IR3598MPBF datasheet(15/20 Pages) IRF

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Dual/Doubler Interleaved MOSFET Driver

October 27, 2011 | FINAL | V1.09

IR3598

GENERAL DESCRIPTION

The IR3598 contains two high-efficiency, fast High and

Low side MOSFET drivers with large source and sink

current capability. It can reliably drive the external

high- and low-side N-channel MOSFETs with large input

capacitance at switching frequencies up to 1MHz.

The patented IR Active Tri-Level (ATL) feature allows

complete control over enable and disable of both MOSFETs

using the PWM input signal from the controller. The timing

and voltage levels of ATL are shown in Figure 6.

Each IR3598 can be operated to drive two independent

pairs of MOSFETs in one of two operating modes which are

dual mode and doubler mode. In dual mode, two

independent PWM inputs control two separate and

independent gate drive outputs. Each driver functions in a

similar way to a single high-low MOSFET driver such as the

CHL8515. In doubler mode, the two independent drivers

are controlled by a single input signal at PWM1.

In normal switching modes, they operate 180° out of phase

with each other. The phase modes for dual and doubler

are shown in Figure 8. Detailed timing diagrams can be

seen in Figures 9 and 10.

During normal operation the PWM transitions between

low and high voltage levels to drive the low- and high-side

MOSFETs. The PWM signal falling edge transition to a low

voltage threshold initiates the high side driver turn off

after a short propagation delay, tPDL(HS). The dead time

control circuit monitors the High Gate signals and switch

voltages to ensure the high side MOSFET is turned off

before the Low Gate voltages are allowed to rise to turn

on the low-side MOSFET.

The PWM rising edge transition through the high-side turn

on threshold, initiates the turn off of the low-side MOSFET

after a small propagation delay, tPDL(LS). The adaptive dead

time circuit provides the appropriate dead time by

determining if the falling Low Gate voltage threshold has

been crossed before allowing the High Gate voltage to rise

and turn on the high-side MOSFET, tPDH(HS).

THEORY OF OPERATION

POWER-ON RESET (POR)

The IR3598 incorporates a power-on reset feature.

This ensures that both the high and low side output drivers

are made active only after the device supply voltage Vcc

and Vdrive both have exceeded a certain minimum

operating threshold. The Vcc and Vdrive supplies are

monitored and both the drivers are set to the low state,

holding both external MOSFETs off. Once both Vcc and

VDRV cross the rising POR threshold, the IR3598 (if in IR

ATL mode) is reset and the outputs are held in the low

state until a transition from tri-state to active operation is

detected at the PWM input. For Tri-state mode, the POR

operation is the same except the driver does not look for

an input tri-state before functioning. During normal

operation the drivers continue to remain active until the

Vcc falls below the falling POR threshold.

INTEGRATED BOOTSTRAP DIODE

The IR3598 features an integrated bootstrap diode to

reduce external component count. This enables the IR3598

to be used effectively in cost and space sensitive designs.

The bootstrap circuit is used to establish the gate voltage

for the high-side driver. It consists of a diode and capacitor

connected between the SW and BOOT pins of each device.

Integrating the diodes within the IR3598, results in the

need for an external boot capacitor only. The bootstrap

capacitor is charged through the diode and injects this

charge into the high-side MOSFET input capacitance when

PWM signal goes high.

IR ACTIVE TRI-LEVEL (ATL) PWM INPUT SIGNAL

The IR3598 gate drivers are driven by a patented active

tri-level PWM control signal provided by the IR digital

PWM controllers. During normal operation, the rising and

falling edges of the PWM signal transitions between 0V

and 1.8V to switch the LO_GATE and HI_GATE. To force

both driver outputs low simultaneously, the PWM signal

crosses a tri-state voltage level higher than the tri-state

HI_GATE threshold. This threshold based tri-state results in

a very fast disable for both the drivers, with only a small

tri-state propagation delay. MOSFET switching resumes

when the PWM signal falls below the tri-state threshold

into the normal operating voltage range.

IR3598MPBF Datasheet(PDF) 15 Page - International Rectifier

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