LDP01-35AY ISO16750-2 pulse

[Mvon .1]

Dear sir or madam,

we are using the LDP01-35AY twice in our design for input protection as given in ISO 7637-2 and ISO 16750-2. Unfortunately the load dump pulse destroys our input circuit. I did an extrapolation of the "Safe Operation Mode" of the diode as given in the datasheet page 4. By this I thought the diode is suitable to protect from Load Dump Pulses with 150 V at td = 400 ms and 180 V at td = 150 ms. We tested 150 V with td = 400 ms and the diode immediately was detroyed. Do you have any other parts? Why does the diode get destroyed? We need to be compliant with the ISO 16750-2 therefore 150 V at td = 400 ms is the minimum for us.

Best regards

Marc

[FGUIT]

Dear Marc,

We tested LDP01-35AY, with 150V at td=400ms, and 180V at td=150ms, both with Ri=4ohm, according to ISO-16750-2 standard definition (i.e. 150V or 180V is the peak voltage of the surge, see figure 9 on LDP01 datasheet): LDP01 is OK after surges.

Can you verify that you used the same surge definition?

indeed, there is also the ISO 7637-2 surge definition (i.e. 150V or 180V is added to battery voltage, see figure 5 of LDP01 datasheet), so for example, with battery = 24V, peak surge voltage = 24V + 150V = 174V or 24V + 180V = 204V. In this case, the peak surge voltage is higher than the surge that LDP01 can withstand.

We used a TESEQ LD5550 to perform load dump surge tests.

Best regards.

Fabrice.

[Mvon .1]

Dear Fabrice,

thank you very much for your effort. We asked the emc laboratory and indeed they tested the wrong pulse surge definition. We will start the test again according to ISO-16750-2 and get back to you.

Best regards

Marc

[Mvon .1]

Dear Fabrice,

we now verified the measurement and the LDP01-35AY withstands the pulse sufficiently. Thank you very much for your help!

Best regards

Marc

[FGUIT]

Dear Marc,

You're welcome.

Best regards.

Fabrice.