IR3537 datasheet(11/15 Pages) IRF

11 / 15 page

September 17, 2012 | FINAL | V1.11

IR3537

CHL8510

12V High Performance Gate Driver

supply voltage plus the HVCC voltage less the diode

forward voltage.

When the PWM signal goes low, the MOSFET is turned off

by pulling the MOSFET gate to the SWITCH voltage.

LOW-SIDE DRIVER

The IR3537/CHL8510 low-side driver is designed to drive

an external N-channel MOSFET referenced to ground at up

to 1MHz. The low-side driver is connected internally to the

LVCC supply voltage.

ADAPTIVE DEAD TIME ADJUSTMENT

In a synchronous buck configuration, dead time between

the turn off of one gate and turn on of the other is

necessary to prevent simultaneous conduction of the

external MOSFETS preventing a shoot-through condition

which would result in a short of the supply voltage to

ground. A fixed dead time does not provide optimal

performance across a variety of MOSFETs and board

layouts.

The IR3537/CHL8510 provides an ‘adaptive’ dead time

adjustment. This feature minimizes dead time which

maximizes efficiency. The ‘break before make’ adaptive

design is achieved by monitoring gate and SWITCH

voltages to determine OFF status of a MOSFET. It also

provides zero-voltage switching (ZVS) of the low-side

MOSFET with minimum current conduction through its

body-diode.

When the PWM is switching between 1.8V and 0V, its

falling edge transition from high to low will turn off the

high-side gate driver. The adaptive dead time circuit

monitors the HI_GATE and the SWITCH node voltages

during the high-side MOSFET turn off. When the HI_GATE

falls below 1.7V above the SWITCH node potential or the

SWITCH node voltage drops below 0.8V, the high-side

MOSFET is determined to be turned off, and the LO_GATE

turn-on is initiated. This turns on the external low-side

MOSFET. The rising edge transition of the PWM signal from

low to high voltage causes the low-side gate driver to turn

off. The adaptive circuit monitors the voltage at LO_GATE

and when it falls below 1.7V, the low-side MOSFET is

turned off, and the high-side MOSFET turn-on is initiated.

This turns on the external high-side MOSFET.

INDEPENDENT VARIABLE GATE VOLTAGE

The IR3537/CHL8510 features independent variable

gate voltages for both the high- and low-side drivers.

This enables implementation of the Variable Gate Drive

(VGD) feature in VR circuits using the IR multiphase

controllers to improve efficiency.

The voltage applied to the HVCC and LVCC pins of

IR3537/CHL8510 determines the gate voltage on the

external MOSFETs. These pins may be powered from

independent voltage sources or tied together to a common

voltage source. Variation in the gate voltage allows

efficiency to be optimized across the load current range by

trading off conduction and switching losses. Increasing the

voltage across a MOSFET gate, results in reduced Rdson

which lowers the MOSFET conduction losses, but also

raises the gate charge which increases the switching losses.

The voltage on each HVCC and LVCC pin, and thus the gate

drive voltage of the CHL8510, can be varied from 4.5V to

13.2V.

The International Rectifier’s digital multiphase controllers

provide a unique VAR_GATE output which varies inversely

with the VR output current. The VAR_GATE output is

designed to be used with an external circuit and provide

the optimum voltage across the IR3537/CHL8510’s HVCC

and LVCC pins for optimum system efficiency across the

load range.

IR3537 Datasheet(PDF) 11 Page - International Rectifier

IR3537 Datasheet(HTML) 11 Page - International Rectifier

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Datasheet Download

Link URL