lm2577sx-adj

Manufacturer Part Numberlm2577sx-adj
DescriptionSimple Switcher Step-up Voltage Regulator
ManufacturerNational Semiconductor Corporation
lm2577sx-adj datasheet
 


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LM1577/LM2577
SIMPLE SWITCHER
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 regula-
tors.
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 compo-
nents, 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)
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
Step-Up Voltage Regulator
®
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
01146804
Order Number LM2577T-12 Flow LB03, LM2577T-15
Flow LB03, or LM2577T-ADJ Flow LB03
See NS Package Number T05D
DS011468
April 2005
Bent, Staggered Leads
5-Lead TO-220 (T)
01146805
Top View
www.national.com

lm2577sx-adj Summary of contents

  • Page 1

    ... Top View Order Number LM2577T-12, LM2577T-15, or LM2577T-ADJ See NS Package Number T05A SIMPLE SWITCHER ® registered trademark of National Semiconductor Corporation. © 2005 National Semiconductor Corporation Step-Up Voltage Regulator ® Features n Requires few external components n NPN output switches 3.0A, can stand off 65V n Wide input voltage range: 3 ...

  • Page 2

    Connection Diagrams 16-Lead DIP (N) *No internal Connection Top View Order Number LM2577N-12, LM2577N-15, or LM2577N-ADJ See NS Package Number N16A TO-263 (S) 5-Lead Surface-Mount Package Top View www.national.com (Continued) 01146806 *No internal Connection Order Number LM2577M-12, LM2577M-15, Order Number ...

  • Page 3

    Ordering Information Temperature Package Range Type −40˚C ≤ T ≤ +125˚C 24-Pin Surface A Mount 16-Pin Molded DIP 5-Lead Surface Mount 5-Straight Leads 5-Bent Staggered Leads −55˚C ≤ T ≤ +150˚C 4-Pin TO-3 A Typical Application Note: Pin numbers shown ...

  • Page 4

    Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage Output Switch Voltage Output Switch Current (Note 2) Power Dissipation Storage Temperature Range Lead Temperature (Soldering, 10 ...

  • Page 5

    Electrical Characteristics—LM1577-12, LM2577-12 Specifications with standard type face are for T Range. Unless otherwise specified, V Symbol Parameter DEVICE PARAMETERS A Error Amp VOL Voltage Gain Error Amplifier Output Swing Error Amplifier Output Current I Soft Start Current SS D ...

  • Page 6

    Electrical Characteristics—LM1577-15, LM2577-15 Specifications with standard type face are for T Range. Unless otherwise specified, V Symbol Parameter DEVICE PARAMETERS I Input Supply Current S V Input Supply UV Undervoltage Lockout f Oscillator Frequency O V Output Reference REF Voltage ...

  • Page 7

    Electrical Characteristics—LM1577-15, LM2577-15 Specifications with standard type face are for T Range. Unless otherwise specified, V Symbol Parameter DEVICE PARAMETERS NPN Switch Current Limit Electrical Characteristics—LM1577-ADJ, LM2577-ADJ Specifications with standard type face are for T Range. Unless otherwise specified, V ...

  • Page 8

    Electrical Characteristics—LM1577-ADJ, LM2577-ADJ Specifications with standard type face are for T Range. Unless otherwise specified, V Symbol Parameter DEVICE PARAMETERS Error Amplifier Output Swing Error Amp Output Current I Soft Start Current SS D Maximum Duty Cycle ∆I / Switch ...

  • Page 9

    Electrical Characteristics—LM1577-ADJ, LM2577-ADJ 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: ...

  • Page 10

    Typical Performance Characteristics Error Amp Transconductance vs Temperature Error Amp Transconductance vs Temperature Error Amp Voltage Gain vs Temperature www.national.com (Continued) Error Amp Transconductance 01146840 01146842 01146844 10 vs Temperature 01146841 Error Amp Voltage Gain vs Temperature 01146843 Error Amp ...

  • Page 11

    Typical Performance Characteristics Quiescent Current vs Temperature Current Limit vs Temperature Switch Saturation Voltage vs Switch Current (Continued) 01146846 Current Limit Response 01146848 Switch Transconductance 01146850 11 Quiescent Current vs Switch Current 01146847 Time vs Overdrive 01146849 vs Temperature 01146851 ...

  • Page 12

    Typical Performance Characteristics Feedback Pin Bias Current vs Temperature Maximum Power Dissipation (TO-263) (Note 9) www.national.com (Continued) 01146852 01146831 12 Oscillator Frequency vs Temperature 01146853 ...

  • Page 13

    LM1577-12, LM2577-12 Test Circuit L = 415-0930 (AIE any manufacturer C = Sprague Type 673D OUT Electrolytic 680 µF, 20V Note: Pin numbers shown are for TO-220 (T) package FIGURE 1. Circuit Used to Specify System Parameters for ...

  • Page 14

    LM1577-ADJ, LM2577-ADJ Test Circuit L = 415-0930 (AIE any manufacturer C = Sprague Type 673D OUT Electrolytic 680 µF, 20V R1 = 48.7k in series with 511Ω (1 5.62k (1%) Note: Pin numbers shown are for ...

  • Page 15

    Application Hints (Continued) STEP-UP (BOOST) REGULATOR Figure 4 shows the LM1577-ADJ/LM2577-ADJ used as a Step-Up Regulator. This is a switching regulator used for producing an output voltage greater than the input supply voltage. The LM1577-12/LM2577-12 and LM1577-15/ LM2577-15 can also ...

  • Page 16

    Application Hints (Continued) ditions for which the LM1577/LM2577 output switch would be operating beyond its switch current rating. The minimum operating voltage for the LM1577/LM2577 is 3.5V. From here, proceed to step C. 2. For Adjustable version Preliminary calculations: The ...

  • Page 17

    Application Hints (Continued) Note: These charts assume that the inductor ripple current inductor is approximately 20% to 30% of the average inductor current (when the regulator is under full load). Greater ripple current causes higher peak switch currents and greater ...

  • Page 18

    Application Hints (Continued) Inductor Manufacturer’s Part Number Code Schott Pulse L47 67126980 PE - 53112 L68 67126990 PE - 92114 L100 67127000 PE - 92108 L150 67127010 PE - 53113 L220 67127020 PE - 52626 L330 67127030 PE - 52627 ...

  • Page 19

    Application Hints (Continued) 3. Output Voltage Selection (R1 and R2) This section is for applications using the LM1577-ADJ/ LM2577-ADJ. Skip this section if the LM1577-12/LM2577-12 or LM1577-15/LM2577-15 is being used. With the LM1577-ADJ/LM2577-ADJ, the output voltage is given by V ...

  • Page 20

    Application Hints (Continued) Note: Pin numbers shown are for TO-220 (T) package. FIGURE 13. Step-up Regulator Delivers 12V from a 5V Input FIGURE 14. Line Regulation (Typical) of Step-Up Regulator of Figure 13 A: Output Voltage Change, 100 mV/div. (AC-coupled) ...

  • Page 21

    Application Hints (Continued) FLYBACK REGULATOR A Flyback regulator can produce single or multiple output voltages that are lower or greater than the input supply voltage. Figure 18 shows the LM1577/LM2577 used as a flyback regulator with positive and negative regulated ...

  • Page 22

    Application Hints (Continued Pulse Engineering, PE-65300 D1 1N5821 FIGURE 18. LM1577-ADJ/LM2577-ADJ Flyback Regulator with www.national.com 01146818 ± Outputs 22 ...

  • Page 23

    Application Hints (Continued) Duty Cycle Primary Current Variation Peak Primary Current Switch Voltage when Off Diode Reverse Voltage Average Diode Current Peak Diode Current Short Circuit Diode Current Power Dissipation of LM1577/LM2577 C. Calculate the minimum value ...

  • Page 24

    Application Hints (Continued) step-up regulator, and this requires a larger bypass capacitor to decouple the LM1577/LM2577 V IN most applications, a low ESR, 1.0 µF cap will be sufficient connected very close to the V IN Transformer ...

  • Page 25

    Application Hints (Continued Pulse Engineering, PE-65300 D1 1N5821 FIGURE 22. Flyback Regulator Easily Provides Dual Outputs FIGURE 23. Line Regulation (Typical) of Flyback Regulator of Figure 22, +15V Output A: Output Voltage Change, 100 mV/div B: ...

  • Page 26

    Application Hints (Continued) FIGURE 25. Line Regulation (Typical) of Flyback Regulator of Figure 22, −15V Output A: Switch pin voltage, 20 V/div B: Primary current, 2 A/div C: +15V Secondary current, 1 A/div D: +15V Output ripple voltage, 100 mV/div ...

  • Page 27

    Physical Dimensions inches (millimeters) unless otherwise noted Order Number LM1577K-12/883, LM1577K-15/883, or LM1577K-ADJ/883 Order Number LM2577M-12, LM2577M-15 or LM2577M-ADJ TO-3 Metal Can Package (K) NS Package Number K04A 0.300 Wide SO Package (M) NS Package Number M24B 27 www.national.com ...

  • Page 28

    Physical Dimensions Order Number LM2577N-12, LM2577N-15, or LM2577N-ADJ Order Number LM2577T-12, LM2577T-15, or LM2577T-ADJ www.national.com inches (millimeters) unless otherwise noted (Continued) Molded Dual-In-Line Package (N) NS Package Number N16A TO-220, Straight Leads (T) NS Package Number TO5A 28 ...

  • Page 29

    Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Order Number LM2577T-12 Flow LB03, LM2577T-15 Flow LB03, or LM2577T-ADJ Flow LB03 TO-220, Bent Staggered Leads (T) NS Package Number T05D 29 www.national.com ...

  • Page 30

    Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Order Number LM2577S-12, LM2577S-15 or LM2577S-ADJ 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 ...

  • Page 31

    Tel: 81-3-5639-7560 ...