Version 2.0

5

1 Jul 2002

TDA 4605-2

Pin Definitions and Functions

Pin No.

Function

1

Information Input Concerning Secondary Voltage. By comparing the

regulating voltage - obtained from the regulating winding of the transformer - with

the internal reference voltage, the output impulse width on pin 5 is adjusted to the

load of the secondary side (normal load, overload, short-circuit, no load).

2

Information Input Regarding the Primary Current. The primary current rise in

the primary winding is simulated at pin 2 as a voltage rise by means of external

RC-circuit. If a voltage level is reached which is derived from the control voltage

at pin 1, the output impulse at pin 5 is terminated. The RC-circuit is used to set

the maximum power of the foldback point.

3

Input for Primary Voltage Monitoring: In the normal operation

between the thresholds

starts at

4

Ground

5

Output: Push-pull output for charging or discharging the gate capacity of the

power MOSFET-transistor.

6

Supply Voltage Input. From the voltage at pin 6 a stable internal reference

voltage

supply voltage detector are derived. If

reference voltage will be switched off if

enable, for

7

Input for Soft-Start and Integrator Circuit. The capacitor connected to ground

causes a slow increase of the duration of the output pulse during start-up and an

integrating response of the control amplifier.

8

Input for the Feedback of the Oscillator. After the oscillations of the SMPS

started, every transition of the feedback voltage through zero (falling edge)

triggers an output pulse at pin 5. The trigger threshold is at + 50 mV typical.