AN3142 datasheet(34/44 Pages) STMICROELECTRONICS

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L6563H: high voltage startup transition mode PFC

AN3142

34/44

Doc ID 17005 Rev 3

L6563H: high voltage startup transition mode PFC

The L6563H is a new current-mode PFC controller operating in transition mode (TM) which

embeds the same features existing in the L6563S with the addition of a high voltage startup.

Package and pin-out are different as shown in

Figure 21. Pin function is the same, in this

paragraph a detailed description of the HV startup system is given.

Figure 21.

L6563H and L6563S pin-out comparison

Figure 22 shows the internal schematic of the high-voltage startup generator. It is made up

of a high-voltage N-channel FET, whose gate is biased by a 15 M resistor, with a

temperature compensated current generator connected to its source.

The HV generator is physically located on a separate chip, made with BCD off-line

technology able to withstand 700 V, controlled by a low-voltage chip, where all of the control

functions reside.

Figure 22.

High-voltage startup generator: internal schematic

With reference to the timing diagram of

Figure 23, when power is first applied to the

converter the voltage on the bulk capacitor (Vin) builds up and, at about 80 V, the HV

generator is enabled to operate (HV_EN is pulled high) so that it draws about 1 mA. This

L6563H – SO16

L6563S – SO14

L6563H

15 M

Ω

GND

HVST ART

Vcc

Icharge

Vcc_OK

IHV

CONTR OL

HV_EN

AN3142 Datasheet(PDF) 34 Page - STMicroelectronics