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Timing capacitor of L6699

Question asked by Liu.wen_chin on Feb 3, 2017

Hi, everyone


I encounter a problem about L6699.

The sch of L6699 is shown as below.


I'm testing in open circuit, so thePC817 is open and all other parameters as shown in the figure.


1.The delay is disabled.

2.STBY(I'm wrong with stay) is equivalent to short with RFmin.

3.ISEN is biased with 0.6V.

4.LINE is pull-up to VCC with 100 kohm.

5.DIS is disabled as well.


the Fmin set to be 150 kHz and Fstart is set to be 230~240 kHz.


Board test result with every pin voltage is below:

1.CSS      2V


3.CF         0V

4.RFmin   2V

5.STBY    2V

6.ISEN     0.7V

7.LINE      6.1V

8.DIS        0V



It seems that the L6699 can work, but the timing capacitor doesn't charge and discharge.

I replace L6699 with L6599A is work.

Are my parameters wrong? or there is something with fatal problem?



I found there are someone has the same question.

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