National Semiconductor LM1577, LM2577 Technical data

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LM1577/LM2577
SIMPLE SWITCHER

®

Step-Up Voltage Regulator

LM1577/LM2577 SIMPLE SWITCHER Step-Up Voltage Regulator

April 2005

General Description

The LM1577/LM2577 are monolithic integrated circuits that
provide all of the power and control functions for step-up
(boost), flyback, and forward converter switching regulators.
The device is available in three different output voltage
versions: 12V, 15V, and adjustable.

Requiring a minimum number of external components, these
regulators are cost effective, and simple to use. Listed in this
data sheet are a family of standard inductors and flyback
transformers designed to work with these switching regula­tors.

Included on the chip is a 3.0A NPN switch and its associated
protection circuitry, consisting of current and thermal limiting,
and undervoltage lockout. Other features include a 52 kHz
fixed-frequency oscillator that requires no external compo­nents, a soft start mode to reduce in-rush current during
start-up, and current mode control for improved rejection of
input voltage and output load transients.

Connection Diagrams

Straight Leads

5-Lead TO-220 (T)

Features

n Requires few external components
n NPN output switches 3.0A, can stand off 65V
n Wide input voltage range: 3.5V to 40V
n Current-mode operation for improved transient

response, line regulation, and current limit

n 52 kHz internal oscillator
n Soft-start function reduces in-rush current during start-up
n Output switch protected by current limit, under-voltage

lockout, and thermal shutdown

Typical Applications

n Simple boost regulator
n Flyback and forward regulators
n Multiple-output regulator

Bent, Staggered Leads

5-Lead TO-220 (T)

Top View

Order Number LM2577T-12, LM2577T-15,

or LM2577T-ADJ

See NS Package Number T05A

SIMPLE SWITCHER®is a registered trademark of National Semiconductor Corporation.

© 2005 National Semiconductor Corporation DS011468 www.national.com

01146804

Top View

Order Number LM2577T-12 Flow LB03, LM2577T-15

Flow LB03, or LM2577T-ADJ Flow LB03

See NS Package Number T05D

01146805

Connection Diagrams (Continued)

16-Lead DIP (N) 24-Lead Surface Mount (M)

LM1577/LM2577

*No internal Connection

Order Number LM2577N-12, LM2577N-15,

See NS Package Number N16A

5-Lead Surface-Mount Package

Top View

or LM2577N-ADJ

TO-263 (S)

Top View

01146806

01146832

*No internal Connection

01146807

Top View

Order Number LM2577M-12, LM2577M-15,

or LM2577M-ADJ

See NS Package Number M24B

01146833

Side View

Order Number LM2577S-12, LM2577S-15,

or LM2577S-ADJ

See NS Package Number TS5B

4-Lead TO-3 (K)

Bottom View

Order Number LM1577K-12/883, LM1577K-15/883,

or LM1577K-ADJ/883

See NS Package Number K04A

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01146808

Ordering Information

LM1577/LM2577

Temperature

Range

−40˚C ≤ T

≤ +125˚C 24-Pin Surface

A

Mount

16-Pin Molded DIP LM2577N-12 LM2577N-15 LM2577N-ADJ N16A N

5-Lead Surface
Mount

5-Straight Leads LM2577T-12 LM2577T-15 LM2577T-ADJ T05A TO-220

5-Bent Staggered LM2577T-12 LM2577T-15 LM2577T-ADJ T05D TO-220

Leads Flow LB03 Flow LB03 Flow LB03

−55˚C ≤ T

≤ +150˚C 4-Pin TO-3 LM1577K-12/883LM1577K-15/883 LM1577K-

A

Typical Application

Package

Type

Output Voltage NSC

12V 15V ADJ Package Package

Drawing

LM2577M-12 LM2577M-15 LM2577M-ADJ M24B SO

LM2577S-12 LM2577S-15 LM2577S-ADJ TS5B TO-263

K04A TO-3

ADJ/883

Note: Pin numbers shown are for TO-220 (T) package.

01146801

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

Minimum ESD Rating

(C = 100 pF, R = 1.5 kΩ)2kV

please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Operating Ratings

Supply Voltage 45V

LM1577/LM2577

Output Switch Voltage 65V

Output Switch Current (Note 2) 6.0A

Power Dissipation Internally Limited

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

Lead Temperature

(Soldering, 10 sec.) 260˚C

Supply Voltage 3.5V ≤ VIN≤ 40V

Output Switch Voltage 0V ≤ V

Output Switch Current I

SWITCH

Junction Temperature Range

LM1577 −55˚C ≤ T

LM2577 −40˚C ≤ T

Maximum Junction Temperature 150˚C

Electrical Characteristics—LM1577-12, LM2577-12

Specifications with standard type face are for TJ= 25˚C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, V

= 5V, and I

IN

Symbol Parameter Conditions Typical Limit Limit (Limits)

SYSTEM PARAMETERS Circuit of Figure 1 (Note 6)

V

OUT

Output Voltage VIN= 5V to 10V 12.0 V

I

= 100 mA to 800 mA 11.60/11.40 11.60/11.40 V(min)

LOAD

(Note 3) 12.40/12.60 12.40/12.60 V(max)

Line Regulation VIN= 3.5V to 10V 20 mV

I

= 300 mA 50/100 50/100 mV(max)

LOAD

Load Regulation VIN=5V 20 mV

I

= 100 mA to 800 mA 50/100 50/100 mV(max)

LOAD

η Efficiency V

= 5V, I

IN

LOAD

DEVICE PARAMETERS

I

S

V

UV

Input Supply Current V

Input Supply I

FEEDBACK

I

SWITCH

V

COMP

SWITCH

= 14V (Switch Off) 7.5 mA

= 2.0A 25 mA

= 2.0V (Max Duty Cycle) 50/85 50/85 mA(max)

= 100 mA 2.90 V

Undervoltage Lockout 2.70/2.65 2.70/2.65 V(min)

f

O

V

REF

Oscillator Frequency Measured at Switch Pin 52 kHz

I

= 100 mA 48/42 48/42 kHz(min)

SWITCH

Output Reference Measured at Feedback Pin V

Voltage V

= 3.5V to 40V 12 11.76/11.64 11.76/11.64 V(min)

IN

V

= 1.0V 12.24/12.36 12.24/12.36 V(max)

COMP

Output Reference VIN= 3.5V to 40V

Voltage Line Regulator

R

FB

Feedback Pin Input 9.7 kΩ

Resistance

G

M

Error Amp I

Transconductance V

= −30 µA to +30 µA 370 µmho

COMP

= 1.0V 225/145 225/145 µmho(min)

COMP

=0.

SWITCH

LM1577-12 LM2577-12 Units

(Notes 3, 4) (Note 5)

= 800 mA 80 %

10.0/14.0 10.0/14.0 mA(max)

3.10/3.15 3.10/3.15 V(max)

56/62 56/62 kHz(max)

7mV

515/615 515/615 µmho(max)

SWITCH

J

J

≤ 60V

≤ 3.0A

≤ +150˚C

≤ +125˚C

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Electrical Characteristics— LM1577-12, LM2577-12 (Continued)

Specifications with standard type face are for TJ= 25˚C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, V

= 5V, and I

IN

Symbol Parameter Conditions Typical Limit Limit (Limits)

DEVICE PARAMETERS

A

VOL

Error Amp V

Voltage Gain R

= 1.1V to 1.9V 80 V/V

COMP

= 1.0 MΩ 50/25 50/25 V/V(min)

COMP

(Note 7)

Error Amplifier Upper Limit 2.4 V

Output Swing V

FEEDBACK

= 10.0V 2.2/2.0 2.2/2.0 V(min)

Lower Limit 0.3 V

Error Amplifier V

Output Current V

I

SS

Soft Start Current V

D Maximum Duty Cycle V

V

FEEDBACK

FEEDBACK

COMP

FEEDBACK

V

COMP

COMP

I

SWITCH

= 15.0V 0.40/0.55 0.40/0.55 V(max)

= 10.0V to 15.0V

= 1.0V

= 10.0V 5.0 µA

= 0V 2.5/1.5 2.5/1.5 µA(min)

= 1.5V 95 %

= 100 mA 93/90 93/90 %(min)

Switch
Transconductance

SWITCH

=0.

LM1577-12 LM2577-12 Units

(Notes 3, 4) (Note 5)

±

200 µA

±

130/±90

±

300/±400±300/±400 µA(max)

±

130/±90 µA(min)

7.5/9.5 7.5/9.5 µA(max)

12.5 A/V

LM1577/LM2577

I

L

Switch Leakage V

Current V

V

SAT

Switch Saturation I

SWITCH

Voltage V

= 65V 10 µA

SWITCH

FEEDBACK

= 15V (Switch Off) 300/600 300/600 µA(max)

= 2.0A 0.5 V

= 2.0V (Max Duty Cycle) 0.7/0.9 0.7/0.9 V(max)

COMP

NPN Switch 4.5 A

Current Limit 3.7/3.0 3.7/3.0 A(min)

5.3/6.0 5.3/6.0 A(max)

Electrical Characteristics— LM1577-15, LM2577-15

Specifications with standard type face are for TJ= 25˚C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, V

= 5V, and I

IN

Symbol Parameter Conditions Typical Limit Limit (Limits)

SYSTEM PARAMETERS Circuit of Figure 2 (Note 6)

V

OUT

Output Voltage VIN= 5V to 12V 15.0 V

I

= 100 mA to 600 mA 14.50/14.25 14.50/14.25 V(min)

LOAD

(Note 3) 15.50/15.75 15.50/15.75 V(max)

Line Regulation VIN= 3.5V to 12V 20

= 300 mA mV(max)

I

LOAD

Load Regulation VIN=5V 20

I

= 100 mA to 600 mA mV(max)

LOAD

η Efficiency V

IN

= 5V, I

=0.

SWITCH

LM1577-15 LM2577-15 Units

(Notes 3, 4) (Note 5)

50/100 50/100

50/100 50/100

= 600 mA 80 %

LOAD

mV

mV

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Electrical Characteristics— LM1577-15, LM2577-15 (Continued)

Specifications with standard type face are for TJ= 25˚C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, V

= 5V, and I

IN

Symbol Parameter Conditions Typical Limit Limit (Limits)

LM1577/LM2577

DEVICE PARAMETERS

I

S

V

UV

f

O

V

REF

R

FB

G

M

A

VOL

I

SS

D Maximum Duty V

Input Supply Current V

FEEDBACK

(Switch Off) 10.0/14.0 10.0/14.0 mA(max)

I

V

= 2.0A 25 mA

SWITCH

= 2.0V 50/85 50/85 mA(max)

COMP

(Max Duty Cycle)

Input Supply I

= 100 mA 2.90 V

SWITCH

Undervoltage 2.70/2.65 2.70/2.65 V(min)

Lockout 3.10/3.15 3.10/3.15 V(max)

Oscillator Frequency Measured at Switch Pin 52 kHz

I

= 100 mA 48/42 48/42 kHz(min)

SWITCH

Output Reference Measured at Feedback Pin V

Voltage V

= 3.5V to 40V 15 14.70/14.55 14.70/14.55 V(min)

IN

V

= 1.0V 15.30/15.45 15.30/15.45 V(max)

COMP

Output Reference VIN= 3.5V to 40V 10 mV

Voltage Line Regulation

Feedback Pin Input 12.2 kΩ

Voltage Line Regulator

Error Amp I

Transconductance V

Error Amp V

Voltage Gain R

= −30 µA to +30 µA 300 µmho

COMP

= 1.0V 170/110 170/110 µmho(min)

COMP

= 1.1V to 1.9V 65 V/V

COMP

= 1.0 MΩ 40/20 40/20 V/V(min)

COMP

(Note 7)

Error Amplifier Upper Limit 2.4 V

Output Swing V

FEEDBACK

Lower Limit 0.3 V

V

FEEDBACK

Error Amp V

Output Current V

Soft Start Current V

Cycle I

FEEDBACK

= 1.0V

COMP

FEEDBACK

V

= 0V 2.5/1.5 2.5/1.5 µA(min)

COMP

= 1.5V 95 %

COMP

= 100 mA 93/90 93/90 %(min)

SWITCH

Switch
Transconductance

=0.

SWITCH

LM1577-15 LM2577-15 Units

(Notes 3, 4) (Note 5)

= 18.0V 7.5 mA

56/62 56/62 kHz(max)

420/500 420/500 µmho(max)

= 12.0V 2.2/2.0 2.2/2.0 V(min)

= 18.0V 0.4/0.55 0.40/0.55 V(max)

= 12.0V to 18.0V

±

200 µA

±

130/±90

±

300/±400±300/±400 µA(max)

±

130/±90 µA(min)

= 12.0V 5.0 µA

7.5/9.5 7.5/9.5 µA(max)

12.5 A/V

I

L

Switch Leakage V

Current V

= 65V 10 µA

SWITCH

FEEDBACK

= 18.0V 300/600 300/600 µA(max)

(Switch Off)

V

SAT

Switch Saturation I

Voltage V

= 2.0A 0.5 V

SWITCH

= 2.0V 0.7/0.9 0.7/0.9 V(max)

COMP

(Max Duty Cycle)

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Electrical Characteristics— LM1577-15, LM2577-15 (Continued)

Specifications with standard type face are for TJ= 25˚C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, V

= 5V, and I

IN

SWITCH

=0.

LM1577-15 LM2577-15 Units

Symbol Parameter Conditions Typical Limit Limit (Limits)

(Notes 3, 4) (Note 5)

DEVICE PARAMETERS

NPN Switch V

= 2.0V 4.3 A

COMP

Current Limit 3.7/3.0 3.7/3.0 A(min)

5.3/6.0 5.3/6.0 A(max)

Electrical Characteristics— LM1577-ADJ, LM2577-ADJ

Specifications with standard type face are for TJ= 25˚C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, V

= 5V, V

IN

FEEDBACK

Symbol Parameter Conditions Typical Limit Limit (Limits)

SYSTEM PARAMETERS Circuit of Figure 3 (Note 6)

V

OUT

Output Voltage VIN= 5V to 10V 12.0 V

I

= 100 mA to 800 mA 11.60/11.40 11.60/11.40 V(min)

LOAD

(Note 3) 12.40/12.60 12.40/12.60 V(max)

∆V

/ Line Regulation VIN= 3.5V to 10V 20 mV

OUT

∆V

IN

∆V

/ Load Regulation VIN=5V 20 mV

OUT

∆I

LOAD

η Efficiency V

I

= 300 mA 50/100 50/100 mV(max)

LOAD

I

= 100 mA to 800 mA 50/100 50/100 mV(max)

LOAD

= 5V, I

IN

LOAD

DEVICE PARAMETERS

I

S

V

UV

Input Supply Current V

Input Supply I

FEEDBACK

I

SWITCH

V

COMP

SWITCH

= 1.5V (Switch Off) 7.5 mA

= 2.0A 25 mA

= 2.0V (Max Duty Cycle) 50/85 50/85 mA(max)

= 100 mA 2.90 V

Undervoltage Lockout 2.70/2.65 2.70/2.65 V(min)

f

O

V

∆V

∆V

I

B

REF

REF

IN

Oscillator Frequency Measured at Switch Pin 52 kHz

I

= 100 mA 48/42 48/42 kHz(min)

SWITCH

Reference Measured at Feedback Pin V

Voltage V

= 3.5V to 40V 1.230 1.214/1.206 1.214/1.206 V(min)

IN

V

= 1.0V 1.246/1.254 1.246/1.254 V(max)

COMP

/ Reference Voltage VIN= 3.5V to 40V 0.5 mV

Line Regulation

Error Amp V

= 1.0V 100 nA

COMP

Input Bias Current 300/800 300/800 nA(max)

G

M

A

VOL

Error Amp I

Transconductance V

Error Amp V

Voltage Gain R

= −30 µA to +30 µA 3700 µmho

COMP

= 1.0V 2400/1600 2400/1600 µmho(min)

COMP

= 1.1V to 1.9V 800 V/V

COMP

= 1.0 MΩ (Note 7) 500/250 500/250 V/V(min)

COMP

=V

REF

, and I

SWITCH

=0.

LM1577-ADJ LM2577-ADJ Units

(Notes 3, 4) (Note 5)

= 800 mA 80 %

10.0/14.0 10.0/14.0 mA(max)

3.10/3.15 3.10/3.15 V(max)

56/62 56/62 kHz(max)

4800/5800 4800/5800 µmho(max)

LM1577/LM2577

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Electrical Characteristics— LM1577-ADJ, LM2577-ADJ (Continued)

Specifications with standard type face are for TJ= 25˚C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, V

= 5V, V

IN

FEEDBACK

Symbol Parameter Conditions Typical Limit Limit (Limits)

LM1577/LM2577

DEVICE PARAMETERS

Error Amplifier Upper Limit 2.4 V

Output Swing V

FEEDBACK

Lower Limit 0.3 V

V

FEEDBACK

Error Amp V

Output Current V

I

SS

Soft Start Current V

D Maximum Duty Cycle V

∆I

∆V

I

L

/ Switch 12.5 A/V

SWITCH

COMP

Transconductance

Switch Leakage V

Current V

V

SAT

Switch Saturation I

Voltage V

NPN Switch V

FEEDBACK

COMP

FEEDBACK

V

COMP

COMP

I

SWITCH

SWITCH

FEEDBACK

SWITCH

COMP

COMP

Current Limit 3.7/3.0 3.7/3.0 A(min)

THERMAL PARAMETERS (All Versions)

θ

JA

θ

JC

θ

JA

θ

JC

θ

JA

Thermal Resistance K Package, Junction to Ambient 35

K Package, Junction to Case 1.5

T Package, Junction to Ambient 65

T Package, Junction to Case 2

N Package, Junction to 85

Ambient (Note 8)

θ

JA

M Package, Junction 100

to Ambient (Note 8)

θ

JA

S Package, Junction to 37

Ambient (Note 9)

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: Due to timing considerations of the LM1577/LM2577 current limit circuit, output current cannot be internally limited when the LM1577/LM2577 is used as
a step-up regulator. To prevent damage to the switch, its current must be externally limited to 6.0A. However, output current is internally limited when the
LM1577/LM2577 is used as a flyback or forward converter regulator in accordance to the Application Hints.

Note 3: All limits guaranteed at room temperature (standard type face) and at temperature extremes (boldface type). All limits are used to calculate Outgoing Quality
Level, and are 100% production tested.

Note 4: A military RETS electrical test specification is available on request. At the time of printing, the LM1577K-12/883, LM1577K-15/883, and LM1577K-ADJ/883
RETS specifications complied fully with the boldface limits in these columns. The LM1577K-12/883, LM1577K-15/883, and LM1577K-ADJ/883 may also be procured
to Standard Military Drawing specifications.

Note 5: All limits guaranteed at room temperature (standard type face) and at temperature extremes (boldface type). All room temperature limits are 100%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.

Note 6: External components such as the diode, inductor, input and output capacitors can affect switching regulator performance. When the LM1577/LM2577 is
used as shown in the Test Circuit, system performance will be as specified by the system parameters.

Note 7: A 1.0 MΩ resistor is connected to the compensation pin (which is the error amplifier’s output) to ensure accuracy in measuring A
this pin’s load resistance should be ≥10 MΩ, resulting in A

= 1.0V 2.2/2.0 2.2/2.0 V(min)

= 1.5V 0.40/0.55 0.40/0.55 V(max)

= 1.0V to 1.5V

= 1.0V

= 1.0V 5.0 µA

= 0V 2.5/1.5 2.5/1.5 µA(min)

= 1.5V 95 %

= 100 mA 93/90 93/90 %(min)

= 65V 10 µA

= 1.5V (Switch Off) 300/600 300/600 µA(max)

= 2.0A 0.5 V

= 2.0V (Max Duty Cycle) 0.7/0.9 0.7/0.9 V(max)

= 2.0V 4.3 A

that is typically twice the guaranteed minimum limit.

VOL

=V

REF

, and I

=0.

SWITCH

LM1577-ADJ LM2577-ADJ Units

(Notes 3, 4) (Note 5)

±

200 µA

±

130/±90

±

300/±400±300/±400 µA(max)

±

130/±90 µA(min)

7.5/9.5 7.5/9.5 µA(max)

5.3/6.0 5.3/6.0 A(max)

. In actual applications,

VOL

˚C/W

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Electrical Characteristics— LM1577-ADJ, LM2577-ADJ (Continued)

Note 8: Junction to ambient thermal resistance with approximately 1 square inch of pc board copper surrounding the leads. Additional copper area will lower thermal

resistance further. See thermal model in “Switchers Made Simple” software.

Note 9: If the TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally connected to the package. Using

0.5 square inches of copper area, θ

is 50˚C/W; with 1 square inch of copper area, θJAis 37˚C/W; and with 1.6 or more square inches of copper area, θJAis 32˚C/W.

JA

Typical Performance Characteristics

LM1577/LM2577

Reference Voltage

vs Temperature

Reference Voltage

vs Temperature

Reference Voltage

vs Temperature

01146834 01146835

∆ Reference Voltage

vs Supply Voltage

∆ Reference Voltage

vs Supply Voltage

01146836 01146837

∆ Reference Voltage

vs Supply Voltage

01146838

01146839

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Typical Performance Characteristics (Continued)

LM1577/LM2577

Error Amp Transconductance

vs Temperature

Error Amp Transconductance

vs Temperature

01146840

Error Amp Transconductance

vs Temperature

01146841

Error Amp Voltage

Gain vs Temperature

Error Amp Voltage

Gain vs Temperature

01146842

01146843

Error Amp Voltage

Gain vs Temperature

01146844 01146845

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