Datasheet LP2950CT-5.0, LP2950CT-3.3, LP2950CS-5.0, LP2950CS-3.0, LP2950CS Datasheet (Sipex Corporation)

LP2950/LP2951

100 mA Low Dropout Voltage Regulators

FEATURES APPLICATIONS

• 5.0V, 3.3V and 3.0V Versions @ 100mA Output • Battery Powered Systems

• Very Low Quiescent Current • Cordless Telephones

• Low Dropout Voltage • Radio Control Systems

• Extremely Tight Load and Line Regulation • Portable/Palm Top/Notebook Computers

• Very Low Temperature Coefficient • Portable Consumer Equipment

• Current & Thermal Limiting • Portable Instrumentation

• Need Only 1 µF for Stability

• Offered in TO-263 & SOIC • SMPS Post-Regulator

• Direct Replacement For LP2950/LP2951 Sockets • Voltage Reference

• Automotive Electronics

LP2951 versions only

• Error Flag Warns of Output Dropout

• Logic-Controlled Electronic Shutdown

• Output Programmable From 1.24 to 29V

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 features low quiescent current and very low dropout voltage (Typ. 50mV at light load and 380 mV at 100mA). 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 LP2950/LP2951 useful as a low-power voltage reference.

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 LP2950 is offered in a 3-pin TO-263 package compatible with other 5V, 3.0V & 3.3V regulators. The LP2951 is also available in 8-pin plastic, SO-8 packages.

The regulator output voltage may be pin-strapped for 5.0V, 3.0V or 3.3V or programmed from 1.24V to 29V with an external pair of resistors. Look for SPX2950/51 for 150mA, for SPX2975 for 180mA and SPX2954 for 250mA.

8-Pin Surface Mount (S)

OUTPUT

SENSE

SHUTDOWN

GROUND

1

2

ALPHA AS2930

LP2951

3

4

Top View

8

INPUT

FEEDBACK

7

6

5V or 3.3V TAP

5

ERROR

• Avionics

TO-263-3 (T)

LP2950

1

23

GND

V

IN

Top View

V

OUT

Rev. 11/2/00

LP2950/51

ABSOLUTE MAXIMUM RATINGS

Power Dissipation ..................................Internally Limited Input Supply Voltage ................................................ -0.3V to +30V

Lead Temp. (Soldering, 5 Seconds)......................... 260°C Feedback Input Voltage ............................................ -1.5V to +30V

Storage Temperature Range....................... -65° to +150°C Shutdown Input Voltage............................................ -0.3V to +30V

Operating Junction Temperature Range Error Comparator Output .......................................... -0.3V to +30V

LP2951 ........................................... -55°C to +150°C ESD Rating ...................................................................... 2kV Min

LP2950AC/LP2950C...................... -40°C to +125°C

LP2951AC/LP2951C...................... -40°C to +125°C

ELECTRICAL CHARACTERISTICS

PARAMETER

3 V Versions

Output Voltage T

= 25°C

J

-25°C ≤T

CONDITIONS

(Note 2)

≤85°C

J

at

Full Operating Temperature

Output Voltage

3.3 V Versions

100 µA ≤I T

T

≤

JMAX

J

≤100 mA

L

Output Voltage TJ = 25°C

-25°C ≤T

≤85°C

J

Full Operating Temperature

Output Voltage

5 V Versions

Output Voltage T

100 µA ≤I T

T

≤

JMAX

J

= 25°C

J

-25°C ≤T

≤100 mA

L

≤85°C

J

Full Operating Temperature

Output Voltage

All Voltage Options

100 µA ≤I

T

≤

J

JMAX

≤100 mA

L

Output Voltage Temperature Coefficient (Note 1) Line Regulation (Note

6V ≤Vin ≤30V (Note 4)

3) Load Regulation (Note

3) Dropout Voltage (Note 5)

Ground Current

Current Limit V

100 µA ≤I

I

= 100µ A

L

I

= 100 mA

L

I

= 100 µA

L

I

= 100 mA

L

OUT

100 mA

≤

L

= 0 130 200 130 200 130 200 mA

Thermal Regulation 0.05 0.2 0.05 0.2 0.05 0.2 %/W

Output Noise, 10Hz to 100KHz

= 1µF

C

L

= 200 µF

C

L

= 13.3 µF

C

L

(Bypass = 0.01 µF pins 7 to 1(LP2951))

8-Pin Versions only

Reference Voltage 1.22 1.235 1.25 1.22 1.235 1.25 1.21 1.235 1.26 V

Reference Voltage Over Temperature (Note 6) 1.19 1.27 1.19 1.27 1.185 1.285 V

Feedback Pin Bias

40 60 40 60 40 60 nA

Current

Vs=15V, Ta=25°C, unless otherwise noted.

LP2951

Min. Typ. Max.

2.985

2.964

3.0 3.015

3.036

2.955 3.0 3.045 2.958 3.0 3.042 2.928 3.0 3.072 V

3.284

3.260

3.3 3.317

3.340

3.251 3.3 3.350 3.254 3.3 3.346 3.221 3.3 3.379 V

4.975

4.94

5.0 5.025

5.06

4.925 5.0 5.075 4.93 5.0 5.07 4.88 5.0 5.12 V

20 120 20 120 50 120 ppm/°C

0.03 0.1 0.03 0.1 0.04 0.2 %

0.04 0.1 0.04 0.1 0.1 0.2 %

50

380

80

450

150 8 170

12

430

430 160 100

LP2951

LP2950AC LP2951AC

Min. Typ. Max.

2.985

2.970

2.964

3.284

3.267

3.260

4.975

4.95

4.94

3.0

3.3

5.0

3.015

3.030

3.036

3.317

3.333

3.340

5.025

5.050

5.06

50

380

450

150 8 170

160 100

LP2951AC

LP2950C LP2951C

Min. Typ. Max.

2.970

2.955

2.940

3.267

3.251

3.234

4.95

4.925

4.90

80

3.0

3.3

5.0

50

380

150 8 170

12

430

160 100

LP2951C

3.030

3.045

3.060

3.333

3.350

3.366

5.05

5.075

5.10

80

450

12

UNITS

V

mV mV

A

µ

mA

V rms

µ

V rms

µ

V rms

µ

Rev. 11/2/00

LP2950/51

PARAMETER

8-Pin Versions only (Continued)

Reference Voltage Temperature Coefficient Feedback Pin Bias Current Temperature Coefficient

Error Comparator

Output Leakage Current V

Output Low Voltage VIN = 4.5V

Upper Threshold Voltage Lower Threshold Voltage Hysteresis (Note 8) 15 15 15 mV

Shutdown Input

Input logic Voltage Low (Regulator ON)

Shut down Pin Input Current

Regulator Output Current in Shutdown

Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range.

Note 1:

Unless otherwise specified all limits guaranteed for T

Note 2:

tied to 5V tap and output tied to output sense (V

Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are

Note 3:

covered under the specification for thermal regulation.

: Line regulation for the LP2951 is tested at 150°C for I

Note 4

performance characteristics for line regulation versus temperature and load current.

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

Note 5:

very low values of programmed output voltage, the minimum input supply voltage of 2V ( 2.3V over temperature) must be taken into account.

V

Note 6: Note 7:

≤

REF

OUT

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 = V 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 V is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.

V

Note 8: Note 9:

SHUTDOWN

All typical values are not guaranteed. The value could vary from lot to lot.

BLOCK DIAGRAM

FROM CMO S OR TTL

CONDITIONS

(Note 2)

Min. Typ. Max.

LP2951

LP2950AC LP2951AC

Min. Typ. Max.

LP2950C LP2951C

Min. Typ. Max.

20 20 50 ppm/°C

( Note 7 )

0.1 0.1 0.1 nA/°C

= 30V 0.01 1 0.01 1 0.01 1

OH

150 250 150 250 150 250 mV

= 400µA

I

OL

(Note 8) 40 60 40 60 40 60 mV

(Note 8) 75 95 75 95 75 95 mV

High (Regulator OFF) VS = 2.4V V

= 30V

S

2 30

1.3 0.6 2 1.3 0.7 2 1.3 0.7 V

675

50 800

30

675

50 800

30

675

50 800

(Note 9) 3 10 3 10 3 10

= 25°C, VIN = 6V, IL = 100µA and CL = 1µF. Additional conditions for the 8-pin versions are feedback

≤ (VIN - 1V), 2.3 ≤V

≥ 2V, VIN ≤ 30V, V

UNREGULATED DC

+

SHUTD OW N

= 5V) and V

OUT

30V, 100µA≤I

≤

IN

=0, Feedback pin tied to 5V Tap.

OUT

FEEDB AC K

3

J

SHUTDOWN

= 1mA. For IL = 100 µA and TJ = 125°C, line regulation is guaranteed by design to 0.2%. See typical

L

100 mA, T

≤

L

7

60 mV

+

1.23V

+

REFERENCE

LP2950 and L P2951 Block D iagram

≤ 0.8V.

T

≤

J

JMAX

INP UT

+ _

+

_

.

8

ERROR AM PLIFIE R

ERROR DETECTION COMPARATO R

= (R1 + R2)/R2. For example, at a programmed output

OUT/VREF

1

OUTPUT

180k

Ω

60k

..

Ω

2

SENSE

..

6

5V TA P

5

______

ERROR

4

GROUND

5V @ 100mA

+

µ

TO CMOS OR TTL

MAX

..1F

330k

Ω

UNITS

µ

V

µ µ µ

..

A

A A A

as V

OUT

Rev. 11/2/00

LP2950/51

APPLICATION HINTS EXTERNAL CAPACITORS

The stability of the LP2950/LP2951 requires a 1.0 µF 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 5 Ω or less and resonant frequency above 500 kHz are the most important parameters in the value of the capacitor. The capacitors value may be increased without limit. At lower values of output current, less output capacitance is required for stability. For the currents below 10 mA the value of the capacitor can be reduced to 0.33 µF and 0.1 µF for 1 mA. 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 100 mA load at 1.23V output. 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. 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 100 pF capacitor between

4.75V

OUTPUT

VOLTAGE

_______

ERROR*

INPUT

VOLTAGE 1.3V

* See Application Info.

+

5.0V

_______

+

Figure 1. ERROR Output Timing

output and feedback and increasing the output capacitor to at least 3.3

F.

µ

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 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 V

= 4.75 ).

OUT

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 (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 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:

= V

V

OUT

× (1 + R1/R2)+ IFBR

REF

1

The V

is 1.235 and IFB is the feedback bias current, nominally -20

REF

nA. The minimum recommended load current of 1 µA forces an upper limit of 1.2 MΩ on value of R2. If no load is presented the IFB produces an error of typically 2% in V at room temperature by trimming R

which may be eliminated

OUT

. To improve the accuracy

1

choose the value of R2 = 100k this reduces the error by 0.17% and increases the resistor program current by 12 µA. Since the LP2951 typically draws 60 µA 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 3 lead LP2950 but is relatively inefficient, as increasing the capacitor from 1 µF to 220 µF only decreases the noise from 430 µV to 160 µV Noise could also be reduced fourfold by a bypass capacitor across R

for a 100 kHz bandwidth at 5V output.

RMS

1

since it reduces the high frequency gain from 4 to unity. Pick

C

BYPASS

1 / 2πR

≅

× 200 Hz

1

or choose 0.01 µF. When doing this, the output capacitor must be increased to 3.3 µF to maintain stability. These changes reduce the output noise from 430 µV to 100 µV

for a 100 kHz bandwidth at

RMS

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. 11/2/00

,

LP2950/ LP2951

TYPICAL PERFORMANCE CHARACTERISTIC

OUTPUT VOLTAGE (VOLTS)

OUTPUT VOLTAGE (V)

GROUND CURRENT (mA)

DROP-OUT VOLTAGE (mV)

DROPOUT CHARACTERISTICS

6

5

4

3

2

1

0

5.06

5.04

5.02

5.0

4.98

4.96

4.94

-75

16

12

8

4

-75

600

500

400

300

100

50

0

-75

RL=50k

123 456

0

INPUT VOLTAGE (VOLTS)

OUTPUT VOLTAGE VS. TEMP OF 3

REPRESENTATIVE UNITS

-25 0 25 50 75 100 125 150

-50

TEMPERATURE (ºC)

GROUND CURRENT

-25 0 25 50 75 100 125 150

-50

TEMPERATURE (ºC)

DROP-OUT VOLTAGE

~ ~

-25 0 25 50 75 100 125 150

-50

TEMPERATURE (ºC)

Ω

VIN = 6V

I

= 100mA

L

RL=50k

0.2%

Ω

IL = 100mA

IL = 100µA

250

225

200

175

150

125

100

75

INPUT CURRENT (µA)

50

25

0

320

280

240

200

160

120

80

GROUND CURRENT (µA)

40

0

16

14

12

10

8

6

GROUND CURRENT

4

2

0

500

400

300

200

DROP-OUT VOLTAGE (mV)

100

0

INPUT CURRENT

RL = 50k

Ω

8

RL =

123

INPUT VOLTAGE (VOLTS)

GROUND CURRENT

12345678

INPUT VOLTAGE (VOLTS)

GROUND CURRENT

2345678

1

INPUT VOLTAGE

DROP-OUT VOLTAGE

TJ = 25ºC

1mA100µA

OUTPUT CURRENT

10 150

IL= 1mA

IL= 0

IL=100mA

10mA

100mA

10

1

0.1

GROUND PIN CURRENT (mA)

0.01

160 150 140 130 120 110 100

90 80 70 60 50

INPUT CURRENT (mA)

40 30 20 10

0

240

220

200

QUIESCENT CURRENT (µA)

180

170

160

150

140

130

120

SHORT CIRCUIT CURRENT (mA)

110

QUIESCENT CURRENT

0.1 1 10 150

-75

LOAD CURRENT (mA)

INPUT CURRENT

12345678910

0

INPUT VOLTAGE (VOLTS)

QUIESCENT CURRENT

VIN=6V

I

=100mA

L

-25 0 25 50 75 100 125 150

-50

TEMPERATURE (ºC)

SHORT CIRCUIT CURRENT

-75

-25 0 25 50 75 100 125 150

-50

TEMPERATURE (ºC)

RL=50

Ω

Rev. 11/2/00

LP2950/LP2951

TYPICAL PERFORMANCE CHARACTERISTICS

COMPARATOR OUTPUT (V)

OUTPUT IMPEDANCE (OHMS)

ERROR COMPARATOR OUTPUT

8

V

= 5V

6

4

2

0

-2

0

10

IO = 100µA

5

2

1

0.5

0.2

0.1

0.05

0.02

0.01 10 100 1K 10K 100K 1M

LP2951

MINIMUM OPERATING VOLTAGE

10

OUT

HYSTERESIS

PULLUP RESISTOR TO SEPARATE 5V SUPPLY

12345

INPUT VOLTAGE (V)

OUTPUT IMPEDANCE

IO = 1mA

IO = 100mA

V

= 5V

OUT

C

= 1µF

L

FREQUENCY (Hz)

SINK CURRENT (mA)

RIPPLE REJECTION (dB)

LP2951

COMPARATOR SINK CURRENT

2.5

2.0

1.5

1.0

0.5

0.0

0.1

OUTPUT LOW VOLTAGE (V)

90

80

70

60

50

40

CL = 1µF

VIN = 6V

30

V

OUT

20

1

10

20

1

10

0

0.1

MINIMUM OPERATING VOLTAGE (V)

0.01

-75 0 75 150

-50 -25 25 50 100 125 -25 25 125 0 0.5

TEMPERATURE

LOAD TRANSIENT RESPONSE

250

200

150

100

50

0

-50

-100

~ ~

CURRENT CHANGE (mV)

100

LOAD OUTPUT VOLTAGE

mA

100

µA

012345

TIME (ms)

CL = 1µF

V

OUT

= 5V

-10

BIAS CURRENT (nA)

-20

-30

-75

-50 0 50 75 100 150

80

60

40

20

0

-20

-40

-60

~ ~

CURRENT CHANGE (mV)

LOAD OUTPUT VOLTAGE

100

µA

100

µA

048121620

(continued)

TA = 125ºC

TA = 25ºC

TA = -55ºC

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

RIPPLE REJECTION

IL = 0

IL = 100µA

= 5V

10210310410510

FREQUENCY (Hz)

LP2951

FEEDBACK BIAS CURRENT

TEMPEATURE (ºC)

LOAD TRANSIENT RESPONSE

CL = 1µF

V

= 5V

OUT

TIME (ms)

LINE TRANSIENT RESPONSE

100 mV

50

mV

0

-50 mV

~ ~

8V

VOLTAGE CHANGE

INPUT OUTPUT VOLTAGE

6V

4V

0 200

90

80

70

60

50

40

RIPPLE REJECTION (dB)

30

6

20

50

0

-50

-100

-150

FEEDBACK CURRENT (µA)

-200

-250

-2.0

7

6

5

4

3

2

1

0

SHUTDOWN OUTPUT

2

PINOUT VOLTAGE (V) VOLTAGE (V)

0

-2

RIPPLE REJECTION

IL = 10mA

2

1

10

-1000100 200 300 400 500 600 700

FREQUENCY (Hz)

LP2951 FEEDBACK PIN CURRENT

PIN 7 DRIVEN BY EXTERNAL SOURCE (REGULATOR RUN

OPEN LOOP)

TA =1 25ºC

TA = 55ºC

-1.5 -1.0

FEEDBACK VOLTAGE (V)

ENABLE TRANSIENT

CL = 1µF IL = 1mA

V

= 5V

OUT

600 800

400

TIME(µs)

CL= 1µF VIN = 6V

V

OUT

IL = 10mA

3

10410

10

TA = 25ºC

-0.5 1.0

IL = 10mA

VIN = 8V

CL = 10µF V

OUT

TIME

= 5V

5

6

10

Rev. 11/2/00

TYPICAL PERFORMANCE CHARACTERISTICS

LP2950 MAXIUM RATED OUTPUT

120

TO-92 PACKAGE

TA = 85 ºC

INPUT VOLTAGE (V)

TEMPERATURE (ºC)

0.25" LEADS SOLDERED

TO PC BOARD

T

= 125 ºC

JMAX

TA=25 ºC

100

80

60

40

OUTPUT CURRENT (mA)

20

0

010 20 30

SHUTDOWN THRESHOLD VOLTAGE

1.8

1.6

1.4

1.2

1.0

0.8

SHUTDOWN THRESHOLD VOLTAGE (V)

0.6

-50 -25 0 25 50 75 100 125 150

-75

LP2951 DIVIDER RESISTANCE

400

Ω)

Ω)Ω)

Ω)

300

200

100

PIN 2 TO PIN 4 RESISTANCE (k

0

-50 -25 25 50 100 125

25155

-75 0 75 150

TEMPERATURE (ºC)

THERMAL RESPONSE

5

4

2

0

-2 ~

~

1

POWER OUTPUT VOLTAGE

0

DISSIPATION (W) CHANGE (mV)

-1

10 20 30 40 50

0

TIME (µs)

30

25

20

15

10

5

0

~ ~

10

5

0

OUTPUT VOLTAGE CHANGE (mV)

-5

-10

5

LINE REGULATION

IL = 100µA

TJ = 150 ºC

TJ = 125 ºC IL = 100µA

10 15 20 25 30

INPUT VOLTAGE (V)

IL = 1mA

(continued)

1.25W

80

70

60

50

40

30

RIPPLE REJECTION (dB)

20

10

1

10

RIPPLE REJECTION

IL = 50µA

IL = 100mA

CL = 1µF

VIN = 6V

V

= 5V

OUT

2

10

OUTPUT CURRENT (mA)

VOLTAGE NOISE

SPECTRAL DENSITY (µV/Hz)

10310

FREQUENCY (Hz)

LP2950/LP2951

LP2950 MAXIUM RATED OUTPUT

120

100

80

60

40

20

0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

10

4

CURRENT

TA = 50ºC

TA = 85ºC

510 15 20 2530

INPUT VOLTAGE (V)

OUTPUT NOISE

CL = 220µF

CL = 3.3µF

2

3

10

FREQUENCY (Hz)

6

5

10

8-PIN

MOLDED

DIP SOLDERED

TO PC BOARD

T

= 125º C

JMAX

V

= 5V

OUT

TA = 25ºC

IL = 100mA

CL = 1µF

4

10

5

10

Rev. 11/2/00

LP2950/LP2951

TYPICAL APPLICATIONS

+V

GND

+V

LP2951

4

IN

8

IN

V

OUT

FB

7

1.23V

V

REF

1.2 to30V

1

R

ERROR

OUTPUT

SHUTDOWN

INPUT

*MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 4mV TO 400mV. DEPENDING ON LOAD CURRENT. CURRENT LIMIT IS TYPICALLY 160mA

+

1

2

.01uF

3.3uF

5

3

______ ERROR

SD

GND

+V

IN

8

+V

IN

LP2951

4

1

V

OUT

*V

FB

7

Fig.3 Wide Input Voltage Range Current Limiter

OUT

= V

IN

ERROR

OUTPUT

100K

5

______ ERROR

SHUTDOWN

INPUT

3

SD

Figure 1. Adjustable Regulator

+V

IN

470K

Ω

..

470K

______

5

ERROR

Ω

..

3

SD

8

+V

IN

LP2951

GND

4

1

V

OUT

V

OUT

+

1uF

FB

R

1

7

R

2

Fig.2 Latch Off When Error Flag Occurs

Rev. 11/2/00

TYPICAL APPLICATIONS

+

6V SEALED LEADACID BATTE RY SOURCE

120K

FB

FOR 5.5 V

400K

Ω

39k

..

-

C4

+

1%

6V LEADACID BATTE RY

1%

R

1%

(continued)

1.5K

Ω

..

Ω

RESET

3

AS385

..

100K

Ω

______

5

ERROR

3

SD

Ω

39k

..

100k

Ω

..

Ω

..

1k

Ω

..

10k

Ω

..

Ω

20k

..

Fig. 5 Regulator with State-of-Charge Indicator

Ω

..

1N457

3

..

SD

Fig.4 Low Battery Disconnect

8

+V

IN

LP2951

GND

4

C1

+

-

C2

+

-

C3

+

* OPTIONAL LATCH OFF WHEN DROPOUT OCCURS. ADJUST R3 FOR C2 SWITCHING WHEN V * OUTPUTS GO LOW WHEN V

100k

IS 6.0V

IN

SENSE

TAP

Ω

2

V

OUT

FB

+V

1

7

6

..

<5.8V**

Ω

..

<6.0V**

Ω

..

<6.2V**

8

+V

IN

LP2951

GND

4

V

OUT

SENSE

1

+

2

1uF

= 5V

OUT

+

1uF

DROPS BELOW DESGNATED THRESHHOLDS

IN

LP2950/LP2951

MAIN V-

MEMORY V+

20K

NI-CAD BACKUP BATTE RY

Ω

..

Rev. 11/2/00

TYPICAL APPLICATIONS

(continued)

+V

AUX SH UTDOW INPUT

ON

OFF

3

SD

+V

LP2951

GND

TEMP SENSOR

+

AS35

-

4

Fig 6. System Over Temperature Protection

4

20mA

1N4001

0.1uF

8

+V

IN

LP2951

GND

4

1

V

OUT

7

FB

1N457

4.7mA

2

360K

+5V

Ω

Open Circuit Detector for 4mA to 20mA Current Loop

Fig. 7

MIN VOLTAGE = 4V

IN

8

IN

OUTPUT

..

_______

ERROR

V

OUT

FB

7

8.2K

10K

Ω

5

1

Ω

..

5 DEGREE SHUTDOWN FLAG

..

EXTERNAL CIRCUIT PROTECTED FROM OVER TEMPERATURE (V+ GOES OFF WHEN TEMP > 125)

UNREGULATED INPUT

LP2950/LP2951

5

IN

LP2951

3

V

TAP

FB

7

Fig 8. 300 mA Regulator with 0.75V

OR

RELAY

330K

27K

Ω

..

+

4.7uF

GND

V

SENSE

4

OUT

1

2

..

5V

OUTPUT

LOAD 50mA TO 300 mA

2N5432

Rev. 11/2/00

SCHEMATIC DIAGRAM

LP2950/LP2951

Rev. 11/2/00

LP2950/LP2951

ORDERING INFORMATION

Ordering No. Precision Output Voltage Packages

LP2950AS LP2950AS-3.0 LP2950AS-3.3 LP2950AS-5.0 LP2950CS LP2950CS-3.0 LP2950CS-3.3 LP2950CS-5.0 LP2950AT LP2950AT-3.0 LP2950AT-3.3 LP2950AT-5.0 LP2950CT LP2950CT-3.0 LP2950CT-3.3 LP2950CT-5.0

1% Adj 8 Lead SOIC 1% 3.0V 8 Lead SOIC 1% 3.3V 8 Lead SOIC 1% 5.0V 8 Lead SOIC

0.5% Adj 8 Lead SOIC

0.5% 3.0V 8 Lead SOIC

0.5% 3.3V 8 Lead SOIC

0.5% 5.0V 8 Lead SOIC 1% Adj 3 Lead TO-263 1% 3.0V 3 Lead TO-263 1% 3.3V 3 Lead TO-263 1% 5.0V 3 Lead TO-263

0.5% Adj 3 Lead TO-263

0.5% 3.0V 3 Lead TO-263

0.5% 3.3V 3 Lead TO-263

0.5% 5.0V 3 Lead TO-263

SIGNAL PROCESSING EXCELLENCE

Corporation

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. 11/2/00