AN1439

Design specification

9/17

prevents improper Power MOSFET's turn-on, due to signal bouncing on the pin, by pulling

secondary winding - or D7 failing short - causes an intermittent operation with an even lower

level of power throughput.

Board evaluation: getting started

connector M1 (at the bottom left-hand corner). Should one want to use a high-voltage DC

source, remember that the startup charge pump would not work and a dropping resistor

would be needed to let the L6565 start.

The 15 VDC output (connector M2) is located close to the bottom right-hand corner and will

be connected to the load. If an electronic load is going to be used in CC mode, make sure

that the voltage which the load starts sinking current at is > 1 V or use CR mode if this

cannot be set, otherwise the board may not start up at maximum load. This happens

trigger QR operation (refer to 2.: "L6565 Quasi-Resonant Controller" (AN1326).) Before that,

the converter runs at the frequency of the internal starter, with a much lower power

reach the minimum amplitude required, QR operation cannot take place and the system

cannot start up.

Caution:

Like in any offline circuit, extreme caution must be used when working with the

application board because it contains dangerous and lethal potentials. The

application must be tested with an isolation transformer connected between the AC

mains and the input of the board to avoid any risk of electrical shock.

Board evaluation: bench results and significant waveforms

Table 5, 6, and 7 summarize the results of some bench evaluations. A number of waveforms

under different load and line conditions are shown for the user's reference.

Table 5.

STEVAL-ISC001V1: typical performance

Parameter

Value

Unit

14.924

V

60

kHz

214

kHz

1

mV

55

mV

10

mV

< 5

mV

85

%

0.6

W