TDA16847 데이터 시트보기 (PDF) - Infineon Technologies

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TDA16847

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

Infineon Technologies 

TDA 16846

TDA 16846-2

2

Functional Description

Start Up Behaviour (Pin 14)

When power is applied to the chip and the voltage V14 at Pin 14 (VCC) is less than the

upper threshold (VON) of the Supply Voltage Comparator (SVC), then the input current

I14 will be less than 100 µA. The chip is not active (off state) and driver output (Pin 13)

and control output (Pin 4) will be actively held low. When V14 exceeds the upper SVC

threshold (VON) the chip starts working and I14 increases. When V14 falls below the lower

SVC threshold (VOFF) the chip starts again from its initial condition. Figure 4 shows the

start-up circuit and Figure 5 shows the voltage V14 during start up. Charging of C14 is

done by resistor R2 of the “Primary Current Simulation” (see later) and the internal diode

D1, so no additional start up resistor is needed. The capacitor C14 delivers the supply

current until the auxiliary winding of the transformer supplies the chip with current

through the external diode D14.

It is recommended to apply a small RF snubber capacitor of e.g. 100 nF parallel to the

electrolytic capacitor at pin 14 as shown in the application circuits in Figures 15, 16 , and

17.

To avoid multiple pulses during start up in fixed frequency mode (danger of transformer

saturation), the IC works in freerunning mode until the pulses at pin 3 (RZI) exceed the

2.5 V threshold (only TDA 16846-2, TDA 16847-2).

Figure 4 Startup Circuit

Data Sheet

8

2003-07-31

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