Q67000-A8299 View Datasheet(PDF) - Siemens AG

Part Name

Description

Manufacturer

Q67000-A8299

Power Factor Controller IC for High Power Factor and Active Harmonic Filtering

Siemens AG 

TDA 4817

Discontinuous Operation Mode with Variable Frequency

The TDA 4817 works in a discontinuous operation mode with variable frequency.

The principle of a freely oscillating controller exploits the physical relationship between current and

voltage at the boost converter choke. The current in the semiconductors flows in a triangular shape.

This is only when the current in the boost converter diode has gone to zero that the transistor goes

conductive. This arrangement does away with the diode’s power-squandering reverse currents.

If triangular currents flow continuously through the boost converter choke the input current

averaged over a high-frequency period is exactly half the peak of the high-frequency choke current.

If the peak values of the choke current are located along an envelope curve that is proportional to

a sinusoidal low- frequency input voltage, the input current available after smoothing in an RFI filter

is sinusoidal.

Semiconductor Group

9

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