National Semiconductor LM2673 Technical data

查询LM2673S-12供应商

LM2673 SIMPLE SWITCHER

3A Step-Down Voltage Regulator

with Adjustable Current Limit

LM2673 SIMPLE SWITCHER 3A Step-Down Voltage Regulator with Adjustable Current Limit

October 2003

General Description

The LM2673 series of regulators are monolithic integrated circuits which provide all of the active functions for a stepdown (buck) switching regulator capable of driving up to 3A loads with excellent line and load regulation characteristics. High efficiency ( ON-resistance DMOS power switch. The series consists of fixed output voltages of 3.3V, 5V and 12V and an adjustable output version.

The SIMPLE SWITCHER concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260KHz) allows the use of physically smaller sized components. A family of standard inductors for use with the LM2673 are available from several manufacturers to greatly simplify the design process.

Other features include the ability to reduce the input surge current at power-ON by adding a softstart timing capacitor to gradually turn on the regulator. The LM2673 series also has built in thermal shutdown and resistor programmable current limit of the power MOSFET switch to protect the device and load circuitry under fault conditions. The output voltage is guaranteed to a controlled to within a

90%) is obtained through the use of a low

2% tolerance. The clock frequency is

11% tolerance.

Typical Application

Features

n Efficiency up to 94% n Simple and easy to design with (using off-the-shelf

external components)

n Resistor programmable peak current limit over a range

of 2A to 5A.

n 150 mΩ DMOS output switch n 3.3V, 5V and 12V fixed output and adjustable (1.2V to

37V ) versions

2%maximum output tolerance over full line and load

conditions

n Wide input voltage range: 8V to 40V n 260 KHz fixed frequency internal oscillator n Softstart capability n −40 to +125˚C operating junction temperature range

Applications

n Simple to design, high efficiency (>90%) step-down

switching regulators

n Efficient system pre-regulator for linear voltage

regulators

n Battery chargers

10091303

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

Connection Diagrams and Ordering Information

LM2673

TO-263 Package

Top View

TO-220 Package

Top View

Order Number

LM2673S-3.3, LM2673S-5.0,

LM2673S-12 or LM2673S-ADJ

See NSC Package Number TS7B

See NS package Number SRC14A

10091301

Order Number

10091302

LM2673T-3.3, LM2673T-5.0,

LM2673T-12 or LM2673T-ADJ

See NSC Package Number TA07B

Top View

10091335

LLP-14

Ordering Information for LLP Package

Output Voltage Order Information Package Marking Supplied As

12 LM2673SD-12 S0002SB 250 Units on Tape and Reel

12 LM2673SDX-12 S0002SB 2500 Units on Tape and Reel

3.3 LM2673SD-3.3 S0002TB 250 Units on Tape and Reel

3.3 LM2673SDX-3.3 S0002TB 2500 Units on Tape and Reel

5.0 LM2673SD-5.0 S0002UB 250 Units on Tape and Reel

5.0 LM2673SDX-5.0 S0002UB 2500 Units on Tape and Reel

ADJ LM2673SD-ADJ S0002VB 250 Units on Tape and Reel

ADJ LM2673SDX-ADJ S0002VB 2500 Units on Tape and Reel

www.national.com 2

LM2673

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 Supply Voltage 45V

Storage Temperature Range −65˚C to 150˚C

Soldering Temperature

Wave 4 sec, 260˚C

Infrared 10 sec, 240˚C

Vapor Phase 75 sec, 219˚C

Softstart Pin Voltage −0.1V to 6V

Switch Voltage to Ground −1V to V

Operating Ratings

Boost Pin Voltage VSW+8V

Feedback Pin Voltage −0.3V to 14V

Power Dissipation Internally Limited

Supply Voltage 8V to 40V

Junction Temperature Range (T

) −40˚C to 125˚C

ESD (Note 2) 2 kV

Electrical Characteristics Limits appearing in bold type face apply over the entire junction temperature

range of operation, −40˚C to 125˚C. Specifications appearing in normal type apply for T

A=TJ

= 25˚C. R

ADJ

= 8.2KΩ

LM2673-3.3

Symbol Parameter Conditions Typical Min Max Units

(Note 3) (Note 4) (Note 4)

OUT

η Efficiency V

Output Voltage VIN= 8V to 40V, 100mA ≤ I

= 12V, I

=3A 86 %

LOAD

≤ 3A 3.3 3.234/3.201 3.366/3.399 V

OUT

LM2673-5.0

Symbol Parameter Conditions Typical Min Max Units

(Note 3) (Note 4) (Note 4)

OUT

η Efficiency V

Output Voltage VIN= 8V to 40V, 100mA ≤ I

= 12V, I

=3A 88 %

LOAD

≤ 3A 5.0 4.900/4.850 5.100/5.150 V

OUT

LM2673-12

Symbol Parameter Conditions Typical Min Max Units

(Note 3) (Note 4) (Note 4)

OUT

η Efficiency V

Output Voltage VIN= 15V to 40V, 100mA ≤ I

= 24V, I

=3A 94 %

LOAD

≤ 3A 12 11.76/11.64 12.24/12.36 V

OUT

LM2673-ADJ

Symbol Parameter Conditions Typ Min Max Units

(Note 3) (Note 4) (Note 4)

η Efficiency V

Feedback Voltage

VIN= 8V to 40V, 100mA ≤ I

Programmed for 5V

OUT

= 12V, I

=3A 88 %

LOAD

OUT

≤ 3A

1.21 1.186/1.174 1.234/1.246 V

www.national.com3

All Output Voltage Versions Electrical Characteristics

LM2673

Limits appearing in bold type face apply over the entire junction temperature range of operation, −40˚C to 125˚C. Specifications appearing in normal type apply for T and Adjustable versions and V

=24V for the 12V version.

= 25˚C. Unless otherwise specified, R

A=TJ

Symbol Parameter Conditions Typ Min Max Units

DEVICE PARAMETERS

Quiescent

FEEDBACK

= 8V 4.2 6 mA

Current

For 3.3V, 5.0V, and ADJ Versions

FEEDBACK

= 15V

For 12V Versions

ADJ

DS(ON)

Current Limit Adjust Voltage

Current Limit R

Output Leakage Current

Switch

1.21 1.181/1.169 1.229/1.246 V

= 8.2KΩ, (Note 5) 4.5 3.8/3.6 5.25/5.4 A

ADJ

VIN= 40V, Softstart Pin = 0V V

SWITCH

=0V = −1V

= 3A 0.15 0.17/0.29 Ω

1.0 6

On-Resistance

Oscillator

Measured at Switch Pin 260 225 280 kHz

Frequency

D Duty Cycle Maximum Duty Cycle 91 %

Minimum Duty Cycle 0 %

BIAS

SFST

Feedback Bias Current

Softstart Threshold

FEEDBACK

= 1.3V

ADJ Version Only

85 nA

0.63 0.53 0.74 V

Voltage

SFST

Softstart Pin Current

Thermal Resistance

Softstart Pin = 0V

3.7 6.9 µA

T Package, Junction to Ambient 65

(Note 6)

T Package, Junction to Ambient 45

(Note 7)

T Package, Junction to Case 2

S Package, Junction to Ambient 56 ˚C/W

(Note 8)

S Package, Junction to Ambient 35

(Note 9)

S Package, Junction to Ambient 26

(Note 10)

S Package, Junction to Case 2 ++

SD Package, Junction to Ambient 55

(Note 11)

SD Package, Junction to Ambient 29

(Note 12)

= 8.2KΩ,VIN=12V for the 3.3V, 5V

ADJ

1.5 15

mA mA

˚C/W

www.national.com 4

All Output Voltage Versions Electrical Characteristics

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

guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test condition, see the electrical Characteristics tables.

Note 2: ESD was applied using the human-body model, a 100pF capacitor discharged through a 1.5 kΩ resistor into each pin.

Note 3: Typical values are determined with T

Note 4: All limits are guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100%

tested during production with T methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).

Note 5: The peak switch current limit is determined by the following relationship: I

Note 6: Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with

board with minimum copper area.

Note 7: Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with containing approximately 4 square inches of (1 oz.) copper area surrounding the leads.

Note 8: Junction to ambient thermal resistance for the 7 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 9: Junction to ambient thermal resistance for the 7 lead TO-263 mounted horizontally against a PC board area of 0.4896 square inches (3.6 times the area of the TO-263 package) of 1 oz. (0.0014 in. thick) copper.

Note 10: Junction to ambient thermal resistance for the 7 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

Note 11: Junction to ambient thermal resistance for the 14-lead LLP mounted on a PC board copper area equal to the die attach paddle.

Note 12: Junction to ambient thermal resistance for the 14-lead LLP mounted on a PC board copper area using 12 vias to a second layer of copper equal to die

attach paddle. Additional copper area will reduce thermal resistance further. For layout recommendations, refer to Application Note AN-1187.

software.

A=TJ

= 25˚C. All limits at temperature extremes are guaranteed via correlation using standard standard Quality Control (SQC)

(Continued)

= 25˚C and represent the most likely norm.

=37,125/ R

ADJ

⁄2inch leads in a socket, or on a PC

⁄2inch leads soldered to a PC board

LM2673

www.national.com5

Typical Performance Characteristics

LM2673

Normalized

Output Voltage Line Regulation

10091304

Efficiency vs Input Voltage Efficiency vs I

10091306 10091307

LOAD

Switch Current Limit Operating Quiescent Current

10091305

10091308 10091309

www.national.com 6

Typical Performance Characteristics (Continued)

Switching Frequency Feedback Pin Bias Current

LM2673

Load Transient Response for Continuous Mode

= 20V, V

L = 33 µH, C

A: Output Voltage, 100 mV//div, AC-Coupled.

B: Load Current: 500 mA to 3A Load Pulse

= 200 µF, C

OUT

=5V

ESR=26mΩ

OUT

10091317

Horizontal Time Base: 100 µs/div

Continuous Mode Switching Waveforms

= 20V, V

L = 33 µH, C

OUT

= 5V, I

OUT

= 200 µF, C

=3A

LOAD

ESR=26mΩ

OUT

10091312

10091313

Load Transient Response for Discontinuous Mode

= 20V, V

L = 10 µH, C

A: Output Voltage, 100 mV/div, AC-Coupled.

B: Load Current: 200 mA to 3A Load Pulse

= 400 µF, C

OUT

= 5V,

ESR=13mΩ

OUT

10091318

Horizontal Time Base: 200 µs/div

Discontinuous Mode Switching Waveforms

= 20V, V

L = 10 µH, C

OUT

= 5V, I

OUT

= 400 µF, C

= 500 mA

LOAD

ESR=13mΩ

OUT

A: VSWPin Voltage, 10 V/div.

B: Inductor Current, 1 A/div

C: Output Ripple Voltage, 20 mV/div AC-Coupled

Horizontal Time Base: 1 µs/div

10091315

10091316

A: VSWPin Voltage, 10 V/div.

B: Inductor Current, 1 A/div

C: Output Ripple Voltage, 20 mV/div AC-Coupled

Horizontal Time Base: 1 µs//iv

www.national.com7

Block Diagram

LM2673

* Active Inductor Patent Number 5,514,947

†

Active Capacitor Patent Number 5,382,918

10091314

www.national.com 8

+ 18 hidden pages