LM61435-Q1: 42 V automotive load dump

Hi Henry,

There is standard define the load dump waveform, but no standard define how to clamp the over voltage to certain level, LM61435 can be surviving if the voltage peak is clamped below 42V,  for a 100V converter, you only need to clamp it below 100V with lower protection circuit cost

B R

Andy

Hi Sir,

My customer has some questions as below.

Q1: Supports to 42V load dump described from the datasheet, its meaning is that designer also have to design load dump protection circuit in front of LM61435,

whatever level of load dump will be tested? is it no specific test requirement of load dump such as voltage level, duration time?

Q2: if yes, I am a little bit confused with it, why LM61435 can support load dump?

Q3: or if the voltage peak level is below 42V, load dump protection circuit can be removed?

Hi Henry,

Pls refer to ISO7637 for load dump waveform definition. the peak voltage will be 100V in 12V system.

So normally there should be protection circuit in front of LM61435 to clamp the voltage below 42V. unless there is clamping circuit installed to the alternator, which limits the voltage to a more manageable level of 30-38V.

B R

Andy.

Hi Andy,

Therefore, the supports 42V load dump from LM61435 description might be considered to design if our test standard level is under 38V or more. the LM61435 would be safe, right?