lm2736xmkx National Semiconductor Corporation, lm2736xmkx Datasheet

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lm2736xmkx

Manufacturer Part Number
lm2736xmkx
Description
Thin Sot23 750ma Load Step-down Dc-dc Regulator
Manufacturer
National Semiconductor Corporation
Datasheet

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LM2736XMKX
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© 2005 National Semiconductor Corporation
LM2736
Thin SOT23 750mA Load Step-Down DC-DC Regulator
General Description
The LM2736 regulator is a monolithic, high frequency, PWM
step-down DC/DC converter in a 6-pin Thin SOT23 package.
It provides all the active functions to provide local DC/DC
conversion with fast transient response and accurate regu-
lation in the smallest possible PCB area.
With a minimum of external components and online design
support through WEBENCH
The ability to drive 750mA loads with an internal 350mΩ
NMOS switch using state-of-the-art 0.5µm BiCMOS technol-
ogy results in the best power density available. The world
class control circuitry allows for on-times as low as 13ns,
thus supporting exceptionally high frequency conversion
over the entire 3V to 18V input operating range down to the
minimum output voltage of 1.25V. Switching frequency is
internally set to 550kHz (LM2736Y) or 1.6MHz (LM2736X),
allowing the use of extremely small surface mount inductors
and chip capacitors. Even though the operating frequencies
are very high, efficiencies up to 90% are easy to achieve.
External shutdown is included, featuring an ultra-low
stand-by current of 30nA. The LM2736 utilizes current-mode
control and internal compensation to provide high-
performance regulation over a wide range of operating con-
ditions. Additional features include internal soft-start circuitry
to reduce inrush current, pulse-by-pulse current limit, ther-
mal shutdown, and output over-voltage protection.
Typical Application Circuit
WEBENCH
is a trademark of Transim.
®
, the LM2736 is easy to use.
DS201242
20124201
Features
n Thin SOT23-6 package
n 3.0V to 18V input voltage range
n 1.25V to 16V output voltage range
n 750mA output current
n 550kHz (LM2736Y) and 1.6MHz (LM2736X)
n 350mΩ NMOS switch
n 30nA shutdown current
n 1.25V, 2% internal voltage reference
n Internal soft-start
n Current-Mode, PWM operation
n WEBENCH
n Thermal shutdown
Applications
n Local Point of Load Regulation
n Core Power in HDDs
n Set-Top Boxes
n Battery Powered Devices
n USB Powered Devices
n DSL Modems
n Notebook Computers
switching frequencies
Efficiency vs Load Current "X"
®
online design tool
V
IN
= 5V, V
OUT
= 3.3V
20124251
January 2005
www.national.com

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lm2736xmkx Summary of contents

Page 1

... Typical Application Circuit WEBENCH ™ trademark of Transim. © 2005 National Semiconductor Corporation Features n Thin SOT23-6 package n 3.0V to 18V input voltage range n 1.25V to 16V output voltage range n 750mA output current n 550kHz (LM2736Y) and 1 ...

Page 2

... Connection Diagrams 6-Lead TSOT NS Package Number MK06A Ordering Information Order Number Package Type LM2736XMK LM2736YMK TSOT-6 LM2736XMKX LM2736YMKX * Contact the local sales office for the lead-free package. Pin Description Pin 1 BOOST www.national.com 20124205 NSC Package Drawing Package Marking SHAB ...

Page 3

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications Voltage Boost Voltage Boost to SW Voltage FB Voltage EN Voltage Junction Temperature ESD Susceptibility (Note ...

Page 4

Typical Performance Characteristics ("X"), µH ("Y"), and T = 25˚C, unless specified otherwise. A Efficiency vs Load Current - "X" V Efficiency vs Load Current - "X" V Efficiency vs Load Current - "X" V www.national.com All ...

Page 5

Typical Performance Characteristics ("X"), µH ("Y"), and T = 25˚C, unless specified otherwise. (Continued) A Oscillator Frequency vs Temperature - "X" Current Limit vs Temperature V = 18V Temperature DSON ...

Page 6

Typical Performance Characteristics ("X"), µH ("Y"), and T = 25˚C, unless specified otherwise. (Continued) A Line Regulation - "X" 1.5V 500mA OUT OUT Line Regulation - "X" 3.3V 500mA ...

Page 7

Block Diagram Application Information THEORY OF OPERATION The LM2736 is a constant frequency PWM buck regulator IC that delivers a 750mA load current. The regulator has a preset switching frequency of either 550kHz (LM2736Y) or 1.6MHz (LM2736X). These high frequencies ...

Page 8

Application Information current. Therefore recommended that V greater than 2.5V above V for best efficiency should not exceed the maximum operating limit of 5.5V. SW > > 5.5V V – V 2.5V for best performance. ...

Page 9

Application Information FIGURE 5. Boost Voltage Supplied from the Shunt Zener ENABLE PIN / SHUTDOWN MODE The LM2736 has a shutdown mode that is controlled by the enable pin (EN). When a logic low voltage is applied ...

Page 10

Design Guide (Continued) The LM2736 operates at frequencies allowing the use of ceramic output capacitors without compromising transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing output ripple. See the output capacitor section for more details on calculating ...

Page 11

Design Guide (Continued) OUTPUT VOLTAGE The output voltage is set using the following equation where R2 is connected between the FB pin and GND, and R1 is connected between V and the FB pin. A good value for R2 O ...

Page 12

LM2736X Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 6.3V, X5R C2, Output Cap 10µF, 6.3V, X5R C3, Boost Cap 0.01uF, 16V, X7R D1, Catch Diode 0.3V F D2, Boost Diode ...

Page 13

LM2736X Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 25V, X7R C2, Output Cap 22µF, 6.3V, X5R C3, Boost Cap 0.01µF, 16V, X7R D1, Catch Diode 0.34V Schottky 1A, 30VR F @ D2, Boost ...

Page 14

LM2736X Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 25V, X7R C2, Output Cap 22µF, 6.3V, X5R C3, Boost Cap 0.01µF, 16V, X7R C4, Shunt Cap 0.1µF, 6.3V, X5R D1, Catch Diode 0.4V D2, ...

Page 15

LM2736X Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 25V, X7R C2, Output Cap 22µF, 6.3V, X5R C3, Boost Cap 0.01µF, 16V, X7R D1, Catch Diode 0.4V Schottky 1A, 30VR F D2, Boost Diode ...

Page 16

LM2736X Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 25V, X7R C2, Output Cap 22µF, 16V, X5R C3, Boost Cap 0.01µF, 16V, X7R D1, Catch Diode 0.4V D2, Boost Diode 1V F D3, Zener ...

Page 17

LM2736Y Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 6.3V, X5R C2, Output Cap 22µF, 6.3V, X5R C3, Boost Cap 0.01µF, 16V, X7R D1, Catch Diode 0.3V Schottky 1A, 10VR F @ D2, Boost ...

Page 18

LM2736Y Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 25V, X7R C2, Output Cap 22µF, 6.3V, X5R C3, Boost Cap 0.01µF, 16V, X7R D1, Catch Diode 0.34V D2, Boost Diode 0.6V L1 10µH, 1.6A, ...

Page 19

LM2736Y Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 25V, X7R C2, Output Cap 22µF, 6.3V, X5R C3, Boost Cap 0.01µF, 16V, X7R C4, Shunt Cap 0.1µF, 6.3V, X5R D1, Catch Diode 0.4V Schottky ...

Page 20

LM2736Y Circuit Examples Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 25V, X7R C2, Output Cap 22µF, 6.3V, X5R C3, Boost Cap 0.01µF, 16V, X7R D1, Catch Diode 0.4V D2, Boost Diode 1V F D3, Zener ...

Page 21

LM2736Y Circuit Examples V Part ID Part Value U1 750mA Buck Regulator C1, Input Cap 10µF, 25V, X7R C2, Output Cap 22µF, 16V, X5R C3, Boost Cap 0.01µF, 16V, X7R D1, Catch Diode 0.4V Schottky 1A, 30VR F D2, Boost ...

Page 22

Physical Dimensions inches (millimeters) unless otherwise noted National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and ...

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