Texas Instruments LM3674MF, LM3674MF-1.2, LM3674MF-1.5, LM3674MF-1.8, LM3674MF-1.875 Schematic [ru]

1

2

5

4

3

V

IN

SW

FB

EN

GND

L1:2.2 PH

V

OUT

C

OUT

10 PF

C

IN

4.7 PF

LM3674

V

IN

2.7V to 5.5V

LM3674

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LM3674 2MHz, 600mA Step-Down DC-DC Converter in SOT-23

Check for Samples: LM3674

1

FEATURES

2

• 600mA Max Load Current

• Input Voltage Range from 2.7V to 5.5V

• Available in Fixed and Adjustable Output
Voltages Ranging from 1.0V to 3.3V

• Operates from a Single Li-Ion Cell Battery

• Internal Synchronous Rectification for High
Efficiency

• Internal Soft Start

• 0.01 µA Typical Shutdown Current

• 2 MHz PWM Fixed Switching Frequency (typ)

• 5-Pin SOT-23 Package

• Current Overload Protection and Thermal
Shutdown Protection

APPLICATIONS

• Mobile Phones

• PDAs

• MP3 Players

• Portable Instruments

• W-LAN

• Digital Still Cameras

• Portable Hard Disk Drives

SNVS405F –DECEMBER 2005–REVISED MAY 2013

DESCRIPTION

The LM3674 step-down DC-DC converter is
optimized for powering low voltage circuits from a
single Li-Ion cell battery and input voltage rails from

2.7V to 5.5V. It provides up to 600mA load current,
over the entire input voltage range. There are several
fixed output voltages and adjustable output voltage
versions.

The device offers superior features and performance
for mobile phones and similar portable systems.
During PWM mode, the device operates at a fixed­frequency of 2 MHz (typ). Internal synchronous
rectification provides high efficiency during Pulse
Width Modulation (PWM) mode operation. In
shutdown mode, the device turns off and reduces
battery consumption to 0.01 µA (typ).

The LM3674 is available in a 5-pin SOT-23 package
in leaded (PB) and lead-free (NO PB) versions. A
high switching frequency of 2 MHz (typ) allows use of
only three tiny external surface-mount components,
an inductor and two ceramic capacitors.

TYPICAL APPLICATION CIRCUITS

Figure 1. Typical Application Circuit

1

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

Copyright © 2005–2013, Texas Instruments Incorporated

V

IN

1

GND

2

EN

3

FB

4

SW

5

1

2

5

43

V

IN

SW

FB

EN

GND

L1: 2.2 PH

V

OUT

C

OUT

: 10 PF

CIN: 4.7 PF

LM3674-

ADJ

V

IN

2.7V to 5.5V

C

1

C

2

R

1

R

2

LM3674

SNVS405F –DECEMBER 2005–REVISED MAY 2013

Figure 2. Typical Application Circuit for Adjustable Voltage Option

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PIN DIAGRAM

Figure 3. Top View

5-Pin SOT-23 Package

See Package Number DBV0005A

Note: The actual physical placement of the package marking will vary from part to part.

PIN DESCRIPTIONS

Pin Number Name Description

1 V

IN

2 GND Ground pin.
3 EN

4 FB version external resistor dividers are required ( Figure 2). The internal resistor dividers are disabled for

5 SW Switching node connection to the internal PFET switch and NFET synchronous rectifier.

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Power supply input. Connect to the input filter capacitor ( Figure 1).

Enable input. The device is in shutdown mode when voltage to this pin is <0.4V and enable when
>1.0V. Do not leave this pin floating.

Feedback analog input. Connect to the output filter capacitor for fixed voltage versions. For adjustable
the adjustable version.

Product Folder Links: LM3674

LM3674

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These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.

ORDERING INFORMATION

LM3674 (5 Pin SOT-23)

Ordering Information Voltage Option (V)

LM3674MF-1.2
LM3674MFX-1.2
LM3674MF-1.2/NOPB
LM3674MFX-1.2/NOPB
LM3674MF-1.5
LM3674MFX-1.5
LM3674MF-1.5/NOPB
LM3674MFX-1.5/NOPB
LM3674MF-1.6
LM3674MFX-1.6
LM3674MF-1.6/NOPB
LM3674MFX-1.6/NOPB
LM3674MF-1.8
LM3674MFX-1.8
LM3674MF-1.8/NOPB
LM3674MFX-1.8/NOPB
LM3674MF-1.875
LM3674MFX-1.875
LM3674MF-1.875/NOPB
LM3674MFX-1.875/NOPB
LM3674MF-2.8
LM3674MFX-2.8
LM3674MF-2.8/NOPB
LM3674MFX-2.8/NOPB
LM3674MF-ADJ
LM3674MFX-ADJ
LM3674MF-ADJ/NOPB
LM3674MFX-ADJ/NOPB

(1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI

web site at www.ti.com.

(2) Package drawings, thermal data, and symbolization are available at www.ti.com/packaging.

SNVS405F –DECEMBER 2005–REVISED MAY 2013

(1)(2)

1.2

1.5

1.6

1.8

1.875

2.8

Adjustable

Copyright © 2005–2013, Texas Instruments Incorporated Submit Documentation Feedback 3

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LM3674

SNVS405F –DECEMBER 2005–REVISED MAY 2013

Absolute Maximum Ratings

(1)(2)

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VINPin: Voltage to GND −0.2V to 6.0V
EN, FB, SW Pin: (GND−0.2V) to

(VIN+ 0.2V)
Continuous Power Dissipation
Junction Temperature (T

(3)

) +125°C

J-MAX

Internally Limited

Storage Temperature Range −65°C to +150°C
Maximum Lead Temperature 260°C

(Soldering, 10 sec.)
ESD Rating

(4)

2 kV

Human Body model: All Pins
Machine Model: All Pins 200V

(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings are conditions under

which operation of the device is ensured. Operating Ratings may not imply performance limits. For performance limits and associated

test conditions, see the Electrical Characteristics tables.
(2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/Distributors for availability and specifications.
(3) In Applications where high power dissipation and /or poor package resistance is present, the maximum ambient temperature may have

to be derated. Maximum ambient temperature (T

maximum power dissipation of the device in the application (P

in the application, as given by the following equation: T

at different ambient temperatures.

) is dependent on the maximum operating junction temperature (T

A-MAX

A-MAX

) and the junction to ambient thermal resistance of the package (θJA)

D-MAX

= T

J-MAX

- (θJAx P

). Refer to Dissipation ration table for P

D-MAX

J-MAX

D-MAX

), the

values

(4) The Human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF

capacitor discharged directly into each pin (MIL-STD-883 3015.7). National Semiconductor recommends that all intergrated circuits be

handled with appropriate precautions. Failure to observe proper ESD handling techniques can result in damage.

(4)

(1)(2)(3)

2.7V to 5.5V

Operating Ratings

Input Voltage Range
Recommended Load Current 0A to 600 mA
Junction Temperature (TJ) Range −30°C to +125°C
Ambient Temperature (TA) Range −30°C to +85°C

(1) In Applications where high power dissipation and /or poor package resistance is present, the maximum ambient temperature may have

to be derated. Maximum ambient temperature (T

maximum power dissipation of the device in the application (P

in the application, as given by the following equation: T

at different ambient temperatures.

) is dependent on the maximum operating junction temperature (T

A-MAX

A-MAX

) and the junction to ambient thermal resistance of the package (θJA)

D-MAX

= T

J-MAX

- (θJAx P

). Refer to Dissipation ration table for P

D-MAX

J-MAX

D-MAX

), the

values

(2) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings are conditions under

which operation of the device is ensured. Operating Ratings may not imply performance limits. For performance limits and associated

test conditions, see the Electrical Characteristics tables.
(3) All voltages are with respect to the potential at the GND pin.
(4) Input voltage range recommended for ideal applications performance for the specified output voltages are given below

VIN= 2.7V to 5.5V for 1.0V ≤ V

VIN= ( V

OUT

+ V

DROP OUT

Thermal Properties

) to 5.5V for 1.8 ≤ V

(1)

OUT

< 1.8V

≤ 3.3V Where V

OUT

DROP OUT

= I

LOAD

* (R

DSON (P)

+ R

INDUCTOR

)

over operating free-air temperature range (unless otherwise noted)

Junction-to-Ambient Thermal Resistance (θJA) (SOT-23) for a 2 layer board
Junction-to-Ambient Thermal Resistance (θJA) (SOT-23) for a 4 layer board

(1) Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ= 150°C (typ.) and

disengages at TJ= 130°C
(2) Junction to ambient thermal resistance (θJA) is highly application and board layout dependent. In applications where high power

dissipation exists, special care must be given to thermal dissipation issues in board design. Value specified here 250°C/W is based on

measurement results using a 2 layer, 4" X 3", 2 oz. Cu board as per JEDEC standards. The θJAis 130°C/W if a 4 layer, 4" X 3", 2/1/1/2

oz. Cu board as per JEDEC standards is used.

(2)
(2)

250°C/W
130°C/W

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Product Folder Links: LM3674

LM3674

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Electrical Characteristics

(1)(2)(3)

SNVS405F –DECEMBER 2005–REVISED MAY 2013

Limits in standard typeface are for TJ= 25°C. Limits in boldface type apply over the full operating junction temperature range
(−30°C ≤ TJ≤ 125°C). Unless otherwise noted, specifications apply to the LM3674 with VIN= EN = 3.6V

Parameter Test Condition Min Typ Max Units

V

FB

Feedback Voltage
Line Regulation 2.7V ≤ VIN≤ 5.5V 0.083 %/V

Load Regulation 100 mA ≤ IO≤ 600 mA 0.0010 %/mA

V

REF

I

SHDN

I

Q

R

DSON (P)

R

DSON (N)

I

LIM

V

IH

V

IL

I

EN

F

OSC

Internal Reference Voltage See
Shutdown Supply Current EN = 0V 0.01 1 µA
DC Bias Current into V

Pin-Pin Resistance for PFET ISW= 200mA 380 500 mΩ
Pin-Pin Resistance for NFET ISW= 200mA 250 400 mΩ
Switch Peak Current Limit Open Loop
Logic High Input 1.0 V
Logic Low Input 0.4 V
Enable (EN) Input Current 0.01 1 µA
Internal Oscillator Frequency PWM Mode 1.6 2 2.6 MHz

(1) All voltages are with respect to the potential at the GND pin.
(2) Min and Max limits are specified by design, test or statistical analysis. Typical numbers represent the most likely norm.
(3) The parameters in the electrical characteristic table are tested at VIN= 3.6V unless otherwise specified. For performance over the input

voltage range refer to datasheet curves.
(4) ADJ configured to 1.5V output.
(5) For V
(6) For the ADJ version the resistor dividers should be selected such that at the desired output voltage, the voltage at the FB pin is 0.5V.

less than 2.5V, VIN= 3.6V, for V

OUT

(7) Refer to datasheet curves for closed loop data and its variation with regards to supply voltage and temperature. Electrical Characteristic

table reflects open loop data (FB=0V and current drawn from SW pin ramped up until cycle by cycle current limit is activated). Closed

loop current limit is the peak inductor current measured in the application circuit by increasing output current until output voltage drops

by 10%.

(4)(5)

IO= 10mA -4 +4 %

IO= 100 mA

VIN= 3.6V

(6)

IN

No load, device is not switching 300 600 µA
(FB=0V)

(7)

greater than or equal to 2.5V, VIN= V

OUT

OUT

830 1020 1200 mA

+1.

0.5 V

Dissipation Rating

over operating free-air temperature range (unless otherwise noted)

θ

JA

250°C/W (2 layer board) 400mW 260mW 160mW
130°C/W (4 layer board) 770mW 500mW 310mW

TA≤ 25°C (Power Rating) TA= 60°C (Power Rating) TA= 85°C (Power Rating)

Copyright © 2005–2013, Texas Instruments Incorporated Submit Documentation Feedback 5

Product Folder Links: LM3674

+

-

2 MHz

Oscillator

Soft

Start

Ramp

Generator

+

-

Thermal

Shutdown

Undervoltage

Lockout

V

REF

+

-

0.5V

Error

Amp

Control Logic Driver

Current Limit

Comparator

Ref1

SW

FB

EN

V

IN

PWM Comparator

GND

Bandgap

+

-

Vcomp

1.0V

Frequency

Compensation

Adjustable Version

Fixed Version

LM3674

SNVS405F –DECEMBER 2005–REVISED MAY 2013

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Block Diagram

Figure 4. Simplified Functional Block Diagram

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Product Folder Links: LM3674

-10 10 30 50 70 90
TEMPERATURE (°C)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

SHUTDOWN CURRENT (

PA)

-30

EN = GND

VIN = 3.6V

VIN = 2.7V

VIN = 5.5V

LM3674

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SNVS405F –DECEMBER 2005–REVISED MAY 2013

Typical Performance Characteristics

(unless otherwise stated: VIN= 3.6V, V

Quiescent Current vs. Supply Voltage

(FB = 0V, No Switching) IQShutdown vs. Temp

Figure 5. Figure 6.

Feedback Bias Current vs. Temp Output Voltage vs. Supply Voltage

= 1.5V, TA= 25°C)

OUT

Figure 7. Figure 8.

Output Voltage vs. Temperature Output Voltage vs. Output Current

Copyright © 2005–2013, Texas Instruments Incorporated Submit Documentation Feedback 7

Figure 9. Figure 10.

Product Folder Links: LM3674

-30

-

10

_

10

_

30

50_70_90

_

TEMPERATURE (°C)

1.88

_

1.90

_

1.92

_

1.94

_

1.96

_

1.98

_

2.00

FREQUENCY (MHz)

VIN = 2.7V

VIN = 4.5V

VIN = 3.6V

I

OUT

= 300 mA

-10 10 30 50 70 90 110
TEMPERATURE (°C)

100

150

200

250

300

350

400

450

500

550

600

R

DS(ON)

(

m:)

-30

NFET

VIN = 4.5V

PFET

VIN = 2.7V

VIN = 4.5V

VIN = 3.6V

VIN = 3.6V

VIN = 2.7V

LM3674

SNVS405F –DECEMBER 2005–REVISED MAY 2013

Typical Performance Characteristics (continued)

(unless otherwise stated: VIN= 3.6V, V

R

vs. Temperature (V

DSON

Figure 11. Figure 12.

Efficiency vs. Output Current Efficiency vs. Output Current

(V

= 1.5V, L = 2.2uH, DCR = 200mΩ) (V

OUT

OUT

= 1.5V, TA= 25°C)

Efficiency vs. Output Current

= 1.2V, L = 2.2uH, DCR = 200mΩ)

OUT

= 1.8V, L = 2.2uH, DCR = 200mΩ)

OUT

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Figure 13. Figure 14.

Efficiency vs. Output Current

(V

= 3.3V, L = 2.2uH, DCR = 200mΩ) Switching Frequency vs. Temperature

OUT

8 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated

Figure 15. Figure 16.

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