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BOOST

GND

OUT

OFF

LM2736

www.ti.com

SNVS316F –SEPTEMBER 2004–REVISED APRIL 2013

LM2736 Thin SOT 750mA Load Step-Down DC-DC Regulator

Check for Samples: LM2736

FEATURES

DESCRIPTION

The LM2736 regulator is a monolithic, high frequency,

• Thin SOT-6 Package

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

• 3.0V to 18V Input Voltage Range

SOT package. It provides all the active functions to

• 1.25V to 16V Output Voltage Range

provide local DC/DC conversion with fast transient

response and accurate regulation in the smallest

• 750mA Output Current

possible PCB area.

• 550kHz (LM2736Y) and 1.6MHz (LM2736X)

With a minimum of external components and online

Switching Frequencies

design support through WEBENCH

, the LM2736 is

• 350mΩ NMOS Switch

easy to use. The ability to drive 750mA loads with an

• 30nA Shutdown Current

internal 350mΩ NMOS switch using state-of-the-art

• 1.25V, 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 18V input operating range down to the

minimum output voltage of 1.25V. Switching

• Thermal Shutdown

frequency is internally set to 550kHz (LM2736Y) or

1.6MHz (LM2736X), allowing the use of extremely

APPLICATIONS

small surface mount inductors and chip capacitors.

• Local Point of Load Regulation

Even though the operating frequencies are very high,

efficiencies up to 90% are easy to achieve. External

• Core Power in HDDs

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

• Set-Top Boxes

current of 30nA. The LM2736 utilizes current-mode

• Battery Powered Devices

control and internal compensation to provide high-

performance regulation over a wide range of

• USB Powered Devices

operating conditions. Additional features include

• DSL Modems

internal soft-start circuitry to reduce inrush current,

• Notebook Computers

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

output over-voltage protection.

Typical Application Circuit

Efficiency vs Load Current "X"

= 5V, V

OUT

= 3.3V

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.

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 (31 pages)

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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 LM2736 Thin SOT 750mA Load Step-Down DC-DC Regulator Check for Samples: LM2736 FEATURES DESCRIPTION • • • • • The LM2736 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 23 • • • • • • • Thin SOT-6 Package 3.
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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com Connection Diagram BOOST 1 6 SW 1 6 GND 2 5 VIN 2 5 FB 3 4 EN 3 4 Figure 1. 6-Lead SOT See Package Number DDC (R-PDSO-G6) Figure 2. Pin 1 Indentification PIN DESCRIPTIONS Pin Name 1 BOOST Function 2 GND 3 FB Feedback pin. Connect FB to the external resistor divider to set output voltage. 4 EN Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than VIN + 0.3V.
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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 Operating Ratings (1) VIN 3V to 18V SW Voltage -0.5V to 18V Boost Voltage -0.5V to 23V Boost to SW Voltage 1.6V to 5.5V −40°C to +125°C Junction Temperature Range Thermal Resistance θJA (2) (1) (2) 118°C/W Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not ensured.
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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com 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. 4 Efficiency vs Load Current - "X" VOUT = 5V Efficiency vs Load Current - "Y" VOUT = 5V Figure 3. Figure 4. Efficiency vs Load Current - "X" VOUT = 3.3V Efficiency vs Load Current - "Y" VOUT = 3.3V Figure 5. Figure 6. Efficiency vs Load Current - "X" VOUT = 1.
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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 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. Oscillator Frequency vs Temperature - "X" Oscillator Frequency vs Temperature - "Y" Figure 9. Figure 10. Current Limit vs Temperature VIN = 18V, VIN = 5V VFB vs Temperature Figure 11. Figure 12. RDSON vs Temperature IQ Switching vs Temperature Figure 13.
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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 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 Line Regulation - "X" VOUT = 1.5V, IOUT = 500mA Line Regulation - "Y" VOUT = 1.5V, IOUT = 500mA Figure 15. Figure 16. Line Regulation - "X" VOUT = 3.3V, IOUT = 500mA Line Regulation - "Y" VOUT = 3.3V, IOUT = 500mA Figure 17. Figure 18.
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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 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 1.
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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com VSW D = TON/TSW VIN SW Voltage TOFF TON 0 VD t TSW IL IPK Inductor Current t 0 Figure 20. LM2736 Waveforms of SW Pin Voltage and Inductor Current BOOST FUNCTION Capacitor CBOOST and diode D2 in Figure 21 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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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 When the NMOS switch turns on (TON), the switch pin rises to VSW = VIN – (RDSON x IL), (2) forcing VBOOST to rise thus reverse biasing D2. The voltage at VBOOST is then VBOOST = 2VIN – (RDSON x IL) – VFD2 + VFD1 (3) which is approximately 2VIN - 0.4V (4) for many applications. Thus the gate-drive voltage of the NMOS switch is approximately VIN - 0.
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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com IBOOST = 0.49 x (0.5 + 0.54) x (5 - 0.7) mA = 2.19mA R3 = (10V - 5V) / (1.4 x 2.19mA + 1mA) = 1.23kΩ (10) (11) VZ C4 D2 D3 R3 VIN BOOST VIN VBOOST CBOOST CIN L VOUT SW GND D1 COUT Figure 23. Boost Voltage Supplied from the Shunt Zener on VIN ENABLE PIN / SHUTDOWN MODE The LM2736 has a shutdown mode that is controlled by the enable pin (EN).
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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 Design Guide INDUCTOR SELECTION The Duty Cycle (D) can be approximated quickly using the ratio of output voltage (VO) to input voltage (VIN): VO D= VIN (12) The catch diode (D1) forward voltage drop and the voltage drop across the internal NMOS must be included to calculate a more accurate duty cycle.
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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com be specified with a saturation current limit of >0.7A. There is no need to specify the saturation or peak current of the inductor at the 1.5A typical switch current limit. The difference in inductor size is a factor of 5. Because of the operating frequency of the LM2736, ferrite based inductors are preferred to minimize core losses. This presents little restriction since the variety of ferrite based inductors is huge.
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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 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) (22) The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin.
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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com LM2736X Circuit Examples D2 VIN BOOST VIN C3 C1 L1 R3 VOUT SW ON D1 EN C2 R1 OFF FB GND R2 Figure 24. LM2736X (1.6MHz) VBOOST Derived from VIN 5V to 1.5V/750mA Table 1. Bill of Materials for Figure 24 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736X TI 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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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 D2 VIN BOOST VIN C3 C1 R3 L1 SW ON VOUT D1 C2 EN OFF R1 FB GND R2 Figure 25. LM2736X (1.6MHz) VBOOST Derived from VOUT 12V to 3.3V/750mA Table 2. Bill of Materials for Figure 25 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736X TI 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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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com C4 D3 R4 D2 BOOST VIN VIN C3 C1 R3 L1 VOUT SW ON D1 C2 EN OFF R1 FB GND R2 Figure 26. LM2736X (1.6MHz) VBOOST Derived from VSHUNT 18V to 1.5V/750mA Table 3. Bill of Materials for Figure 26 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736X TI 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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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 D3 D2 BOOST VIN VIN C1 C3 L1 R3 VOUT SW ON D1 EN C2 R1 OFF FB GND R2 Figure 27. LM2736X (1.6MHz) VBOOST Derived from Series Zener Diode (VIN) 15V to 1.5V/750mA Table 4. Bill of Materials for Figure 27 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736X TI 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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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com D3 D2 VIN BOOST VIN C3 R3 C1 L1 VOUT SW ON D1 EN C2 R1 OFF FB GND R2 Figure 28. LM2736X (1.6MHz) VBOOST Derived from Series Zener Diode (VOUT) 15V to 9V/750mA Table 5. Bill of Materials for Figure 28 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736X TI C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 16V, X5R C3216X5R1C226M TDK C3, Boost Cap 0.
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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 LM2736Y Circuit Examples D2 VIN BOOST VIN C3 C1 L1 R3 VOUT SW ON D1 EN C2 R1 OFF FB GND R2 Figure 29. LM2736Y (550kHz) VBOOST Derived from VIN 5V to 1.5V/750mA Table 6. Bill of Materials for Figure 29 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736Y TI 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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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com D2 VIN BOOST VIN C3 C1 R3 L1 SW ON VOUT D1 C2 EN OFF R1 FB GND R2 Figure 30. LM2736Y (550kHz) VBOOST Derived from VOUT 12V to 3.3V/750mA Table 7. Bill of Materials for Figure 30 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736Y TI 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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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 C4 D3 R4 D2 BOOST VIN VIN C3 C1 R3 L1 VOUT SW ON D1 C2 EN OFF R1 FB GND R2 Figure 31. LM2736Y (550kHz) VBOOST Derived from VSHUNT 18V to 1.5V/750mA Table 8. Bill of Materials for Figure 31 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736Y TI 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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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com D3 D2 BOOST VIN VIN C3 C1 L1 R3 VOUT SW ON D1 EN C2 R1 OFF FB GND R2 Figure 32. LM2736Y (550kHz) VBOOST Derived from Series Zener Diode (VIN) 15V to 1.5V/750mA Table 9. Bill of Materials for Figure 32 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736Y TI 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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LM2736 www.ti.com SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 D3 D2 VIN BOOST VIN C3 C1 R3 L1 VOUT SW ON D1 EN C2 R1 OFF FB GND R2 Figure 33. LM2736Y (550kHz) VBOOST Derived from Series Zener Diode (VOUT) 15V to 9V/750mA Table 10. Bill of Materials for Figure 33 Part ID Part Value Part Number Manufacturer U1 750mA Buck Regulator LM2736Y TI C1, Input Cap 10µF, 25V, X7R C3225X7R1E106M TDK C2, Output Cap 22µF, 16V, X5R C3216X5R1C226M TDK C3, Boost Cap 0.
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LM2736 SNVS316F – SEPTEMBER 2004 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision E (April 2013) to Revision F • 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 1-Nov-2013 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-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 LM2736XMK SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2736XMK/NOPB SOT DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2736XMKX/NOPB SOT DDC 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2736XMK SOT DDC 6 1000 210.0 185.0 35.0 LM2736XMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM2736XMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0 LM2736YMK SOT DDC 6 1000 210.0 185.0 35.0 LM2736YMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM2736YMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.
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