NSC LM2587T-ADJ, LM2587T-5.0, LM2587T-12, LM2587SX-ADJ, LM2587SX-3.3 Datasheet

LM2587

SIMPLE SWITCHER

®

5A Flyback Regulator

General Description

The LM2587 series of regulators are monolithic integrated

circuits specifically designed for flyback, step-up (boost), and

forward converter applications. The device is available in 4

different output voltage versions: 3.3V, 5.0V,12V,andadjust-

able.

Requiring a minimum number of external components,these

regulators are cost effective, and simple to use. Included in

the datasheet are typical circuits of boostandflybackregula-

tors.Alsolistedare selector guides for diodes and capacitors

and a family of standard inductors and flyback transformers

designed to work with these switching regulators.

The power switch is a 5.0A NPN device that can stand-off

65V. Protecting the power switch are current and thermal

limiting circuits, and an undervoltage lockout circuit. This IC

contains a 100 kHz fixed-frequency internal oscillator that

permits the use of small magnetics. Other features include

soft start mode to reducein-rush current during start up, cur-

rent mode control forimproved rejection of input voltage and

output load transients and cycle-by-cycle current limiting.An

output voltage tolerance of

±

4

%

, within specified input volt-

ages and output load conditions, is guaranteedforthepower

supply system.

Features

n Requires few external components

n Family of standard inductors and transformers

n NPN output switches 5.0A, can stand off 65V

n Wide input voltage range: 4V to 40V

n Current-mode operation for improved transient

response, line regulation, and current limit

n 100 kHz switching frequency

n Internal soft-start function reduces in-rush current during

start-up

n Output transistor protected by current limit, under

voltage lockout, and thermal shutdown

n System Output Voltage Tolerance of

±

4

%

max over line

and load conditions

Typical Applications

n Flyback regulator

n Multiple-output regulator

n Simple boost regulator

n Forward converter

Flyback Regulator

Ordering Information

Package Type NSC Package Order Number

Drawing

5-Lead TO-220 Bent, Staggered Leads T05D LM2587T-3.3, LM2587T-5.0, LM2587T-12, LM2587T-ADJ

5-Lead TO-263 TS5B LM2587S-3.3, LM2587S-5.0, LM2587S-12, LM2587S-ADJ

5-Lead TO-263 Tape and Reel TS5B LM2587SX-3.3, LM2587SX-5.0, LM2587SX-12,

LM2587SX-ADJ

SIMPLE SWITCHER

®

and

Switchers Made Simple

®

are registered trademarks of National SemiconductorCorporation.

DS012316-1

April 1998

LM2587 SIMPLE SWITCHER 5A Flyback Regulator

© 1999 National Semiconductor Corporation DS012316 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.

Input Voltage −0.4V ≤ V

IN

≤ 45V

Switch Voltage −0.4V ≤ V

SW

≤ 65V

Switch Current (Note 2) Internally Limited

Compensation Pin Voltage −0.4V ≤ V

COMP

≤ 2.4V

Feedback Pin Voltage −0.4V ≤ V

FB

≤ 2V

OUT

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

Lead Temperature

(Soldering, 10 sec.) 260˚C

Maximum Junction

Temperature (Note 3) 150˚C

Power Dissipation (Note 3) Internally Limited

Minimum ESD Rating

(C

=

100 pF, R

=

1.5 kΩ 2kV

Operating Ratings

Supply Voltage 4V ≤ V

IN

≤ 40V

Output Switch Voltage 0V ≤ V

SW

≤ 60V

Output Switch Current I

SW

≤ 5.0A

Junction Temperature Range −40˚C ≤ T

J

≤ +125˚C

LM2587-3.3

Electrical Characteristics

Specifications with standard type face are for T

J

=

25˚C, and those in bold type face apply over full Operating Temperature

Range. Unless otherwise specified, V

IN

=

5V.

Symbol Parameters Conditions Typical Min Max Units

SYSTEM PARAMETERS Test Circuit of

Figure 2

(Note 4)

V

OUT

Output Voltage V

IN

=

4V to 12V 3.3 3.17/3.14 3.43/3.46 V

I

LOAD

=

400 mA to 1.75A

∆V

OUT

/ Line Regulation V

IN

=

4V to 12V 20 50/100 mV

∆V

IN

I

LOAD

=

400 mA

∆V

OUT

/ Load Regulation V

IN

=

12V 20 50/100 mV

∆I

LOAD

I

LOAD

=

400 mA to 1.75A

η Efficiency V

IN

=

12V, I

LOAD

=

1A 75

%

UNIQUE DEVICE PARAMETERS (Note 5)

V

REF

Output Reference Measured at Feedback Pin 3.3 3.242/3.234 3.358/3.366 V

Voltage V

COMP

=

1.0V

∆V

REF

Reference Voltage V

IN

=

4V to 40V 2.0 mV

Line Regulation

G

M

Error Amp I

COMP

=

−30 µA to +30 µA 1.193 0.678 2.259 mmho

Transconductance V

COMP

=

1.0V

A

VOL

Error Amp V

COMP

=

0.5V to 1.6V 260 151/75 V/V

Voltage Gain R

COMP

=

1.0 MΩ (Note 6)

LM2587-5.0

Electrical Characteristics

Specifications with standard type face are for T

J

=

25˚C, and those in bold type face apply over full Operating Temperature

Range. Unless otherwise specified, V

IN

=

5V.

Symbol Parameters Conditions Typical Min Max Units

SYSTEM PARAMETERS Test Circuit of

Figure 2

(Note 4)

V

OUT

Output Voltage V

IN

=

4V to 12V 5.0 4.80/4.75 5.20/5.25 V

I

LOAD

=

500 mA to 1.45A

∆V

OUT

/ Line Regulation V

IN

=

4V to 12V 20 50/100 mV

∆V

IN

I

LOAD

=

500 mA

∆V

OUT

/ Load Regulation V

IN

=

12V 20 50/100 mV

∆I

LOAD

I

LOAD

=

500 mA to 1.45A

η Efficiency V

IN

=

12V, I

LOAD

=

750 mA 80

%

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LM2587-5.0

Electrical Characteristics

(Continued)

Symbol Parameters Conditions Typical Min Max Units

UNIQUE DEVICE PARAMETERS (Note 5)

V

REF

Output Reference Measured at Feedback Pin 5.0 4.913/4.900 5.088/5.100 V

Voltage V

COMP

=

1.0V

∆V

REF

Reference Voltage V

IN

=

4V to 40V 3.3 mV

Line Regulation

G

M

Error Amp I

COMP

=

−30 µA to +30 µA 0.750 0.447 1.491 mmho

Transconductance V

COMP

=

1.0V

A

VOL

Error Amp V

COMP

=

0.5V to 1.6V 165 99/49 V/V

Voltage Gain R

COMP

=

1.0 MΩ (Note 6)

LM2587-12

Electrical Characteristics

Specifications with standard type face are for T

J

=

25˚C, and those in bold type face apply over full Operating Temperature

Range. Unless otherwise specified, V

IN

=

5V.

Symbol Parameters Conditions Typical Min Max Units

SYSTEM PARAMETERS Test Circuit of

Figure 3

(Note 4)

V

OUT

Output Voltage V

IN

=

4V to 10V 12.0 11.52/11.40 12.48/12.60 V

I

LOAD

=

300 mA to 1.2A

∆V

OUT

/ Line Regulation V

IN

=

4V to 10V 20 100/200 mV

∆V

IN

I

LOAD

=

300 mA

∆V

OUT

/ Load Regulation V

IN

=

10V 20 100/200 mV

∆I

LOAD

I

LOAD

=

300 mA to 1.2A

η Efficiency V

IN

=

10V, I

LOAD

=

1A 90

%

UNIQUE DEVICE PARAMETERS (Note 5)

V

REF

Output Reference Measured at Feedback Pin 12.0 11.79/11.76 12.21/12.24 V

Voltage V

COMP

=

1.0V

∆V

REF

Reference Voltage V

IN

=

4V to 40V 7.8 mV

Line Regulation

G

M

Error Amp I

COMP

=

−30 µA to +30 µA 0.328 0.186 0.621 mmho

Transconductance V

COMP

=

1.0V

A

VOL

Error Amp V

COMP

=

0.5V to 1.6V 70 41/21 V/V

Voltage Gain R

COMP

=

1.0 MΩ (Note 6)

LM2587-ADJ

Electrical Characteristics

Specifications with standard type face are for T

J

=

25˚C, and those in bold type face apply over full Operating Temperature

Range. Unless otherwise specified, V

IN

=

5V.

Symbol Parameters Conditions Typical Min Max Units

SYSTEM PARAMETERS Test Circuit of

Figure 3

(Note 4)

V

OUT

Output Voltage V

IN

=

4V to 10V 12.0 11.52/11.40 12.48/12.60 V

I

LOAD

=

300 mA to 1.2A

∆V

OUT

/ Line Regulation V

IN

=

4V to 10V 20 100/200 mV

∆V

IN

I

LOAD

=

300 mA

∆V

OUT

/ Load Regulation V

IN

=

10V 20 100/200 mV

∆I

LOAD

I

LOAD

=

300 mA to 1.2A

η Efficiency V

IN

=

10V, I

LOAD

=

1A 90

%

www.national.com3

LM2587-ADJ

Electrical Characteristics

(Continued)

Symbol Parameters Conditions Typical Min Max Units

UNIQUE DEVICE PARAMETERS (Note 5)

V

REF

Output Reference Measured at Feedback Pin 1.230 1.208/1.205 1.252/1.255 V

Voltage V

COMP

=

1.0V

∆V

REF

Reference Voltage V

IN

=

4V to 40V 1.5 mV

Line Regulation

G

M

Error Amp I

COMP

=

−30 µA to +30 µA 3.200 1.800 6.000 mmho

Transconductance V

COMP

=

1.0V

A

VOL

Error Amp V

COMP

=

0.5V to 1.6V 670 400/200 V/V

Voltage Gain R

COMP

=

1.0 MΩ (Note 6)

I

B

Error Amp V

COMP

=

1.0V 125 425/600 nA

Input Bias Current

All Output Voltage Versions

Electrical Characteristics

(Note 5)

Specifications with standard type face are for T

J

=

25˚C, and those in bold type face apply over full Operating Temperature

Range. Unless otherwise specified, V

IN

=

5V.

Symbol Parameters Conditions Typical Min Max Units

I

S

Input Supply Current (Switch Off) 11 15.5/16.5 mA

(Note 8)

I

SWITCH

=

3.0A 85 140 165 mA

V

UV

Input Supply R

LOAD

=

100Ω 3.30 3.05 3.75 V

Undervoltage Lockout

f

O

Oscillator Frequency Measured at Switch Pin

R

LOAD

=

100Ω 100 85/75 115/125 kHz

V

COMP

=

1.0V

f

SC

Short-Circuit Measured at Switch Pin

Frequency R

LOAD

=

100Ω 25 kHz

V

FEEDBACK

=

1.15V

V

EAO

Error Amplifier Upper Limit 2.8 2.6/2.4 V

Output Swing (Note 7)

Lower Limit 0.25 0.40/0.55 V

(Note 8)

I

EAO

Error Amp (Note 9)

Output Current 165 110/70 260/320 µA

(Source or Sink)

I

SS

Soft Start Current V

FEEDBACK

=

0.92V 11.0 8.0/7.0 17.0/19.0 µA

V

COMP

=

1.0V

D Maximum Duty Cycle R

LOAD

=

100Ω 98 93/90

%

(Note 7)

I

L

Switch Leakage Switch Off 15 300/600 µA

Current V

SWITCH

=

60V

V

SUS

Switch Sustaining dV/dT

=

1.5V/ns 65 V

Voltage

V

SAT

Switch Saturation I

SWITCH

=

5.0A 0.7 1.1/1.4 V

Voltage

I

CL

NPN Switch 6.5 5.0 9.5 A

Current Limit

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All Output Voltage Versions

Electrical Characteristics

(Note 5) (Continued)

Symbol Parameters Conditions Typical Min Max Units

COMMON DEVICE PARAMETERS (Note 4)

θ

JA

Thermal Resistance T Package, Junction to Ambient

(Note 10)

65

θ

JA

T Package, Junction to Ambient

(Note 11)

45

θ

JC

T Package, Junction to Case 2

θ

JA

S Package, Junction to Ambient

(Note 12)

56

˚C/W

θ

JA

S Package, Junction to Ambient

(Note 13)

35

θ

JA

S Package, Junction to Ambient

(Note 14)

26

θ

JC

S Package, Junction to Case 2

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings indicate conditions the device is intended to

be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions, see the Electrical

Characteristics.

Note 2: Note that switch current and output current are not identical in a step-up regulator. Output current cannot be internally limited when the LM2587 is used as

a step-up regulator. To prevent damage to the switch, the output current must be externally limited to 5A. However, output current is internally limited when the

LM2587 is used as a flyback regulator (see the Application Hints section for more information).

Note 3: The junction temperature of the device (T

J

) is a function of the ambient temperature (T

A

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

JA

), and the power

dissipation of the device (P

D

). A thermal shutdown will occur if the temperature exceedsthe maximum junction temperature of the device: P

D

x θ

JA

+T

A(MAX)

≥ T

J

-

(MAX)

. For a safe thermal design, check that the maximum power dissipated by the device is less than: P

D

≤ [T

J(MAX)

−T

A(MAX)

)]/θ

JA

. When calculating the maximum

allowable power dissipation, derate the maximum junction temperature — this ensures a margin of safety in the thermal design.

Note 4: External components such as the diode, inductor, input and output capacitors can affect switching regulator performance. When the LM2587 is used as

shown in

Figure 2

and

Figure 3

, system performance will be as specified by the system parameters.

Note 5: All room temperature limits are 100

%

production tested, and all limits at temperature extremes are guaranteed via correlation using standard Statistical Qual-

ity Control (SQC) methods.

Note 6: A 1.0 MΩ resistor is connected to the compensation pin (which is the error amplifier output) to ensure accuracy in measuringA

VOL

.

Note 7: Tomeasure this parameter, the feedback voltage is set to a low value, depending on the output version of the device, to force the error amplifier output high.

Adj: V

FB

=

1.05V; 3.3V: V

FB

=

2.81V; 5.0V: V

FB

=

4.25V; 12V: V

FB

=

10.20V.

Note 8: Tomeasure this parameter, the feedback voltage is set to a high value, depending on the output version of the device, to force the error amplifier output low.

Adj: V

FB

=

1.41V; 3.3V: V

FB

=

3.80V; 5.0V: V

FB

=

5.75V; 12V: V

FB

=

13.80V.

Note 9: Tomeasure the worst-case error amplifier output current, the LM2587 is tested with the feedback voltage set to its low value (specified in Note 7) and at its

high value (specified in Note 8).

Note 10: Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically,with

1

⁄

2

inch leads in a socket, or on a PC

board with minimum copper area.

Note 11: Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically,with

1

⁄

2

inch leads soldered to a PC board

containing approximately 4 square inches of (1oz.) copper area surrounding the leads.

Note 12: Junction to ambient thermal resistance for the 5 lead TO-263 mounted horizontally against a PC board area of 0.136 square inches (the same size as the

TO-263 package) of 1 oz. (0.0014 in. thick) copper.

Note 13: Junction to ambient thermal resistance for the 5 leadTO-263 mounted horizontally against a PC board areaof 0.4896 square inches (3.6 times the area

of the TO-263 package) of 1 oz. (0.0014 in. thick) copper.

Note 14: Junction to ambient thermal resistance for the 5 lead TO-263 mounted horizontally against a PC board copper area of 1.0064 square inches (7.4 times the

area of the TO-263 package) of 1 oz. (0.0014 in. thick) copper.Additional copper area will reduce thermal resistance further. See the thermal model in Switchers Made

Simple

®

software.

www.national.com5

Typical Performance Characteristics

Supply Current

vs Temperature

DS012316-48

Reference Voltage

vs Temperature

DS012316-49

∆Reference Voltage

vs Supply Voltage

DS012316-50

Supply Current

vs Switch Current

DS012316-51

Current Limit

vs Temperature

DS012316-52

Feedback Pin Bias

Current vs Temperature

DS012316-53

Switch Saturation

Voltage vs Temperature

DS012316-54

Switch Transconductance

vs Temperature

DS012316-55

Oscillator Frequency

vs Temperature

DS012316-56

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Typical Performance Characteristics (Continued)

Connection Diagrams

Error Amp Transconductance

vs Temperature

DS012316-57

Error Amp Voltage

Gain vs Temperature

DS012316-58

Short Circuit Frequency

vs Temperature

DS012316-59

Bent, Staggered Leads

5-Lead TO-220 (T)

Top View

DS012316-3

Bent, Staggered Leads

5-Lead TO-220 (T)

Side View

DS012316-4

Order Number LM2587T-3.3, LM2587T-5.0,

LM2587T-12 or LM2587T-ADJ

See NS Package Number T05D

5-Lead TO-263 (S)

Top View

DS012316-5

5-Lead TO-263 (S)

Side View

DS012316-6

Order Number LM2587S-3.3, LM2587S-5.0,

LM2587S-12 or LM2587S-ADJ

See NS Package Number TS5B

www.national.com7

Block Diagram

DS012316-7

For Fixed Versions

3.3V, R1

=

3.4k, R2

=

2k

5V, R1

=

6.15k, R2

=

2k

12V, R1

=

8.73k, R2

=

1k

For Adj. Version

R1

=

Short (0Ω), R2

=

Open

FIGURE 1.

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