0.01F
pins 7 to 1 PJ2951)

=1F

=200F

=3.3F

-- 430

160
100

-- --

430
160
100

Vms

8-Pin Versions only

PJ2950A/PJ2951A

PJ2950/PJ2951

Reference Voltage

1.235 1.250

1.260 1.235 1.250 1.260 V

Reference Voltage

Over Temperature(Note6)

1.19 -- 1.27 1.185 -- 1.285 V

Feedback Pin Bias Current

-- 20 40 -- 20 40 nA

Reference Voltage
Temperature Coefficient

(Note 7)

-- 20 -- -- 50

ppm/

Feedback Pin Bias Current
Temperature Coefficient

-- 0.1 -- -- 0.1 --

nA/

Error Comparator

PJ2950A/PJ2951A

PJ2950/PJ2951

Output Leakage Current

=30V --

0.01

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS at V

=15V, Ta=25

, unless otherwise noted.

PJ2950/PJ2951

150mA Low Dropout Voltage Regulators

3-6 2002/01.rev.A

Output Low Voltage

=4.5V, I

=400A -- 150 250 -- 150 250 mV

Upper Threshold Voltage (Note 8)

Power Threshold
Voltage

(Note 8)

-- 75 95 -- 75 95

Hysteresis (Note

Shutdown Input

PJ2950A/PJ2951A

PJ2950/PJ2951

Output Logic Voltage

Low (Regulator ON)
High(Regulator OFF)

2.0

1.3
1.3

0.7

2.0

1.3
1.3

0.7

Shut down Pin Current

Vs =2.4V
Vs = 30V

-- 30

450

600

-- 30

450

600

Regulator Output
Current in Shutdown

(Note 9)

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 T

=25, V

=6V,I

=100A and C

=100F. Additional conditions

for the 8-pin versions are feedback tied to 5V,3V & 3.3V tap output Sense (Vout =5V, 3V & 3.3V) and V

shutdown

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 convered under the specification for thermal regulation.

Note 4: Line regulation for the PJ2951 is tested at 150 for I

=1mA.For I

=100A and Tj=125, 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 100mV below its nominal

value measured at 1V differential at very low value of programmed output voltage , the minimum input supply voltage
of 2V (2.3V over temperature) must be taken in to account .

Note 6: V

ref

out

(Vin-1V),2.3

Vin

30V, 100A

100mA, T

JMAX..

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/1.250=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, 3V & 3.3VTap.

External Capacitors

For the stability of the PJ2950/PJ2951 requires a 1.0 F 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 efficient. For the
operation of below -25 solid tantalum is recommended since the many aluminum type have electrolytes the freeze at about -
30. The ESR of about 5 or less and resonant frequency above 500KHz are most important parameter in the value of
Capacitor. The Capacitors value can be increased without any limit.
At lower values of output current, less output capacitance is required for stability. For the currents below 10 mA the value of
capacitor can be reduce to 0.33F and 0.1F for 1mA. More output capacitance needed for the 8-pin version at voltage below
5V since it runs the error amplifier at lower gain. At worst case 3.3F 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
divider. This feature very important in application like CMOS RAM keep-alive. The PJ2951 output voltage setting with minimum
load of 1 A and external resistors.

APPLICATION HINTS EXTERNAL CAPACITORS

PJ2950/PJ2951

150mA Low Dropout Voltage Regulators

4-6 2002/01.rev.A

If at the input of PJ2950/LP2951 connected to battery or between AC filter capacitor and input is 10 inches wire then 1F
tantalum or aluminum electrolytic capacitor should be connected between input and ground .

Instability can occur if stray capacitor to feedback terminal pin 7 of the PJ2951. This could cues more problem more when using
higher value of external to set the output voltage . To fix this problem the 100 pF capacitor between output and feedback and
increasing output capacitance to 3.3F.

The Compactor produces a logic low output whenever the PJ2951 output falls of regulation by more than around 5% . This is
around 60 mV offset divided by the 1.250 reference voltage. Thus trip remains 5% below nominal regardless of the programmed
output voltage of the regulator . the figure 1 shows the timing diagram depicting the ERROR signal and the regulator output
voltage as the PJ2951 input is ramped up and down . the ERROR 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 on the system requirement 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 400A , this value adds to battery drain in a low better condition,
recommended values 100K to 1M. If the output is unused this resistor is not required.

The PJ2951 output voltage is 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 voltage divider by tying pin 1 to 2 and pin 7 to pin 6.
Refer to Figure 2, there are two external resistor required for this programming. Refer to the below equation for the programming
the output voltage: Volt = V

ref

x (1+R

)+I

The V

ref

is 1.250 and I

is the feedback bias current , nominally -20 nA. The minimum recommended load current of 1A

forces an upper limit of 1.2M on value of R

, If no load presented the I

produces error of typically 2% in Vout which

maybe eliminated at room temperature by trimming R

. To improve the accuracy chooses the value of R2 =100K and this

reduces the error by 0.17% and increases the resistor program current by 12 A . The PJ2951 typically draw 60 A at no load
with pin 2 open-circuit,and this value does not look much .

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 inefficient, as
increasing capacitor from 1F to 220F only decreases the noise from 430V to 160V rms. for a 100KHz bandwidth at 5
volt output. Noise could be also reduce by fourfold by a bypass capacitor across R

since it reduces the high frequency gain from

4 to unity . pick CBYPASS = 1 / 2R1

x 200Hz or choose 0.01 F. When doing this, the output capacitor must be increased to

3.3 F to maintain stability . These changes the output noise from 430V rms . for a 100 kHz bandwidth 5, 3 & 3.3 volt output.
With the bypass capacitor added, noise no longer scales with output voltage so that improvements are more dramatic higher output
voltage .

ERROR DETECTION COMPARATOR OUTPUT

PROGRAMMING THE OUTPUT VOLTAGE OF PJ2951

REDUCING OUTPUT NOISE

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: PJ2950ACT-3.0

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: PJ2950ACT-3.0