Datasheet LP2960IN-3.3, LP2960IMX-5.0, LP2960IMX-3.3, LP2960IM-5.0, LP2960IM-3.3 Datasheet (NSC)

LP2960
Adjustable Micropower 0.5A Low-Dropout Regulators

General Description

The LP2960 is a micropower voltage regulator with very low
dropout voltage (12 mV typical at 1 mA load and 470 mV
typical at 500 mA load) and very low quiescent current
(450 µA typical at 1 mA load).

The LP2960 is ideally suited for battery-powered systems:
the quiescent current increases only slightly at dropout,
which prolongs battery life.

The LP2960 retains all the desirable characteristics of the
LP2953, and offers increased output current.

The error flag goes low anytimetheoutput drops more than
5%out of regulation.

Reverse battery protection is provided.
The LP2960 requires only 10 µF of output capacitance for

stability (5V version).
The internal voltage reference is made available for external

use, providing a low-T.C. reference with very good regulation
characteristics.

The parts are available in 16-pin plastic DIP and 16-pin sur­face mount packages.

Features

n Output voltage adjusts from 1.23V–29V
n Guaranteed 500 mA output current
n 5V and 3.3V versions available
n 16-pin DIP and 16-pin SO packages
n Low dropout voltage
n Low quiescent current
n Tight line and load regulation
n Low temperature coefficient
n Current limiting and thermal protection
n Logic-level shutdown
n Can be wired for snap-ON and snap-OFF
n Reverse battery protection

Applications

n High-efficiency linear regulator
n Regulator with under-voltage shutdown
n Low dropout battery-powered regulator
n Cellular telephones

Block Diagram

DS011962-1

April 1999

LP2960 Adjustable Micropower 0.5A Low-Dropout Regulators

© 1999 National Semiconductor Corporation DS011962 www.national.com

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Storage Temperature Range −65˚C to +150˚C
Operating Junction Temperature

Range
LP2960AI/LP2960I −40˚C to +125˚C

Lead Temperature (Soldering, 5 sec.) 260˚C
Power Dissipation (Note 2) Internally Limited
Input Supply Voltage −20V to +30V
Feedback Input Voltage (Note 3) −0.3V to +5V
Comparator Input Voltage (Note 4) −0.3V to +30V
Comparator Output Voltage (Note 4) −0.3V to +30V
ESD Rating (Note 15) 1.5 kV

Electrical Characteristics Limits in standard typeface are for T

J

=

25˚C, and limits in boldface type apply

over the full operating temperature range. Unless otherwise specified: C

IN

=

4.7 µF, V

IN

=

V

O

(NOM) + 1V, I

L

=

1 mA,

C

OUT

=

10 µF for 5V parts or C

OUT

=

22 µF for 3.3V parts, Feedback pin is tied to V

TAP

pin, Output pin is tied to Sense pin,

V

S/D

=

2V.

Symbol Parameter Conditions Typ

LP2960AI

(Note 14)

LP2960I

(Note 14)

Units

Min Max Min Max

V

O

Output Voltage
(5V Versions)

1mA≤IL≤500 mA

5.0

4.962

4.930

5.038

5.070

4.925

4.880

5.075

5.120

V

Output Voltage
(3.3 Versions)

1mA≤I

L

≤500 mA

3.3

3.275

3.254

3.325

3.346

3.250

3.221

3.350

3.379

Output Voltage
Temperature Coefficient

(Note 5)

20 130 160 ppm/˚C

Output Voltage
Line Regulation

V

IN

=

[V

O

(NOM) + 1V] to 30V

0.06

0.2

0.5

0.4

0.8

%

Output Voltage
Load Regulation

(Note 6)

0.08

0.16

0.30

0.20

0.40

%

V

IN−VO

Dropout Voltage (Note 7) I

L

=

1mA

12

30

50

30

50

mV

I

L

=

100 mA

180

250

350

250

350

I

L

=

200 mA

260

350

450

350

450

I

L

=

500 mA

470

600

800

600

800

I

GND

Ground Pin Current
(Note 8)

I

L

=

1mA

450

600

750

600

750

µA

I

L

=

100 mA

2.6

4.0

5.0

4.0

5.0

mA

I

L

=

200 mA

2.5

8

10

8

10

I

L

=

500 mA

21

35

40

35

40

I

GND

Ground Pin Current
at Dropout (Note 8)

V

IN

=

V

O

(NOM) − 0.5V

I

L

=

100 µA

1.8

3

5

3

5

mA

Ground Pin Current
at Shutdown (Note 8)

V

SD

≤ 1.1V

300 400 400 µA

I

LIMIT

Current Limit R

L

=

0.5Ω
1000

1500

1600

1500

1600

mA

Thermal Regulation (Note 10)

0.05 0.2 0.2

%

/W

e

n

Output Noise Voltage

@

I

L

=

100 mA

(10 Hz–100kHz)

C

OUT

=

10 µF 300

µV RMSC

OUT

=

47 µF 210

C

OUT

=

47 µF (Note 11) 130

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Electrical Characteristics Limits in standard typeface are for T

J

=

25˚C, and limits in boldface type apply

over the full operating temperature range. Unless otherwise specified: C

IN

=

4.7 µF, V

IN

=

V

O

(NOM) + 1V, I

L

=

1 mA,

C

OUT

=

10 µF for 5V parts or C

OUT

=

22 µF for 3.3V parts, Feedback pin is tied to V

TAP

pin, Output pin is tied to Sense pin,

V

S/D

=

2V. (Continued)

Symbol Parameter Conditions Typ

LP2960AI

(Note 14)

LP2960I

(Note 14)

Units

Min Max Min Max

V

REF

Reference Voltage

1.235

1.220

1.210

1.250

1.265

1.210

1.195

1.260

1.275

V

Reference Voltage
Line Regulation

(Note 13)

0.05

0.1

0.30

0.2

0.4

%

Reference Voltage
Load Regulation

I

REF

=

0–200 µA

0.45

0.6

0.9

1.2

1.5

%

Reference Voltage
Temperature Coefficient

(Note 5)

20 ppm/˚C

I

B

(FB) Feedback Pin Bias

Current

−20

−50

−70

−50

−70

nA

DROPOUT DETECTION COMPARATOR

I

OH

Output HIGH Leakage V

OH

=

30V

0.01

1

2

1

2

µA

V

OL

Output LOW Voltage V

IN

=

V

O

(NOM) − 1V

I

O

(COMP)=400 µA

125

250

400

250

400

mV

V

THR

(max) Upper Threshold Voltage (Note 9)

−60

−80

−100

−35

−25

−80

−100

−35

−25

mV

V

THR

(min) Lower Threshold Voltage (Note 9)

−85

−130

−200

−70

−35

−130

−200

−70

−35

mV

HYST Hysteresis (Note 9) 25 mV

SHUTDOWN INPUT

V

OS

Input Offset Voltage (Referred to V

REF

)

±

5

−18

−24

18

24

−18

−24

18

24

mV

HYST Hysteresis (Referred to V

REF

)10 mV

I

B

Input Bias Current V

S/D

=

0–5V

−20

−60

−10060100

−60

−10060100

nA

I

OUT

(S/D) Regulator Output Current

in Shutdown

(Note 12)

3

12

20

12

20

µA

AUXILIARY COMPARATOR

V

OS

Input Offset Voltage (Referred to V

REF

)

±

5

−15

−20

15

20

−15

−20

15

20

mV

HYST Hysteresis (Referred to V

REF

)10 mV

I

B

Input Bias Current V

COMP

=

0–5V

−20

−60

−10060100

−60

−10060100

nA

I

OH

Output HIGH Leakage V

OH

=

30V

V

COMP

=

1.3V

0.01

1

2

1

2

µA

V

OL

Output LOW Voltage V

COMP

=

1.1V

I

O

=

400 µA

125

250

400

250

400

mV

Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the de­vice outside of its rated operating conditions.

Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, T

J

(max), the junction-to-ambient thermal resistance, θ

J−A

,

and the ambient temperature, T

A

. The maximum allowable power dissipation at any ambient temperature is calculated using:

Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. See APPLICATION
HINTS for additional information on heatsinking and thermal resistance.

Note 3: When used in dual-supply systems where the regulator load is returned to a negative supply, the output voltage must be diode-clamped to ground.

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Electrical Characteristics Limits in standard typeface are for T

J

=

25˚C, and limits in boldface type apply

over the full operating temperature range. Unless otherwise specified: C

IN

=

4.7 µF, V

IN

=

V

O

(NOM) + 1V, I

L

=

1 mA,

C

OUT

=

10 µF for 5V parts or C

OUT

=

22 µF for 3.3V parts, Feedback pin is tied to V

TAP

pin, Output pin is tied to Sense pin,

V

S/D

=

2V. (Continued)

Note 4: May exceed the input supply voltage.
Note 5: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 6: Output voltage load regulation is measured at constant junction temperature using low duty cycle pulse testing. Two separate tests are performed, one for

the load current range of 100 µA to 1 mA and one for the 1 mA to 500 mA range. Changes in output voltage due to heating effects are covered by the thermal regu­lation specification.

Note 7: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below the value measured with a 1V differential. At
very low values of programmed output voltage, the input voltage minimum of 2V (2.3V over temperature) must be observed.

Note 8: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the ground pin current, output load current, and
current through the external resistive divider (if used).

Note 9: Dropout detection comparator threshold voltages are expressed in terms of a voltage differential measured at the Feedback terminal below the

nominal

ref-

erence voltage, which is the reference voltage measured with V

IN

=

V

O

(NOM) + 1V.To express these thresholds in terms of output voltage change, multiply by the

error amplifier gain which is V

O/VREF

=

(R1 + R2)/R2 (see

Basic Application Circuit

).

Note 10: Thermal regulation is the change in output voltage at a time T after a change in power dissipation, excluding load or line regulation effects. Specifications
are for a 400 mA load pulse at V

IN

=

V

O

(NOM) + 15V (6W pulse) for T=10 ms.

Note 11: Connect a 0.1 µF capacitor from the output to the feedback pin.
Note 12: Vshutdown ≤ 1.1V, V

IN

<

30V, V

OUT

=

0V.

Note 13: Two separate tests are performed for referenc e voltage line regulation, one covering 2.5V ≤ V

IN

≤ VO(NOM) + 1V and the other test for VO(NOM) + 1V

≤ V

IN

≤ 30V.

Note 14: All room temperature limits are 100%production tested.Alllimitsattemperature extremes are guaranteed via correlation using standard Statistical Quality
Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level.

Note 15: Human Body Model, 200 pF discharged through 1.5 kΩ.

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Basic Application Circuit

Connection Diagrams and Ordering Information

DS011962-2

16-Pin Surface Mount Package

DS011962-3

Top View

Order Number LP2960IM-5.0, LP2960AIM-5.0,

LP2960IM-3.3 or LP2960AIM-3.3
See NS Package Number M16A

16-Pin DIP Package

DS011962-4

Top View

Order Number LP2960IN-5.0, LP2960AIN-5.0,

LP2960IN-3.3 or LP2960AIN-3.3

See NS Package Number N16G

*

Internally Connected to Power Ground

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Typical Performance Characteristics Unless otherwise specified: C

IN

=

4.7 µF, V

IN

=

6V, I

L

=

1 mA,

C

OUT

=

10 µF, Feedback pin is tied to V

TAP

pin, Output pin is tied to Sense pin, V

S/D

=

2V, V

OUT

=

5V.

Ground Pin Current

DS011962-5

Ground Pin Current

DS011962-6

Ground Pin Current

DS011962-7

Ground Pin Current

DS011962-8

Ground Pin Current

DS011962-9

Dropout Characteristics

DS011962-10

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Typical Performance Characteristics Unless otherwise specified: C

IN

=

4.7 µF, V

IN

=

6V, I

L

=

1 mA,

C

OUT

=

10 µF, Feedback pin is tied to V

TAP

pin, Output pin is tied to Sense pin, V

S/D

=

2V, V

OUT

=

5V. (Continued)

Dropout Voltage vs Temperature

DS011962-11

Dropout Voltage vs Load Current

DS011962-12

Enable Transient

DS011962-13

Enable Transient

DS011962-14

Load Transient

DS011962-15

Load Transient

DS011962-16

www.national.com7

Typical Performance Characteristics Unless otherwise specified: C

IN

=

4.7 µF, V

IN

=

6V, I

L

=

1 mA,

C

OUT

=

10 µF, Feedback pin is tied to V

TAP

pin, Output pin is tied to Sense pin, V

S/D

=

2V, V

OUT

=

5V. (Continued)

Current Limit vs Temperature

DS011962-17

Line Transient Response

DS011962-18

Line Transient Response

DS011962-19

Ripple Rejection

DS011962-20

Ripple Rejection

DS011962-21

Thermal Regulation

DS011962-22

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Typical Performance Characteristics Unless otherwise specified: C

IN

=

4.7 µF, V

IN

=

6V, I

L

=

1 mA,

C

OUT

=

10 µF, Feedback pin is tied to V

TAP

pin, Output pin is tied to Sense pin, V

S/D

=

2V, V

OUT

=

5V. (Continued)

Output Impedance

DS011962-23

Output Noise Voltage

DS011962-24

Feedback Bias Current

DS011962-25

Divider Resistance

DS011962-26

Error Output Voltage vs Input Voltage

DS011962-27

Dropout Detection Comparator
Threshold Voltage

DS011962-28

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Schematic Diagram

DS011962-38

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Application Hints

EXTERNAL CAPACITORS

Bypass capacitors on the input and output of the LP2960 are
required: without these capacitors,

the part will oscillate

.

A capacitor (whose value is

at least

4.7 µF) must be con-

nected from the V

IN

pin to ground. If the input capacitor is lo­cated more than one inch away from the LP2960, the capaci­tor may have to be increased to 22 µF to assure stability. A
capacitor is also required between V

OUT

and Ground, and
the minimum amount of capacitance required here depends
on output voltage.

If the output voltage of the LP2960 is set to 5V,a minimum of
10 µF is needed in output capacitance. At 3.3V output, at
least 22 µF is required to assure stability.

ESR LIMIT: The ESR of the capacitor used on the LP2960
must be less than 0.7Ω

throughout the entire operating tem-

perature range

to assure stability.

The ESR of an aluminum eIectroIytic capacitor is typically
only specified at 25˚C, and does not reflect the maximum
ESR that can be expected to occur over the entire tempera­ture range of the capacitor.

Aluminum electrolytics show a marked increase in ESR at
low temperatures (ESR can increase by a factor of 30 or
more when going from 25˚C to −30˚C) which could lead to
oscillation probIems in applications with very low ambient
temperatures. Solid tantalum capacitors are recommended
for use in such cases.

Regulator instability can be caused by stray (board layout)
capacitance appearing at the Feedback terminal. Oscilla­tions from this effect are most Iikely to occur when very high
value resistors are used to set the output voltage.

Adding a 100 pF capacitor between the Output and Feed­back pins and increasing the output capacitor to at least
22 µF will stop the osciIIations.

MINIMUM LOAD

The internal resistive divider in the LP2960 provides suffi­cient output loading for proper regulation. If externaI resis­tors are used to set the LP2960 output voltage, a minimum
current of 5 µA through the externaI resistive divider is rec­ommended.

It should be noted that a minimum load current is specified in
several of the test conditions listed under

Electrical Charac-

teristics,

and this value of load current must be used to get

correlation on these test limits.

PROGRAMMING THE OUTPUT VOLTAGE

The LP2960 regulator may be pin-strapped for operation at
the nominal output voltage using its internal resistive divider
by tying the Output and Sense pins together and also tying
the Feedback and V

TAP

pins together.

Alternatively,it may be programmed for any voltage between
the 1.23V reference and the 30V maximum rating using an
external pair of resistors (see Basic Application Circuit).

The complete equation for the output voltage is:

V

OUT

=

V

REF

x (1 + R1/R2) + (IFBx R1)

The term V

REF

is the 1 .23V reference and IFBis the Feed­back pin bias current (−20 nA typical). The minimum recom­mended load current of 5 µAsets an upper limit of 240 kΩ on
the value of R2 in cases where the regulator must work with
no load (see

Minimum Load

).

For best output accuracy, choosing R2=100 kΩ will reduce
the error resulting from I

FB

to 0.17%while increasing the re-

sistive divider current to 12 µA. Since the typicaI quiescent
current of the LP2960 is 450 µA, this added current through
R2 is negligible.

DROPOUT VOLTAGE

The dropout voltage of the regulator is defined as the mini­mum input-to-output voltage differential required for the out­put voltage to stay within 100 mV of the output voltage mea­sured with a 1V differential. The dropout voltage is
independent of the programmed output voltage.

OUTPUT ISOLATION

If the LP2960 output is connected to an active voltage
source (such as a battery) the regulator input should not be
shorted to ground, as this will cause a large current to flow
from the battery into the LP2960 output lead.

If the LP2960 input is

left floating

with the output connected
to a battery,a small current (a few mA) will flow into the out­put lead.

The “reverse” current flowing from the battery into the
LP2960 output can be prevented by using a blocking diode
between the output and the battery.

REDUCING OUTPUT NOISE

In reference applications it may be desirabIe to reduce the
AC noise present on the output. One method is to reduce
regulator bandwidth by increasing output capacitance. This
is relatively inefficient, since large increases in capacitance
are required to get significant improvement.

Noise can be reduced more effectively by a bypass capacitor
placed across R1 (refer to

Basic Application Circuit

).

A 0.1 µF capacitor connected across R1 will reduce the high
frequency gain of the circuit to unity, lowering the RMS out­put noise voltage from 210 µV to 130 µV (typical) using a 10
Hz–100 kHz bandwidth test measurement.

Also, output noise is no longer proportional to the output volt­age, so improvements are more pronounced at higher output
voltages.

IMPORTANT: Since the 0.1 µF capacitor reduces the AC
gain of the LP2960 to unity, the output capacitance must be
increased to at least 33 µF to assure regulator stability.

DROPOUT DETECTION COMPARATOR

The dropout detection comparator produces a logic “LOW”
on the Error output whenever the LP2960 output drops out of
regulation by more than about 5%. This figure results from
the comparator’s built-in offset of 60 mV divided by the 1.23V
reference (refer to block diagram).

The “5%below nominal” trip level remains constant regard­less of the programmed output voltage. An out-of-regulation
condition can result from low input voltage, current limiting,
or thermal limiting.

The figure below gives a timing diagram showing the rela­tionship between the output voltage, the Error output, and in­put voltage as the input voltage is ramped up and down to a
regulator programmed for 5V output.

www.national.com11

Application Hints (Continued)

The Error signal becomes low as V

IN

exceeds about 1.3V.It
goes high at about 5V input, where the output equals 4.75V.
Since the dropout voltage is load dependent, the

input volt-

age

trip points will vary with load current, but the

output volt-

age

trip point does not.

The comparator has an open-collector output which requires
an external pull-up resistor. This resistor may be connected
to the LP2960 output or another supply voltage.

Best operation is obtained by connecting the pull-up to the
LP2960 output. If the pull-up resistor is connected to an ex­ternal 5V supply, the error flag will incorrectly signal “HIGH”
whenever V

IN

<

1.3V (see

Error Output Timing Diagram

).

In selecting a value for the pull-up resistor, note that while
the output can sink 400 µA, this current adds to battery drain.
Suggested values range from 100 kΩ–1 MΩ. The resistor is
not required if the output is unused.

If a large output capacitance is used, a false logic “HIGH”
can be generated when V

IN

≈1.3V.In this case, the error out­put becomes a high impedance, causing the voltage at the
error output to rise to its pull-up value. If the pull-up resistor
is connected to V

OUT

, the error output can rise to 1.2V

(which is a logic “HIGH” signal

incorrectly

signifying the out-

put is in regulation).
The user may wish to divide down the error flag voltage us-

ing equal-value resistors (10 kΩ suggested) to ensure a
low-level logic signal during any fault condition, while still al­lowing a valid high logic level during normal operation.

AUXILIARY COMPARATOR

The LP2960 contains an auxiliary comparator whose invert­ing input is connected to the 1.23V reference. The auxiIiary
comparator has an open-collector output whose electrical
characteristics are similar to the dropout detection compara­tor. The non-inverting input and output are brought out for
external connections.

SHUTDOWN INPUT

A logic-level signal will shut off the regulator output when a
“LOW” (

<

1.2V) is applied to the Shutdown input.

To prevent possible mis-operation, the Shutdown input must
be actively terminated. If the input is driven from

open-collector logic, a pull-up resistor (20 kΩ–100 kΩ rec­ommended) should be connected from the Shutdown input
to the regulator input.

If the Shutdown input is driven from a source which actively
pulls low and high (like an op-amp), the puIl-up resistor is not
required, but may be used.

If the Shutdown input is to be unused, the cost of the pull-up
resistor can be saved by tying the Shutdown input directly to
the regulator input.

IMPORTANT: Since the Absolute Maximum Ratings state
that the Shutdown input can not go more than 0.3V below
ground, the reverse-battery protection feature which protects
the regulator input is sacrificed if the Shutdown input is tied
directly to the regulator input.

If reverse-battery protection is required in an application,

the
pull-up resistor between the Shutdown input and the regula­tor input must be used

.

GROUND CONNECTIONS

The pins designated GND (see

Connection Diagrams

) must

be connected to the high-current ground point in the circuit.
The GND pins are electrically connected (through the lead

frame) to the die substrate, making them ideal for conducting
ground current or heat (see

Heatsinking

).

The parts in the surface-mount (M) package also have an
Analog Ground pin, which is the ground point on the die for
the regulator reference circuitry.

Along with the Sense pin, the availability of the Analog
Ground pin allows the designer the ability to use “remote”
sensing and eliminate output voltage errors due to IR drops
occurring along PC board traces.

IMPORTANT: The Analog Ground pin must be connected to
circuit ground at some point for the regulator to operate.

If remote sensing is not needed, the Analog Ground pin can
simply be pin-strapped to the adjacent GND pin.

HEATSINKING

A heatsink may be required with the LP2960 depending on
the maximum power dissipation and maximum ambient tem­perature of the application. Under alI possible operating con­ditions, the junction temperature must be within the range
specified under Absolute Maximum Ratings.

To determine if a heatsink is required, the power dissipated
by the regulator, P

D

, must be calculated.

The figure below shows the voltages and currents which are
present in the circuit, as welI as the formula for calcuIating
the power dissipated in the regulator:

Error Output Timing Diagram

DS011962-29

*

In shutdown mode, ERROR will go high if it has been pulled up to an

external supply. To avoid this invalid response, pull-up to regulator output.

**

Exact value depends on dropout voltage. (See Application Hints)

Power Dissipation Diagram

DS011962-30

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Application Hints (Continued)

The next parameter which must be calculated is the maxi­mum allowable temperature rise, T

R

(max). This is calcu-

lated by using the formula:

T

R

(max)=TJ(max) − TA(max)
where:
T

J

(max) is the maximum allowable junction temperature,

which is 125˚C for commercial grade parts.
T

A

(max) is the maximum ambient temperature which will be

encountered in the application.
Using the calculated values for T

R

(max) and PD, the maxi­mum allowable value for the junction-to-ambient thermal re­sistance, θ

(J−A)

, can now be found:

θ

(J−A)

=

T

R

(max)/P

D

The heatsink for the LP2960 is made using the PC board
copper, with the heat generated on the die being conducted
through the lead frame and out to the pins which are sol­dered to the PC board.

The GND pins are the only ones capable of conducting any
significant amount of heat, as they are internally attached to
the lead frame on which the die is mounted.

The figure below shows recommended copper foil patterns
to be used for heatsinking the DIP and Surface Mount pack­ages:

The table below shows measured values of θ

(J−A)

foraPC

board with 1 ounce copper weight:

Package L (in.) H (in.) θ

J−A

(˚C/W)

DIP

1 0.5 50
2 0.2 52

Surface

Mount

1 0.5 72
2 0.2 74

As the heat must transfer from the copper to the surrounding
air, best results (lowest θ

J−A

) will be obtained by using a

sur-

face

copper layer with the solder resist opened up over the

heatsink area.
If an

internal

copper layer of a multi-layer board is used for
heatsinking, the board material acts as an insulator, inhibit­ing heat transfer and increasing θ

J−A

.

As with any heatsink, increasing the airflow across the board
will significantly improve the heat transfer.

Heat Sink Foil Patterns

DS011962-31

www.national.com13

Typical Applications

Low T.C. Current Sink

DS011962-32

5V Bus Current Limiter with Load Fault Indicator

DS011962-33

*

Output voltage equals +VINminus dropout voltage, which varies with

output current. Current limits at a maximum of 1000 mA (typical).

**

Select R1 so that the comparator input voltage is 1.23V at the output

voltage which corresponds to the desired fault current value.

5V Regulator with Error Flags for Low

BATTERY and OUT OF REGULATION

DS011962-34

*

Connect to Logic or µP control inputs.

LOW BATT flag warns the user that the battery has discharged down to
about 5.8V, giving the user time to recharge the battery or power-down
some hardware with high power requirements. The output is still in
regulation at this time.

OUT OF REGULATION flag indicates when the battery is almost
completely discharged, and can be used to initiate a power-down
sequence.

5V Regulator with Snap-ON/Snap-OFF

Feature and Hysteresis

DS011962-35

*

Turns ON at V

IN

=

5.87V

Turns OFF at V

IN

=

5.64V

(for component values shown)

www.national.com 14

Typical Applications (Continued)

5V Regulator with Timed Power-On Reset

DS011962-36

Timing Diagram for Timed Power-On Reset

DS011962-37

*

R

T

=

1 Meg, C

T

=

0.1 µF

www.national.com15

Physical Dimensions inches (millimeters) unless otherwise noted

Order Number LP2960IM-5.0, LP2960AIM-5.0,

LP2960IM-3.3 or LP2960AIM-3.3

NS Package Number M16A

Order Number LP2960IN-5.0, LP2960AIN-5.0,

LP2960IN-3.3 or LP2960AIN-3.3

NS Package Number N16G

www.national.com 16

Notes

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.

2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.

National Semiconductor
Corporation

Americas
Tel: [phone]
Fax: [phone]
Email: [e-mail]

National Semiconductor
Europe

Fax: [phone]

Email: [e-mail]
Deutsch Tel: [phone]
English Tel: [phone]
Français Tel: [phone]
Italiano Tel: [phone]

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Asia Pacific Customer
Response Group

Tel: [phone]
Fax: [phone]
Email: [e-mail]

National Semiconductor
Japan Ltd.

Tel: [phone]
Fax: [phone]

www.national.com

LP2960 Adjustable Micropower 0.5A Low-Dropout Regulators

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.