Q67000-A9377(2000) Ver la hoja de datos (PDF) - Infineon Technologies

Número de pieza

componentes Descripción

Fabricante

Q67000-A9377
(Rev.:2000)

Controller for Switch Mode Power Supplies Supporting Low Power Standby and Power Factor Correction

Infineon Technologies 

TDA 16846

TDA 16847

Fixed Frequency and Synchronization Circuit SYN (Pin 7)

Figure 11 shows the Fixed Frequency and Synchronization Circuit. The circuit is

disabled when Pin 7 is not connected. With R7 and C7 at Pin 7 the circuit is working. C7

is charged fast by approx. 1 mA and discharged slowly by R7 (Figure 11). The power

transistor is switched on at beginning of the charge phase. The switching frequency is

(charge time ignored)

:

f ≈ ----1--,-1---8----

R7 × C7

When the oscillator circuit is working the Fold Back Point Correction is disabled (not

necessary in fixed frequency mode). “Switch on” is only possible when a “zero crossing”

has occurred at Pin 3, otherwise “switch-on” will be delayed (Figure 12).

External

Internal

SYN 7

OP1

OP1OUT

R7

C7

30

kΩ

15 kΩ

5V

Logic

75 kΩ

LO

OUT 13

RZI 3

Zero Crossing Signal

AES02656

Figure 11 Synchronization and Fixed Frequency Circuit

Data Sheet

14

2000-01-14

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