IR1150IPBF datasheet(7/16 Pages) IRF

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IR1150(S)/IR1150I(S)(PbF)

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General Description

The µPFC IR1150 is intended for boost converters for

power factor correction operating at a fixed frequency in

continuous conduction mode. The IC operates with two

loops; an inner current loop and an outer voltage loop.

The inner current loop is fast, reliable and does not

require sensing of the input voltage in order to create a

current reference.

This inner current loop sustains the sinusoidal profile of

the average input current based on the dependency of

the pulse width modulator duty cycle on the input line

voltage in order to determine the analogous input line

current. Thus, the current loop uses the embedded

input voltage signal to control the average input current

to follow the input voltage.

The IR1150 enables excellent THD performance. In

light load conditions, a small distortion occurs at zero-

crossing due to the finite boost inductance but this is

negligible and well within EN61000-3-2 Class D

specifications.

The outer voltage loop controls the DC bus voltage.

This voltage is fed into the voltage error amplifier to

control the slope of the integrator ramp and sets the

amplitude of the average input current.

The two loops combine to control the amplitude, phase

and shape of the input current, with respect to the input

voltage, giving near-unity power factor.

The IC is designed for robust operation and provides

protection from system level over current, over voltage,

under voltage, and brownout conditions.

IC Supply

The UVLO circuit monitors the VCC pin and maintains the

gate drive signal inactive until the VCC pin voltage

reaches the UVLO turn on threshold, (VCC ON). As soon as

the VCC voltage exceeds this threshold, provided that the

VFB pin voltage is greater than 20%VREF, the gate drive

will begin switching (under Soft Start) and increase the

pulse width to its maximum value as demanded by the

output voltage error amplifier. If the voltage on the VCC

pin falls below the UVLO turn off threshold, (VCC UVLO), the

IC turns off, gate drive is terminated, and the turn on

threshold must again be exceeded in order to re-start the

process and move into Soft Start mode.

Soft Start

Soft Start controls the rate of rise of the output voltage

error amplifier in order to obtain a linear control of the

increasing duty cycle as a function of time. The Soft Start

time is controlled by voltage error amplifier compensation

components selected, and is user programmable based

on desired loop crossover frequency.

Frequency Select

The switching frequency of the IC is programmable by an

external resistor at the FREQ pin. The design

incorporates min/max restrictions such that the minimum

and maximum operating frequency fall within the range of

50-200kHz.

Gate Drive

The gate drive is a totem pole driver with 1.5A capability.

If higher currents are required, additional external drivers

can be used.

IR1150IPBF Datasheet(PDF) 7 Page - International Rectifier

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