LM2722
LM2722 High Speed Synchronous/Asynchronous MOSFET Driver
Literature Number: SNVS169B
LM2722
OBSOLETE
September 23, 2011
High Speed Synchronous/Asynchronous MOSFET Driver
General Description
The LM2722, part of the LM2726 family, is designed to be
used with multi-phase controllers. This part differs from the
LM2726 by changing the functionality of the SYNC_EN pin
from a whole chip enable to a low side MOSFET enable. As
a result, the SYNC_EN pin now provides control between
Synchronous and Asynchronous operations. Having this con-
trol can be advantageous in portable systems since Asyn-
chronous operations can be more efficient at very light loads.
The LM2722 drives both top and bottom MOSFETs in a push-
pull structure simultaneously. It takes a logic level PWM input
and splits it into two complimentary signals with a typical 20ns
dead time in between. The built-in cross-conduction protec-
tion circuitry prevents the top and bottom FETs from turning
on simultaneously. The cross-conduction protection circuitry
detects both the driver outputs and will not turn on a driver
until the other driver output is low. With a bias voltage of 5V,
the peak sourcing and sinking current for each driver of the
LM2722 is typically 3A. In an SO-8 package, each driver is
able to handle 50mA average current. Input UVLO (Under-
Voltage-Lock-Out) forces both driver outputs low to ensure
proper power-up and power-down operation. The gate drive
bias voltage needed by the high side MOSFET is obtained
through an external bootstrap. Minimum pulse width is as low
as 55ns.
Features
■Synchronous or Asynchronous Operation
■Adaptive shoot-through protection
■Input Under-Voltage-Lock-Out
■Typical 20ns internal delay
■Plastic 8-pin SO package
Applications
■Driver for LM2723 Intel Mobile Northwood CPU core
power supply.
■High Current DC/DC Power Supplies
■High Input Voltage Switching Regulators
■Fast Transient Microprocessors
Typical Application
20028901
Note: National is an Intel Mobile Voltage Positioning (IMVP) licensee.
© 2011 National Semiconductor Corporation 200289 www.national.com
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722 High Speed Synchronous/Asynchronous MOSFET Driver
Connection Diagram
8-Lead Small Outline Package
20028902
Top View
Ordering Information
Order Number Package Type NSC Package Drawing Supplied As
LM2722 LM2722M M08A 95 Units/Rail
LM2722MX 2500 Units/Reel
Pin Descriptions
Pin Name Function
1 SW Top driver return. Should be connected to the common node of top and bottom FETs
2 HG Top gate drive output
3 CBOOT Bootstrap. Accepts a bootstrap voltage for powering the high-side driver
4 PWM_IN Accepts a 5V-logic control signal
5 SYNC_EN Low gate Enable
6 VCC Connect to +5V supply
7 LG Bottom gate drive output
8 GND Ground
www.national.com 2
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722
Block Diagram
20028904
3 www.national.com
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
VCC 7.5V
CBOOT 42V
CBOOT to SW 8V
SW to PGND 36V
Junction Temperature +150°C
Power Dissipation
(Note 2) 720mW
Storage Temperature −65° to 150°C
ESD Susceptibility
Human Body Model (Note 3) 1kV
Soldering Time, Temperature 10sec., 300°C
Operating Ratings (Note 1)
VCC 4V to 7V
Junction Temperature Range −40° to 125°C
Electrical Characteristics
VCC = CBOOT = 5V, SW = GND = 0V, unless otherwise specified. Typicals and limits appearing in plain type apply for TA = TJ =
+25°C. Limits appearing in boldface type apply over the entire operating temperature range.
Symbol Parameter Condition Min Typ Max Units
POWER SUPPLY
Iq_op Operating Quiescent Current PWM_IN = 0V 190 300 µA
TOP DRIVER
Peak Pull-Up Current Test Circuit 1, Vbias = 5V, R =
0.1Ω
3.0 A
Pull-Up Rds_on ICBOOT = IHG = 0.7A 1.0 Ω
Peak Pull-down Current Test Circuit 2, Vbias = 5V, R =
0.1Ω
−3.2 A
Pull-down Rds_on ISW = IHG = 0.7A 0.5 Ω
t4Rise Time Timing Diagram, CLOAD = 3.3nF 17 ns
t6Fall Time 12 ns
t3Pull-Up Dead Time Timing Diagram 23 ns
t5Pull-Down Delay Timing Diagram, from PWM_IN
Falling Edge 27 ns
BOTTOM DRIVER
Peak Pull-Up Current Test Circuit 3, Vbias = 5V, R =
0.1Ω 3.2 A
Pull-up Rds_on IVCC = ILG = 0.7A 1.0 Ω
Peak Pull-down Current Test Circuit 4, Vbias = 5V, R =
0.1Ω 3.2 A
Pull-down Rds_on IGND = ILG = 0.7A 0.5 Ω
t8Rise Time Timing Diagram, CLOAD = 3.3nF 17 ns
t2Fall Time 14 ns
t7Pull-up Dead Time Timing Diagram 28 ns
t1Pull-down Delay Timing Diagram, from PWM_IN
Rising Edge 13 ns
LOGIC
Vuvlo_up Power On Threshold VCC rises from 0V toward 5V 43.7 V
Vuvlo_dn Under-Voltage-Lock-Out
Threshold
3.0 2.5 V
Vuvlo_hys Under-Voltage-Lock-Out
Hysteresis
0.7 V
VIH_EN SYNC_EN Pin High Input 2.4 V
VIL_EN SYNC_EN Pin Low Input 0.8 V
Ileak_EN SYNC_EN Pin Leakage
Current
EN = 5V −2 2µA
EN = 0V −2 2
www.national.com 4
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722
Symbol Parameter Condition Min Typ Max Units
ton_min Minimum Positive Input Pulse
Width
(Note 4)
55
ns
toff_min Minimum Negative Input Pulse
Width
(Note 5)
55
VIH_PWM PWM_IN High Level Input
Voltage
When PWM_IN pin goes high
from 0V 2.4
V
VIL_PWM PWM_IN Low Level Input
Voltage
When PWM_IN pin goes low from
5V 0.8
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating ratings are conditions under which the device operates
correctly. Operating Ratings do not imply guaranteed performance limits.
Note 2: Maximum allowable power dissipation is a function of the maximum junction temperature, TJMAX, the junction-to-ambient thermal resistance, θJA, and the
ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: PMAX = (TJMAX-TA) / θJA. The junction-to-
ambient thermal resistance, θJA, for the LM2722, it is 172°C/W. For a TJMAX of 150°C and TA of 25°C, the maximum allowable power dissipation is 0.7W.
Note 3: ESD machine model susceptibility is 100V.
Note 4: If after a rising edge, a falling edge occurs sooner than the specified value, the IC may intermittently fail to turn on the bottom gate when the top gate is
off. As the falling edge occurs sooner and sooner, the driver may start to ignore the pulse and produce no output.
Note 5: If after a falling edge, a rising edge occurs sooner than the specified value, the IC may intermittently fail to turn on the top gate when the bottom gate is
off. As the rising edge occurs sooner and sooner, the driver may start to ignore the pulse and produce no output.
5 www.national.com
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722
Timing Diagram
20028903
Test Circuits
20028905
Test Circuit 1
20028906
Test Circuit 2
20028907
Test Circuit 3
20028908
Test Circuit 4
www.national.com 6
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722
Typical Waveforms
20028913
FIGURE 1. Switching Waveforms of Test Circuit
20028914
FIGURE 2. When Input Goes High
20028915
FIGURE 3. When Input Goes Low
20028916
FIGURE 4. Minimum Positive Pulse
Application Information
MINIMUM PULSE WIDTH
In order for the shoot-through prevention circuitry in the
LM2722 to work properly, the pulses into the PWM_IN pin
must be longer than 55ns. The internal logic waits until the
first FET is off plus 20ns before turning on the opposite FET.
If, after a falling edge, a rising edge occurs sooner than the
specified time, toff_min, the IC may intermittently fail to turn on
the top gate when the bottom gate is off. As the rising edge
occurs sooner and sooner, the driver may start to ignore the
pulse and produce no output. This condition results in the
PWM_IN pin in a high state and neither FET turned on. To get
out of this state, the PWM_IN pin must see a low signal for
greater than 55ns, before the rising edge.
This will also assure that the gate drive bias voltage has been
restored by forcing the top FET source and Cboot to ground
first. Then the internal circuitry is reset and normal operation
will resume.
Conversely, if, after a rising edge, a falling edge occurs soon-
er than the specified miniumum pulse width, ton_min, the IC
may intermittently fail to turn on the bottom FET. As the falling
edge occurs sooner and sooner, the driver will start to ignore
the pulse and produce no output. This will result in the toff in-
ductor current taking a path through a diode provided for non-
synchronous operation. The circuit will resume synchronous
operation when the rising PWM pulses exceed 55ns in dura-
tion.
HIGH INPUT VOLTAGES OR HIGH OUTPUT CURRENTS
At input voltages above twice the output voltage and at higher
power levels, the designer may find snubber networks and
gate drive limiting useful in reducing EMI and preventing in-
jurious transients. A small resistor, 1Ω to 5Ω, between the
driver outputs and the MOSFET gates will slightly increase
the rise time and fall time of the output stage and reduce
switching noise. The trade-off is 1% to 2% in efficiency.
A series R-C snubber across in parallel with the bottom FET
can also be used to reduce ringing. Values of 10nF and
10Ω to 100Ω are a good starting point.
7 www.national.com
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722
Physical Dimensions inches (millimeters) unless otherwise noted
8-Lead Small Outline Package
NS Package Number M08A
www.national.com 8
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722
Notes
9 www.national.com
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:03
LM2722
Notes
LM2722 High Speed Synchronous/Asynchronous MOSFET Driver
For more National Semiconductor product information and proven design tools, visit the following Web sites at:
www.national.com
Products Design Support
Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench
Audio www.national.com/audio App Notes www.national.com/appnotes
Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns
Data Converters www.national.com/adc Samples www.national.com/samples
Interface www.national.com/interface Eval Boards www.national.com/evalboards
LVDS www.national.com/lvds Packaging www.national.com/packaging
Power Management www.national.com/power Green Compliance www.national.com/quality/green
Switching Regulators www.national.com/switchers Distributors www.national.com/contacts
LDOs www.national.com/ldo Quality and Reliability www.national.com/quality
LED Lighting www.national.com/led Feedback/Support www.national.com/feedback
Voltage References www.national.com/vref Design Made Easy www.national.com/easy
PowerWise® Solutions www.national.com/powerwise Applications & Markets www.national.com/solutions
Serial Digital Interface (SDI) www.national.com/sdi Mil/Aero www.national.com/milaero
Temperature Sensors www.national.com/tempsensors SolarMagic™ www.national.com/solarmagic
PLL/VCO www.national.com/wireless PowerWise® Design
University
www.national.com/training
THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION
(“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY
OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO
SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS,
IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS
DOCUMENT.
TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT
NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL
PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR
APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND
APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE
NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS.
EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO
LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE
AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR
PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY
RIGHT.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR
SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and
whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected
to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform
can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness.
National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other
brand or product names may be trademarks or registered trademarks of their respective holders.
Copyright© 2011 National Semiconductor Corporation
For the most current product information visit us at www.national.com
National Semiconductor
Americas Technical
Support Center
Email: support@nsc.com
Tel: 1-800-272-9959
National Semiconductor Europe
Technical Support Center
Email: europe.support@nsc.com
National Semiconductor Asia
Pacific Technical Support Center
Email: ap.support@nsc.com
National Semiconductor Japan
Technical Support Center
Email: jpn.feedback@nsc.com
www.national.com
200289 Version 3 Revision 3 Print Date/Time: 2011/09/23 15:04:04
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic."Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Audio www.ti.com/audio Communications and Telecom www.ti.com/communications
Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers
Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps
DLP®Products www.dlp.com Energy and Lighting www.ti.com/energy
DSP dsp.ti.com Industrial www.ti.com/industrial
Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical
Interface interface.ti.com Security www.ti.com/security
Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense
Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive
Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video
RFID www.ti-rfid.com
OMAP Mobile Processors www.ti.com/omap
Wireless Connectivity www.ti.com/wirelessconnectivity
TI E2E Community Home Page e2e.ti.com
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright ©2011, Texas Instruments Incorporated
