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LM2734Z

www.ti.com

SNVS334E –JANUARY 2005–REVISED APRIL 2013

LM2734Z/LM2734ZQ Thin SOT 1A Load Step-Down DC-DC Regulator

Check for Samples: LM2734Z

FEATURES

DESCRIPTION

The LM2734Z regulator is a monolithic, high

• Thin SOT-6 Package, or 6 Lead WSON

frequency, PWM step-down DC/DC converter

Package

assembled in a 6-pin Thin SOT and WSON non pull

• 3.0V to 20V Input Voltage Range

back 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.

• 3MHz Switching Frequency

With a minimum of external components and online

• 300mΩ NMOS Switch

design support through WEBENCH™, the LM2734Z

• 30nA Shutdown Current

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

• 0.8V, 2% Internal Voltage Reference

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

0.5µm BiCMOS technology results in the best power

• Internal Soft-Start

density available. The world class control circuitry

• Current-Mode, PWM Operation

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

• Thermal Shutdown

exceptionally high frequency conversion over the

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

• LM2734ZQ is AEC-Q100 Grade 1 Qualified and

minimum output voltage of 0.8V. Switching frequency

is Manufactured on an Automotive Grade Flow

is internally set to 3MHz, allowing the use of

extremely small surface mount inductors and chip

APPLICATIONS

capacitors. Even though the operating frequency is

• DSL Modems

very high, efficiencies up to 85% are easy to achieve.

External shutdown is included, featuring an ultra-low

• Local Point of Load Regulation

stand-by current of 30nA. The LM2734Z utilizes

• Battery Powered Devices

current-mode control and internal compensation to

• USB Powered Devices

provide high-performance regulation over a wide

range of operating conditions. Additional features

• Automotive

include internal soft-start circuitry to reduce inrush

current, pulse-by-pulse current limit, thermal

shutdown, and output over-voltage protection.

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 trademark of Texas Instruments, Inc..

3All 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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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 LM2734Z/LM2734ZQ Thin SOT 1A Load Step-Down DC-DC Regulator Check for Samples: LM2734Z FEATURES DESCRIPTION • The LM2734Z regulator is a monolithic, high frequency, PWM step-down DC/DC converter assembled in a 6-pin Thin SOT and WSON non pull back 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.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com Typical Application Circuit Efficiency vs Load Current VIN = 5V, VOUT = 3.3V D2 VIN BOOST VIN C3 C1 L1 SW VOUT LM2734 ON D1 EN C2 R1 OFF FB GND R2 Connection Diagrams BOOST 1 6 SW FB 1 GND 2 5 VIN GND 2 FB 3 4 EN BOOST 3 Figure 1. 6-Lead SOT See Package Number DDC (R-PDSO-G6) DAP 6 EN 5 VIN 4 SW Figure 2.
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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 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 Soldering Information (1) (2) (3) -65°C to 150°C Infrared/Convection Reflow (15sec) 220°C Wave Soldering Lead Temp.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 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 specified by design, test, or statistical analysis.
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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 Typical Performance Characteristics All curves taken at VIN = 5V, VBOOST - VSW = 5V, L1 = 2.2 µH and TA = 25°C, unless specified otherwise. Efficiency vs Load Current VOUT = 5V Efficiency vs Load Current VOUT = 3.3V Figure 3. Figure 4. Efficiency vs Load Current VOUT = 1.5V Oscillator Frequency vs Temperature Figure 5. Figure 6. Line Regulation VOUT = 1.5V, IOUT = 500mA Line Regulation VOUT = 3.3V, IOUT = 500mA Figure 7. Figure 8.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com Block Diagram VIN VIN Current-Sense Amplifier OFF EN Internal Regulator and Enable Circuit RSENSE + - CIN D2 Thermal Shutdown BOOST VBOOST Under Voltage Lockout Current Limit Oscillator 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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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 VSW D = TON/TSW VIN SW Voltage TOFF TON 0 VD t TSW IL IPK Inductor Current t 0 Figure 9. LM2734Z Waveforms of SW Pin Voltage and Inductor Current BOOST FUNCTION Capacitor CBOOST and diode D2 in Figure 10 are used to generate a voltage VBOOST. VBOOST - VSW is the gate drive voltage to the internal NMOS control switch. To properly drive the internal NMOS switch during its on-time, VBOOST needs to be at least 1.6V greater than VSW.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com In the Simplifed Block Diagram of Block Diagram, capacitor CBOOST and diode D2 supply the gate-drive current for the NMOS switch. Capacitor CBOOST is charged via diode D2 by VIN. During a normal switching cycle, when the internal NMOS control switch is off (TOFF) (refer to Figure 9), VBOOST equals VIN minus the forward voltage of D2 (VFD2), during which the current in the inductor (L) forward biases the Schottky diode D1 (VFD1).
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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 R3 will then be given by R3 = (VIN - VZENER) / (1.25 x IBOOST + IZENER) (10) For example, let VIN = 10V, VZENER = 5V, VD2 = 0.7V, IZENER = 1mA, and duty cycle D = 50%. Then IBOOST = (0.5 + 0.5) x (5 - 0.7) mA = 4.3mA R3 = (10V - 5V) / (1.25 x 4.3mA + 1mA) = 787Ω (11) (12) VZ C4 D2 D3 R3 BOOST VIN VIN C IN VBOOST CBOOST LM2734 L SW VOUT GND D1 COUT Figure 12.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com THERMAL SHUTDOWN Thermal shutdown limits total power dissipation by turning off the output switch when the IC junction temperature exceeds 165°C. After thermal shutdown occurs, the output switch doesn’t turn on until the junction temperature drops to approximately 150°C.
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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 where fs is the switching frequency and IO is the output current. When selecting an inductor, make sure that it is capable of supporting the peak output current without saturating. Inductor saturation will result in a sudden reduction in inductance and prevent the regulator from operating correctly.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com CATCH DIODE The catch diode (D1) conducts during the switch off-time. A Schottky diode is recommended for its fast switching times and low forward voltage drop. The catch diode should be chosen so that its current rating is greater than: ID1 = IO x (1-D) (23) The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin.
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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 Calculations for determining the most significant power losses are shown below. Other losses totaling less than 2% are not discussed. Power loss (PLOSS) is the sum of two basic types of losses in the converter, switching and conduction. Conduction losses usually dominate at higher output loads, where as switching losses remain relatively fixed and dominate at lower output loads.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com Design Example 1: Operating Conditions VIN 5.0V POUT 2.5W VOUT 2.5V PDIODE 151mW IOUT 1.0A PIND 75mW VD 0.35V PSWF 53mW Freq 3MHz PSWR 53mW IQ 1.5mA PCOND 187mW TRISE 8ns PQ 7.5mW TFALL 8ns PBOOST 21mW RDSON 330mΩ PLOSS 548mW INDDCR 75mΩ D 0.
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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 Thermal impedance from the silicon junction to the ambient air is defined as: TJ - TA RTJA = Power (40) This impedance can vary depending on the thermal properties of the PCB. This includes PCB size, weight of copper used to route traces and ground plane, and number of layers within the PCB. The type and number of thermal vias can also make a large difference in the thermal impedance. Thermal vias are necessary in most applications.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com 165oC - TA RTJA = PINTERNAL (44) Once this is determined, the maximum ambient temperature allowed for a desired junction temperature can be found. Design Example 3: Operating Conditions Package SOT-6 VIN 12.0V POUT 2.475W VOUT 3.30V PDIODE 523mW IOUT 750mA PIND 56.25mW VD 0.35V PSWF 108mW Freq 3MHz PSWR 108mW IQ 1.5mA PCOND 68.
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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 WSON PACKAGE The LM2734Z is packaged in a Thin SOT-6 package and the 6–pin WSON. The WSON package has the same footprint as the Thin SOT-6, but is thermally superior due to the exposed ground paddle on the bottom of the package. Figure 14. No Pullback WSON Configuration RθJA of the WSON package is normally two to three times better than that of the Thin SOT-6 package for a similar PCB configuration (area, copper weight, thermal vias).
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com 6PCOND + PSWF + PSWR + PQ + PBOOST = PINTERNAL PINTERNAL = 322 mW (48) This example follows example 2, but uses the WSON package. Using a standard Texas Instruments WSON-6 demonstration board, use Method 2 to determine RθJA of the board. The four layer PCB is constructed using FR4 with 1/2oz copper traces. The copper ground plane is on the bottom layer. The ground plane is accessed by four vias. The board measures 2.5cm x 3cm.
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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 LM2734Z Design Examples D2 VIN BOOST VIN C3 C1 L1 R3 VOUT SW LM2734 ON D1 EN C2 R1 OFF FB GND R2 Figure 16. VBOOST Derived from VIN Operating Conditions: 5V to 1.5V/1A Table 2. Bill of Materials for Figure 16 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734ZX Texas Instruments C1, Input Cap 10µF, 6.3V, X5R C3216X5ROJ106M TDK C2, Output Cap 10µF, 6.3V, X5R C3216X5ROJ106M TDK C3, Boost Cap 0.
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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com D2 VIN BOOST VIN C3 C1 L1 R3 VOUT SW LM2734 ON D1 C2 EN OFF R1 FB GND R2 Figure 17. VBOOST Derived from VOUT 12V to 3.3V/1A Table 3. Bill of Materials for Figure 17 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734ZX 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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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 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 18. VBOOST Derived from VSHUNT 18V to 1.5V/1A Table 4. Bill of Materials for Figure 18 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734ZX 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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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com D2 D3 BOOST VIN VIN C1 C3 R3 L1 VOUT SW LM2734 ON D1 EN C2 R1 OFF FB GND R2 Figure 19. VBOOST Derived from Series Zener Diode (VIN) 15V to 1.5V/1A Table 5. Bill of Materials for Figure 19 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734ZX 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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LM2734Z www.ti.com SNVS334E – JANUARY 2005 – REVISED APRIL 2013 D3 D2 VIN BOOST VIN C3 C1 R3 L1 VOUT SW LM2734 ON D1 EN C2 R1 OFF FB GND R2 Figure 20. VBOOST Derived from Series Zener Diode (VOUT) 15V to 9V/1A Table 6. Bill of Materials for Figure 20 Part ID Part Value Part Number Manufacturer U1 1A Buck Regulator LM2734ZX 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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LM2734Z SNVS334E – JANUARY 2005 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision D (April 2013) to Revision E • 24 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 7-Oct-2013 (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Oct-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 LM2734ZMK/NOPB SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2734ZMKX/NOPB SOT DDC 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2734ZQMK/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 23-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2734ZMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM2734ZMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0 LM2734ZQMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM2734ZQMKE/NOPB SOT DDC 6 250 210.0 185.0 35.0 LM2734ZQMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0 LM2734ZQSD/NOPB WSON NGG 6 1000 213.0 191.0 55.
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MECHANICAL DATA NGG0006A SDE06A (Rev A) www.ti.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.