GBPC3504 - LITE-ON ELECTRONICS - searchdatasheet.com

LM2575

52kHz Simple 1A Buck Regulator

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

May 2009 1 M9999-051209-B

General Description

The LM2575 series of monolithic integrated circuits

provide all the active functions for a step-down (buck)

switching regulator. Fixed versions are available with a

3.3V, 5V, 12V, fixed output. Adjustable versions have an

output voltage range from 1.23V to 37V. Both versions are

capable of driving a 1A load with excellent line and load

regulation.

These regulators are simple to use because they require a

minimum number of external components and include

internal frequency compensation and a fixed-frequency

oscillator.

The LM2575 series offers a high efficiency replacement for

popular three-terminal adjustable linear regulators. It

substantially reduces the size of the heat sink, and in

many cases no heat sink is required.

A standard series of inductors available from several

different manufacturers are ideal for use with the LM2575

series. This feature greatly simplifies the design of switch-

mode power supplies.

The feedback voltage is guaranteed to ±2% tolerance for

adjustable versions, and the output voltage is guaranteed

to ±3% for fixed versions, within specified input voltages

and output load conditions. The oscillator frequency is

guaranteed to ±10%. External shutdown is included,

featuring less than 200µA standby current. The output

switch includes cycle-by-cycle current limiting and thermal

shutdown for full protection under fault conditions.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Features

• 3.3V, 5V, 12V, and adjustable output versions

• Voltage over specified line and load conditions:

– Fixed version: ±3% max. output voltage

– Adjustable version: ±2% max. feedback voltage

• Guaranteed 1A output current

• Wide input voltage range

– 4V to 40V

• Wide output voltage range

– 1.23V to 37V

• Requires only 4 external components

• 52kHz fixed frequency internal oscillator

• Low power standby mode IQ typically <200µA

• 80% efficiency (adjustable version typically >80%)

• Uses readily available standard inductors

• Thermal shutdown and current limit protection

• 100% electrical thermal limit burn-in

Applications

• Simple high-efficiency step-down (buck) regulator

• Efficient pre-regulator for linear regulators

• On-card switching regulators

• Positive to negative converter (inverting Buck-Boost)

• Isolated flyback converter using minimum number of

external components

• Negative boost converter

___________________________________________________________________________________________________________

Typical Applications

7V–40V

Unregulated

DC Input LM2575-5.0

CIN

100µF

+VIN

Gnd

On/Off

Output

4Feedback

330µH +

1N5822

COUT

330µF

+5V, 1A

Regulated

Output

Note: Pin numbers are for TO-220 Package R2

7V–40V

Unregulated

DC Input LM2575

CIN

100µF

+VIN

Gnd

On/Off

Output

4Feedback

330µH +

1N5822

COUT

330µF

R2 3.09k

R1 1k

VOUT = 1.23 1 +

()

+5V, 1A

Regulated

Output

Note: Pin numbers are for TO-220 Package

Fixed Regulation in Typical Application Adjustable Regulation in Fixed Output Application

Micrel, Inc. LM2575

May 2009 2 M9999-051209-B

Ordering Information

Part Number

Standard Pb-Free /

RoHS Compliant Temperature Range Package

LM2575BN* Contact Factory –40° to +85°C 16-Pin Plastic DIP

LM2575-3.3BN Contact Factory –40° to +85°C 16-Pin Plastic DIP

LM2575-5.0BN LM2575-5.0YN –40° to +85°C 16-Pin Plastic DIP

LM2575-12BN LM2575-12YN –40° to +85°C 16-Pin Plastic DIP

LM2575BWM* LM2575YWM* –40° to +85°C 24-Pin Wide SOIC

LM2575-3.3BWM LM2575-3.3YWM –40° to +85°C 24-Pin Wide SOIC

LM2575-5.0BWM LM2575-5.0YWM –40° to +85°C 24-Pin Wide SOIC

LM2575-12BWM LM2575-12YWM –40° to +85°C 24-Pin Wide SOIC

LM2575BT*† LM2575WT*/** –40° to +85°C 5-Pin TO-220

LM2575-3.3BT† LM2575-3.3WT** –40° to +85°C 5-Pin TO-220

LM2575-5.0BT† LM2575-5.0WT** –40° to +85°C 5-Pin TO-220

LM2575-12BT† LM2575-12WT** –40° to +85°C 5-Pin TO-220

LM2575BU* LM2575WU*/** –40° to +85°C 5-Pin TO-263

LM2575-3.3BU LM2575-3.3WU** –40° to +85°C 5-Pin TO-263

LM2575-5.0BU LM2575-5.0WU** –40° to +85°C 5-Pin TO-263

LM2575-12BU LM2575-12WU** –40° to +85°C 5-Pin TO-263

Notes:

* Adjustable output regulators.

** RoHS compliant with "high-melting solder" exemption.

† Contact factory for bent or staggered leads option.

Micrel, Inc. LM2575

May 2009 3 M9999-051209-B

Pin Configur ation

TAB

3 GND

4FB

5 ON/OF

2 OUT

1 VIN

TAB

5 ON/OF

4FB

3 GND

2 OUT

1 VIN

5-Pin TO-220 (T) 5-Pin TO-263 (U)

1NC

OUT

GND

16 VIN

GND

ON/OFF

8 PWR GND NC1312

NC VIN1411

1PWR GND

SIG GND

ON/OFF

24 NC

OUT

VIN

16-Pin Plastic DIP (N) 24-Pin Wide SOIC (WM)

Micrel, Inc. LM2575

May 2009 4 M9999-051209-B

Absolute Maximum Ratings(1)

Maximum Supply Voltage (VIN) ......................................45V

ON/OFF Pin Input Voltage. ......................–0.3V ≤ V ≤ +40V

Output Voltage to Ground (Steady State) ......................–1V

Power Dissipation .....................................Internally Limited

Maximum Junction Temperature................................ 150°C

Lead Temperature (soldering, 10 sec.)...................... 260°C

Storage Temperature (Ts) .........................–65°C to +150°C

Minimum ESD Rating

C = 100pF, R = 1.5kΩ.............................................. 2kV

FB Pin ...................................................................... 1kV

Operating Ratings

Supply Voltage (VIN).......................................................40V

Junction Temperature Range (TJ).......–40°C ≤ TJ ≤ +125°C

Electrical Characteristics

Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply over full Operating

Temperature Range. Unless otherwise specified, VIN = 12V, and ILOAD = 200mA.

Symbol Parameter Condition Typ

LM2575

Limit

(Note 2) Units

(Limits)

SYSTEM PARAMETERS, ADJUSTABLE REGULATORS (Note 3) Test Circuit Figure 1

Feedback Voltage VIN = 12V , ILOAD = 0.2A

VOUT = 5V

1.230

1.217

1.243

V(min)

V(max)

VOUT Feedback Voltage LM2575 0.2A ≤ ILOAD ≤ 1A, 8V ≤ VIN ≤ 40V

VOUT = 5V

1.230

1.193/1.180

1.267/1.280

V(min)

V(max)

η Efficiency VIN = 12V, ILOAD = 1A, VOUT = 5V 82 %

SYSTEM PARAMETERS, 3.3V REGULATORS (Note 3) Test Circuit Figure 1

Output Voltage VIN = 12V , ILOAD = 0.2A

VOUT = 3.3V

3.3

3.234

3.366

V(min)

V(max)

VOUT Output Voltage LM2575-3.3 0.2A ≤ ILOAD ≤ 1A, 8V ≤ VIN ≤ 40V

VOUT = 3.3V

3.3

3.168/3.135

3.432/3.465

V(min)

V(max)

η Efficiency VIN = 12V, ILOAD = 1A 75 %

SYSTEM PARAMETERS, 5V REGULATORS (Note 3) Test Circuit Figure 1

Output Voltage VIN = 12V , ILOAD = 0.2A

VOUT = 5V

5.0

4.900

5.100

V(min)

V(max)

VOUT Output Voltage LM2575-5.0 0.2A ≤ ILOAD ≤ 1A, 8V ≤ VIN ≤ 40V

VOUT = 5V

5.0

4.800/4.750

5.200/5.250

V(min)

V(max)

η Efficiency VIN = 12V, ILOAD = 1A 82 %

SYSTEM PARAMETERS, 12V REGULATORS (Note 3) Test Circuit Figure 1

Output Voltage VIN = 25V , ILOAD = 0.2A

VOUT = 12V

11.760

12.240

V(min)

V(max)

VOUT Output Voltage LM2575-12 0.2A ≤ ILOAD ≤ 1A, 15V ≤ VIN ≤ 40V

VOUT = 12V

11.520/11.400

12.480/12.600

V(min)

V(max)

η Efficiency VIN = 25V, ILOAD = 1A 88 %

Micrel, Inc. LM2575

May 2009 5 M9999-051209-B

Symbol Parameter Condition Typ

LM2575

Limit

(Note 2) Units

(Limits)

DEVICE PARAMETERS, ADJUSTABLE REGULATOR

IB Feedback Bias Current VOUT = 5V 50 100/500 nA

DEVICE PARAMETERS, FIXED and ADJUSTABLE REGULATORS

fO Oscillator Frequency 52

47/42

58/63

kHz

kHz(min)

kHz(max)

VSAT Saturation Voltage IOUT = 1A (Note 4) 0.9

1.2/1.4

V(max)

DC Max Duty Cycle (ON) (Note 5) 98

%(max)

ICL Current Limit Peak Current, tON ≤ 3µs (Note 4) 2.2

1.7/1.3

3.0/3.2

A(min)

A(max)

IL Output Leakage Current VIN = 40V, (Note 6), Output = 0V

Output = –1V

(Note 6) Output = –1V

mA(max)

IQ Quiescent Current (Note 6) 5

mA(max)

ISTBY Standby Quiescent Current ON/OFF Pin = 5V (OFF) 50

200

µA

µA(max)

θJA T Package, Junction to Ambient (Note 7) 65

θJA T Package, Junction to Ambient (Note 8) 45

θJC T Package, Junction to Case 2

θJA N Package, Junction to Ambient (Note 9) 85

θJA

Thermal Resistance

WM Package, Junction to Ambient (Note 9) 100

°C/W

ON/OFF CONTROL, FIXED and ADJUSTABLE REGULATORS Test Circuit Figure 1

VIH

VIL

ON/OFF Pin Logic

Input Level

VOUT = 0V

VOUT = 5V

1.4

1.2

2.2/2.4

1.0/0.8

V(min)

V(max)

IIH ON /OFF Pin = 5V (OFF) 4

µA

µA(max)

IIL

ON/OFF Pin Logic

Current

ON /OFF Pin = 0V (ON) 0.01

µA

µA(max)

Notes:

1. Absolute Maximum Rating indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device

is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical

Characteristics.

2. All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are100%

production tested. All limits at temperature extreme are guaranteed via testing.

3. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the

LM2575/LM1575 is used as shown in Figure 1 test circuit, system performance will be shown in system parameters section of Electrical

Characteristics.

4. Output (pin 2) sourcing current. No diode, inductor or capacitor connected to output.

5. Feedback (pin 4) removed from output and connected to 0V.

6. Feedback (pin 4) removed from output and connected to 12V to force the output transistor OFF.

7. Junction to ambient thermal resistance (no external heat sink) for the 5-pin TO-220 package mounted vertically, with 1/2" leads in a socket, or on PC

board with minimum copper area.

8. Junction to ambient thermal resistance (no external heat sink) for the 5-pin TO-220 package mounted vertically, with 1/4" leads soldered to PC

board containing approximately 4 square inches of copper area surrounding the leads.

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

thermal resistance further.

Micrel, Inc. LM2575

May 2009 6 M9999-051209-B

Test Circuits and Layout Guidelines

LM2575

+100µF

+VIN

3GND 5ON/OFF 2

OUTPUT

FEEDBACK

330µH +

MBR360

COUT

470µF

VOUT

5.00V

7V - 40V

UNREGULATED

DC INPUT CIN

CIN

— 100µF, 75V Aluminum Electrolytic

COUT

— 470µF, 15V Aluminum Electrolytic

D1 — Schottky, MBR360

L1 — 330µH, 415-0926 (AIE)

R1 — 1k, 0.01%

R2 — 3.065k, 0.01%

5-pin TO-220 socket—2936 (Loranger Mfg. Co.)

4-pin TO-3 socket—8112-AG7 (Augat Inc.)

LM2575-5.0

+100µF

+VIN

3GND 5ON/OFF 2

OUTPUT

FEEDBACK

330µH +

MBR360

COUT

220µF

VOUT

5.00V

Note: Pin numbers are for TO-220 Package

7V - 40V

UNREGULATED

DC INPUT CIN

CIN — 100µF, 75V Aluminum Electrolytic

COUT— 330µF, 15V Aluminum Electrolytic

D1 — Schottky,MBR360

L1 — 330µH, 415-0926 (AIE)

5-pin TO-220 socket — 2936 (Loranger Mfg. Co.)

4-pin TO-3 socket — 8112-AG7 (Augat Inc.)

Figure 1.

As in any switching regulator, layout is very important.

Rapidly switching currents associated with wiring

inductance generate voltage transient switch can cause

problems. For minimal stray inductance and ground

loops, the length of the leads indicated by heavy lines

should be kept as short as possible. Single-point

grounding (as indicated) or ground plane construction

should be used for best results.

Micrel, Inc. LM2575

May 2009 7 M9999-051209-B

Typical Characteristics (circuit of Figure 1 )

Supply Curre nt

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

20 Measured at

Ground Pin

OUT

= 5V

40 102030405060

ILOAD

to 1A

Supply Curre nt

vs. Duty Cycle

DUTY CYCLE (%)

20.0

17.5

15.0

12.5

10.0

7.5

5.0

2.0

0020406080100

VIN from 7V to 40V

ILOAD

= 200 mA

SUPPLY CURRENT (mA)

200

150

100

-75

VIN

= 12V

STANDBY QUIESCENT CURRENT (µA)

Standb

Quiescent Current

VIN

= 40V

-50 -25 0 25 50 75 100 125150

Curre nt Limi t

-75

VIN = 25V

OUTPUT CURRENT (A)

INPUT VOLTAGE (V)

100

EFFICIENCY (%)

Efficiency

VOUT

= 12V

-50 -25 0 25 50 75 100125 150

200 mA

VOUT

= 3V

0 5 10 15 20 25 30 35 40

Minimum Operating

Voltage

5.0

ILOAD

= 200 mA

INPUT VOLTAGE (V)

Line R e gulati on

INPUT VOLTAGE (V)

NORMALIZED FEEDBACK VOLTAGE (mV)

100

-100

-75

STANDBY QUIESCENT CURRENT (µA)

Feedback Pin Current

-50 -25 0 25 50 75 100 125150

VOUT

= 1.23V

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

-75 -50 -25 0 25 50 75 100125150

-2

-4

-6

5 1015202530

-25

-50

-75

-8

-75

NORMALIZED FREQUENCY (%)

Oscillator Frequency

-50 -25 0 25 50 75 100125150

-2

-4

--6 VIN = 12V

VIN = 40V

Normalized at 25C

Normalized toVIN

= 10V

VOUT = 5V

ILOAD = 500mA

TJ = 25

ON/OFF

= 5V

Switch

Satura tio n Volta ge

SWITCH CURRENT (A)

1.2

-55 C

1.0

0.8

0.6

0.4

SATURATION VOLTAGE (V)

0.20.40.60.81.0

25 C

125 C

150 C

-40 C

Dropout Vol ta ge

INPUT-OUTPUT DIFFERENTIAL (V)

2.0

-75 -50 -25 0 25 50 75 100125150

OUT = 5%

RIND = 0.2

ILOAD

= 1A

ILOAD

= 200 mA

1.5

1.0

0.5

Normalized

Output Voltage

OUTPUT VOLTAGE CHANGE (mV

)

100

-25

-50

-75

-100

-75 -50 -25 0 25 50 75 100125150

VIN = 12V

ILOAD = 200mA

Normalized toT

J = 25 C

Micrel, Inc. LM2575

May 2009 8 M9999-051209-B

Typical Characteristics (continued)

Normalize

Feedback Voltage*

NORMALIZED FEEDBACK VOLTAGE (mV)

-5

-10

-15

-20

-25

-75 -50 -25 0 25 50 75 100125150

VIN

= 12V

ILOAD

= 200mA

Normalized toT

J= 25 C

Feedback Voltag

vs Duty Cycle*

DUTY CYCLE (%)

FEEDBACK VOLTAGE CHANGE (mV)

-5

-10

-15

-20

ILOAD = 200 mA

VIN = 40V

VIN = 7V

020406080100

* Adjustable version only

Micrel, Inc. LM2575

May 2009 9 M9999-051209-B

Functional Characteristics (circuit of Figure 1)

Load Transient Response

100µs/div.

+100mV

–100mV

Output

Voltage

Change

1.0A

0.5A

Output

Current

VOUT = 5V

Switching Waveforms

10V

.5A

A: Output pin voltage 10V/div

B: Output pin current 1A/div

C: Inductor current 0.5A/div

D: Output ripple voltage 20 mV/div. AC coupled

Horizontal Time Base: 5µs/div

VOUT = 5V VIN = 20V

Functional Diagrams

ON/OFF

COMPARATOR

FIXED GAIN

ERROR AMP

1 AMP

SWITCH

OUT

DRIVER

VIN

1.23V

BAND-GAP

REFERENCE

52 kHz

OSCILLATOR RESET THERMAL

SHUTDOWN

CURRENT

LIMIT

Note: Pin numbers are for the TO-220 package

INTERNAL

REGULATOR ON/OFF

GND

3.1k

1.0k

Fixed Regulator

ON/OFF

COMPARATOR

FIXED GAIN

ERROR AMP

1 AMP

SWITCH

OUT

DRIVER

1.23V

BAND-GAP

REFERENCE

52 kHz

OSCILLATOR RESET THERMAL

SHUTDOWN

CURRENT

LIMIT

INTERNAL

REGULATOR ON/OFF

GND

Adjustable Regulator

Micrel, Inc. LM2575

May 2009 10 M9999-051209-B

Package Information

0.020

(0.508)

0.018±0.003

(0.457±0.076)

PIN 1

0.780

(19.812)

.250±0.005

(6.350±0.127)

0.025±0.015

(0.635±0.381)

0.100±0.010

(2.540±0.254)

MAX

0.030-0.110

(0.762-2.794) RAD

0.125

(3.175) MIN

0.020

(0.508) MIN

0.130±0.005

(3.302±0.127)

+0.025

–0.015

+0.635

–0.381

0.325

8.255

()

0.009-0.015

(0.229-0.381)

0-10

0.290-0.320

(7.336-8.128)

0.040

(1.016)TYP

16-Pin Plastic DIP (N)

24-Pin Wide SOIC (WM)

Micrel, Inc. LM2575

May 2009 11 M9999-051209-B

5-Pin TO-220 (T)

5-Pin TO-263 (T)

Micrel, Inc. LM2575

May 2009 12 M9999-051209-B

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com

The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its

use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product

can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant

into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A

Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully

indemnify Micrel for any damages resulting from such use or sale.