Document
LM2722 High Speed Synchronous/Asynchronous MOSFET Driver
December 2001
LM2722 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 control can be advantageous in portable systems since Asynchronous 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 protection 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
n n n n n Synchronous or Asynchronous Operation Adaptive shoot-through protection Input Under-Voltage-Lock-Out Typical 20ns internal delay Plastic 8-pin SO package
Applications
n Driver for LM2723 Intel Mobile Northwood CPU core power supply. n High Current DC/DC Power Supplies n High Input Voltage Switching Regulators n Fast Transient Microprocessors
Typical Application
20028901
Note: National is an Intel Mobile Voltage Positioning (IMVP) licensee.
© 2001 National Semiconductor Corporation
DS200289
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LM2722
Connection Diagram
8-Lead Small Outline Package
20028902
Top View
Ordering Information
Order Number LM2722 Package Type LM2722M LM2722MX NSC Package Drawing M08A Supplied As 95 Units/Rail 2500 Units/Reel
Pin Description
Pin 1 2 3 4 5 6 7 8 Name SW HG CBOOT PWM_IN SYNC_EN VCC LG GND Function Top driver return. Should be connected to the common node of top and bottom FETs Top gate drive output Bootstrap. Accepts a bootstrap voltage for powering the high-side driver Accepts a 5V-logic control signal Low gate Enable Connect to +5V supply Bottom gate drive output Ground
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2
LM2722
Block Diagram
20028904
3
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LM2722
Absolute Maximum Ratings
(Note 1)
Storage Temperature ESD Susceptibility Human Body Model (Note 3) Soldering Time, Temperature
−65˚ to 150˚C 1kV 10sec., 300˚C
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