Infineon Technologies

preliminary

ICE1PD265G

Infineon Tech

PCI Group

10.09.01

5

Multiplier

The one quadrant multiplier regulates the gate driver with respect of the DC output voltage and the

AC half wave rectified input voltage. Both inputs are designed to achieve good linearity over a wide

dynamic range to represent an AC line free from distortion. Special efforts are made to assure uni-

versal line applications with respect to a 90 to 270 V AC range.

The multiplier output is internally clamped at 1.0V. So the MOSFET is protected against critical

operating during start up.

Current sense comparator, LEB and RS Flip-Flop

An external sense resistor transferes the source current of the MOSFET into a sense voltage.The

multiplier output voltage is compared with this sense voltage.

To protect the current comparator input from negative pulses a current source is inserted which

sends current out of the ISENSE pin every time when ISENSE is falling below ground potential. The

switch-on current peak of the MOSFET is blanked out via a resistor-capacitor circuit with a blanking

time of typically 220ns. Therefore better THD is achieved at low load conditions.

The RS Flip-Flop ensures that only one single switch-on and switch-off pulse appears at the gate

drive output during a given cycle (double pulse suppression).

Zero Current Detector

The zero current detector senses the inductor current via an auxiliary winding and ensures that the

next on-time of the MOSFET is initiated immediately when the inductor current has reached zero.

This diminishes the revers recovery losses of the boost converter diode. The MOSFET is switched

off when the voltage drop of the shunt resistor reaches the voltage level of the multipler output. So

the boost current waveform has a triangular shape and there are no deadtime gaps between the

cycles. This leads to a continuous AC line current limiting the peak current to twice of the average

current.

To prevent false tripping the zero current detector is designed as a Schmitt-Trigger with a hysteresis

of 0.5V. An internal 5V clamp protects the input from overvoltage breadkdown, a 0.6V clamp pre-

vents substrate injection. An external resistor has to be used in series with the auxiliary winding to

limit the current through the clamps.

Restart Timer

If the MOS is off for more than 150us a restart impulse is generated by the restart timer.