IR3087MPBF datasheet(6/35 Pages) IRF

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IR3087PBF

PIN DESCRIPTION

PIN#

PIN SYMBOL

PIN DESCRIPTION

RMPIN+

Non-inverting input to Ramp Comparator

RMPIN-

Inverting input to Ramp Comparator

HOTSET

Inverting input to VRHOT comparator. Connect resistor divider from VBIAS to LGND

to program VRHOT threshold. Diode or thermistor may be substituted for lower

resistor for enhanced/remote temperature sensing.

VRHOT

Open Collector output of the VRHOT comparator which drives low if IC junction

temperature exceeds the user programmable limit. Connect external pull-up.

ISHARE

Output of the Current Sense Amplifier and input to the Share Adjust Error Amplifier.

Voltage on this pin is equal to V(DACIN) + 34 * [V(CSIN+) – V(CSIN-)]. Connecting

ISHARE pins together creates a Share Bus enabling current sharing between Phase

ICs. The Share bus is also used by the Control IC for voltage positioning and Over-

Current protection.

SCOMP

Compensation for the Current Share control loop. Connect a capacitor to ground to

set the control loop’s bandwidth.

EAIN

PWM comparator input from the error amplifier output of Control IC. Both Gate

Driver outputs drive low if the voltage on this pin is less than 88% of V(DACIN).

PWMRMP

PWM comparator ramp input. Connect a resistor from this pin to the converter input

voltage and a capacitor to LGND to program the PWM ramp.

LGND

Signal ground and IC substrate connection

VCC

Power for internal circuitry

VCCL

Power for Low-Side Gate Driver

GATEL

Low-Side Gate Driver Output and input to GATEH non-overlap comparator

PGND

Return for Gate Drivers

GATEH

High-Side Gate Driver Output and input to GATEL non-overlap comparator

VCCH

Power for High-Side Gate Driver

CSIN+

Non-inverting input to the Current Sense Amplifier

CSIN-

Inverting input to the Current Sense Amplifier and non-inverting input to the OVP

comparator

OPTIPHS

Input to the Opti-Phase

TM Comparator. If the voltage on this pin exceeds the voltage

on the ISHARE pin minus the voltage on the DACIN pin the GATEX pins will drive

low. Connect external resistor divider to BIASIN, OPTIPHS and LGND to program,

or connect to BIASIN to disable.

DACIN

Reference voltage input from the Control IC and also inverting input to the OVP

comparator. Current sensing and PWM operation referenced to this pin.

BIASIN

System reference voltage for internal circuitry

Page 6 of 35

1/31/05

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