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LM2734

www.ti.com

SNVS288I –SEPTEMBER 2004–REVISED APRIIL 2013

LM2734 Thin SOT 1A Load Step-Down DC-DC Regulator

Check for Samples: LM2734

FEATURES

DESCRIPTION

The LM2734 regulator is a monolithic, high frequency,

234

• Thin SOT-6 Package

PWM step-down DC/DC converter in a 6-pin Thin

• 3.0V to 20V Input Voltage Range

SOT package. It provides all the active functions to

• 0.8V to 18V Output Voltage Range

provide local DC/DC conversion with fast transient

response and accurate regulation in the smallest

• 1A Output Current

possible PCB area.

• 550kHz (LM2734Y) and 1.6MHz (LM2734X)

With a minimum of external components and online

Switching Frequencies

design support through WEBENCH

, the LM2734 is

• 300mΩ NMOS Switch

easy to use. The ability to drive 1A loads with an

• 30nA Shutdown Current

internal 300mΩ NMOS switch using state-of-the-art

• 0.8V, 2% Internal Voltage Reference

0.5µm BiCMOS technology results in the best power

density available. The world class control circuitry

• Internal Soft-Start

allows for on-times as low as 13ns, thus supporting

• Current-Mode, PWM Operation

exceptionally high frequency conversion over the

• WEBENCH

Online Design Tool

entire 3V to 20V input operating range down to the

minimum output voltage of 0.8V. Switching frequency

• Thermal Shutdown

is internally set to 550kHz (LM2734Y) or 1.6MHz

• LM2734XQ/LM2734YQ are AEC-Q100 Grade 1

(LM2734X), allowing the use of extremely small

Qualified and are Manufactured on an

surface mount inductors and chip capacitors. Even

Automotive Grade Flow

though the operating frequencies are very high,

efficiencies up to 90% are easy to achieve. External

APPLICATIONS

shutdown is included, featuring an ultra-low stand-by

current of 30nA. The LM2734 utilizes current-mode

• Local Point of Load Regulation

control and internal compensation to provide high-

• Core Power in HDDs

performance regulation over a wide range of

• Set-Top Boxes

operating conditions. Additional features include

internal soft-start circuitry to reduce inrush current,

• Battery Powered Devices

pulse-by-pulse current limit, thermal shutdown, and

• USB Powered Devices

output over-voltage protection.

• DSL Modems

• Notebook Computers

• Automotive

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.

2WEBENCH is a registered trademark of Texas Instruments, Inc..

3WEBENCH is a registered trademark of Texas Instruments.

4All other 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.

Summary of content (32 pages)

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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 LM2734 Thin SOT 1A Load Step-Down DC-DC Regulator Check for Samples: LM2734 FEATURES DESCRIPTION • • • • • The LM2734 regulator is a monolithic, high frequency, PWM step-down DC/DC converter in a 6-pin Thin SOT package. It provides all the active functions to provide local DC/DC conversion with fast transient response and accurate regulation in the smallest possible PCB area. 1 234 • • • • • • • • Thin SOT-6 Package 3.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com Typical Application Circuit D2 VIN BOOST VIN C3 C1 L1 SW VOUT LM2734 ON D1 C2 EN R1 OFF FB GND R2 Figure 1. Figure 2. Efficiency vs Load Current VIN = 5V, VOUT = 3.3V Connection Diagram BOOST 1 6 SW 1 6 GND 2 5 VIN 2 5 FB 3 4 EN 3 4 Figure 3. 6-Lead SOT See Package Number DDC (R-PDSO-G6) Figure 4.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 Absolute Maximum Ratings (1) (2) VIN -0.5V to 24V SW Voltage -0.5V to 24V Boost Voltage -0.5V to 30V Boost to SW Voltage -0.5V to 6.0V FB Voltage -0.5V to 3.0V EN Voltage -0.5V to (VIN + 0.3V) Junction Temperature ESD Susceptibility 150°C (3) 2kV Storage Temp. Range -65°C to 150°C Soldering Information Reflow Peak Pkg. Temp.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com Electrical Characteristics Specifications with standard typeface are for TJ = 25°C, and those in boldface type apply over the full Operating Temperature Range (TJ = -40°C to 125°C). VIN = 5V, VBOOST - VSW = 5V unless otherwise specified. Datasheet min/max specification limits are ensured by design, test, or statistical analysis.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 Typical Performance Characteristics All curves taken at VIN = 5V, VBOOST - VSW = 5V, L1 = 4.7 µH ("X"), L1 = 10 µH ("Y"), and TA = 25°C, unless specified otherwise. Efficiency vs Load Current - "X" VOUT = 5V Efficiency vs Load Current - "Y" VOUT = 5V Figure 5. Figure 6. Efficiency vs Load Current - "X" VOUT = 3.3V Efficiency vs Load Current - "Y" VOUT = 3.3V Figure 7. Figure 8. Efficiency vs Load Current - "X" VOUT = 1.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com Typical Performance Characteristics (continued) All curves taken at VIN = 5V, VBOOST - VSW = 5V, L1 = 4.7 µH ("X"), L1 = 10 µH ("Y"), and TA = 25°C, unless specified otherwise. 6 Oscillator Frequency vs Temperature - "X" Oscillator Frequency vs Temperature - "Y" Figure 11. Figure 12. Current Limit vs Temperature VIN = 5V Current Limit vs Temperature VIN = 20V Figure 13. Figure 14.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 Typical Performance Characteristics (continued) All curves taken at VIN = 5V, VBOOST - VSW = 5V, L1 = 4.7 µH ("X"), L1 = 10 µH ("Y"), and TA = 25°C, unless specified otherwise. IQ Switching vs Temperature Line Regulation - "X" VOUT = 1.5V, IOUT = 500mA Figure 17. Figure 18. Line Regulation - "Y" VOUT = 1.5V, IOUT = 500mA Line Regulation - "X" VOUT = 3.3V, IOUT = 500mA Figure 19. Figure 20. Line Regulation - "Y" VOUT = 3.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com Block Diagram VIN VIN Current-Sense Amplifier OFF EN Internal Regulator and Enable Circuit CIN D2 Thermal Shutdown BOOST VBOOST Under Voltage Lockout Oscillator RSENSE + - Current Limit Output Control Logic Reset Pulse + ISENSE + + Corrective Ramp 0.3: Switch Driver SW OVP Comparator - ON Error Signal D 1 + PWM Comparator CBOOST VSW L IL VOUT COUT 0.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 APPLICATION INFORMATION THEORY OF OPERATION The LM2734 is a constant frequency PWM buck regulator IC that delivers a 1A load current. The regulator has a preset switching frequency of either 550kHz (LM2734Y) or 1.6MHz (LM2734X). These high frequencies allow the LM2734 to operate with small surface mount capacitors and inductors, resulting in DC/DC converters that require a minimum amount of board space.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com VBOOST D2 BOOST VIN VIN LM2734 CIN CBOOST L SW VOUT GND COUT D1 Figure 24. VOUT Charges CBOOST When the LM2734 starts up, internal circuitry from the BOOST pin supplies a maximum of 20mA to CBOOST. This current charges CBOOST to a voltage sufficient to turn the switch on. The BOOST pin will continue to source current to CBOOST until the voltage at the feedback pin is greater than 0.76V.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 D2 D3 VIN BOOST VIN CIN VBOOST CBOOST LM2734 L VOUT SW GND C OUT D1 Figure 25. Zener Reduces Boost Voltage from VIN An alternative method is to place the zener diode D3 in a shunt configuration as shown in Figure 26. A small 350mW to 500mW 5.1V zener in a SOT or SOD package can be used for this purpose. A small ceramic capacitor such as a 6.3V, 0.1µF capacitor (C4) should be placed in parallel with the zener diode.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com ENABLE PIN / SHUTDOWN MODE The LM2734 has a shutdown mode that is controlled by the enable pin (EN). When a logic low voltage is applied to EN, the part is in shutdown mode and its quiescent current drops to typically 30nA. Switch leakage adds another 40nA from the input supply. The voltage at this pin should never exceed VIN + 0.3V. SOFT-START This function forces VOUT to increase at a controlled rate during start up.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 The inductor value determines the output ripple current. Lower inductor values decrease the size of the inductor, but increase the output ripple current. An increase in the inductor value will decrease the output ripple current. The ratio of ripple current (ΔiL) to output current (IO) is optimized when it is set between 0.3 and 0.4 at 1A. The ratio r is defined as: r= 'iL lO (15) One must also ensure that the minimum current limit (1.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com provide stable operation. As a result, surface mount capacitors are strongly recommended. Sanyo POSCAP, Tantalum or Niobium, Panasonic SP or Cornell Dubilier ESR, and multilayer ceramic capacitors (MLCC) are all good choices for both input and output capacitors and have very low ESL. For MLCCs it is recommended to use X7R or X5R dielectrics.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 PCB Layout Considerations When planning layout there are a few things to consider when trying to achieve a clean, regulated output. The most important consideration when completing the layout is the close coupling of the GND connections of the CIN capacitor and the catch diode D1. These ground ends should be close to one another and be connected to the GND plane with at least two through-holes.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com D2 VIN 12V BOOST VIN C3 C1 R3 L1 VOUT 3.3V SW LM2734 D1 C2 ON EN R1 CFF OFF FB GND R2 Figure 28. LM2734X (1.6MHz) VBOOST Derived from VOUT 12V to 3.3V/1A Table 2. Bill of Materials for Figure 28 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator NSC LM2734X C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK C3, Boost Cap 0.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 C4 D3 R4 D2 BOOST VIN VIN C3 C1 R3 L1 VOUT SW LM2734 ON D1 C2 EN OFF R1 FB GND R2 Figure 29. LM2734X (1.6MHz) VBOOST Derived from VSHUNT 18V to 1.5V/1A Table 3. Bill of Materials for Figure 29 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734X Texas Instruments C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK C3, Boost Cap 0.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com D3 D2 BOOST VIN VIN C1 C3 R3 L1 VOUT SW LM2734 ON D1 EN C2 R1 OFF FB GND R2 Figure 30. LM2734X (1.6MHz) VBOOST Derived from Series Zener Diode (VIN) 15V to 1.5V/1A Table 4. Bill of Materials for Figure 30 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734X Texas Instruments C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK C3, Boost Cap 0.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 D3 D2 VIN BOOST VIN C3 C1 R3 L1 VOUT SW LM2734 ON D1 EN C2 R1 OFF FB GND R2 Figure 31. LM2734X (1.6MHz) VBOOST Derived from Series Zener Diode (VOUT) 15V to 9V/1A Table 5. Bill of Materials for Figure 31 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734X Texas Instruments C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 16V, X5R C3216X5R1C226M TDK C3, Boost Cap 0.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com LM2734Y Circuit Examples D2 VIN BOOST VIN C3 C1 L1 R3 VOUT SW LM2734 ON D1 EN C2 R1 OFF FB GND R2 Figure 32. LM2734Y (550kHz) VBOOST Derived from VIN 5V to 1.5V/1A Table 6. Bill of Materials for Figure 32 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734Y Texas Instruments C1, Input Cap 10µF, 6.3V, X5R C3216X5ROJ106M TDK C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK C3, Boost Cap 0.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 D2 VIN 12V BOOST VIN C3 C1 R3 L1 VOUT 3.3V SW LM2734 D1 C2 ON EN R1 CFF OFF FB GND R2 Figure 33. LM2734Y (550kHz) VBOOST Derived from VOUT 12V to 3.3V/1A Table 7. Bill of Materials for Figure 33 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734Y Texas Instruments C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK C3, Boost Cap 0.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com C4 D3 R4 D2 BOOST VIN VIN C3 C1 R3 L1 VOUT SW LM2734 ON D1 C2 EN OFF R1 FB GND R2 Figure 34. LM2734Y (550kHz) VBOOST Derived from VSHUNT 18V to 1.5V/1A Table 8. Bill of Materials for Figure 34 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734Y Texas Instruments C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK C3, Boost Cap 0.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 D3 D2 BOOST VIN VIN C1 C3 R3 L1 VOUT SW LM2734 ON D1 EN C2 R1 OFF FB GND R2 Figure 35. LM2734Y (550kHz) VBOOST Derived from Series Zener Diode (VIN) 15V to 1.5V/1A Table 9. Bill of Materials for Figure 35 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734Y Texas Instruments C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 6.3V, X5R C3216X5ROJ226M TDK C3, Boost Cap 0.
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LM2734 SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 www.ti.com D3 D2 VIN BOOST VIN C3 C1 R3 L1 VOUT SW LM2734 ON D1 EN C2 R1 OFF FB GND R2 Figure 36. LM2734Y (550kHz) VBOOST Derived from Series Zener Diode (VOUT) 15V to 9V/1A Table 10. Bill of Materials for Figure 36 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734Y Texas Instruments C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 16V, X5R C3216X5R1C226M TDK C3, Boost Cap 0.
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LM2734 www.ti.com SNVS288I – SEPTEMBER 2004 – REVISED APRIIL 2013 REVISION HISTORY Changes from Revision H (April 2013) to Revision I • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM2734XMK/NOPB SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2734XMKX/NOPB SOT DDC 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2734XQMK/NOPB SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2734XMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM2734XMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0 LM2734XQMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM2734XQMKE/NOPB SOT DDC 6 250 210.0 185.0 35.0 LM2734XQMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0 LM2734YMK SOT DDC 6 1000 210.0 185.0 35.
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