Synchronous Buck MOSFET Driver

IXYS

Copyright © IXYS CORPORATION 2004

IXS839 / IXS839A / IXS839B

Features:

• Logic Level Gate Drive Compatible

• 2A Source, 4A Sink Peak Drive Current

• Programmable High-Side Driver Turn-on Delay

• Supports Floating Voltage for Top Driver Up to

24V

• IXS839/839B: Undervoltage Lockout

• IXS839A/B: Output Shutdown, Low Side

Shutdown Inputs

• 10µA Shut Down Current

• 2mA Quiescent Current (Non- Switching)

• Bootstrapped High Side Driver

• Cross-Conduction Protection

Applications:

• Multiphase Desktop CPU Supplies

• Mobile CPU Core Voltage supplies

• High Current / Low Voltage DC/DC

Synchronous Buck Converters

General Description

The IXS839/IXS839A/IXS839B are 2A Source / 4A

Sink Synchronous Buck MOSFET Drivers. These

Synchronous Buck MOSFET Drivers are specifically

designed to drive two N-channel power MOSFETs

in a synchronous buck converter. The High-Side

driver is powered via a bootstrapped power

connection. The driver is capable of 20ns High-Side

output, and 18ns Low-Side output transition times

driving a 3000pF load.

The

IXS839

and

IXS839B

incorporate

an

undervoltage lockout to prevent unintentional gate

drive output during low voltage conditions. The

IXS83A/B include External Shutdown and Low-Side

Drive Shutdown features. Simultaneous shutdown

of both outputs prevents rapid output capacitor

discharge. The high-side turn-on delay is adjustable

with an external capacitor added at the DLY pin.

The IXS839/839A/839B are designed to operate

over a temperature range of -40°C to +85°C. The

IXS839 is available in an 8-Lead SOIC, the

IXS839A and the IXS839B in a 10-pin QFN.

Figure 1. IXS839 Functional Block Diagram

Figure 2. IXS839A Functional Block Diagram

and General Application Circuit

and General Application Circuit

UVLO

OVERLAP

PROTECTION

CIRCUIT

CDLY

DLY

PWM

2

3

VDD

BST

HGD

SW

LGD

PGND

CBST

VIN

5V

DBST

4

1

8

7

5

6

VOUT

Q1

Q2

OVERLAP

PROTECTION

CIRCUIT

CDLY

DLY

7

VDD

BST

HGD

SW

LGD

PGND

CBST

VIN

5V

DBST

8

3

2

1

9

10

LSD

6

PWM

5

4

SD

VOUT

Q1

Q2