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UCC27524: OUTB voltage negative spike

Part Number: UCC27524

Hi Team, 

please kindly check below questions. 

1. customer use short gnd line to test the voltage stress and find there is -4V/1.22ns spike. Please kindly check if it is OK. 

Test point is as in red circle. 

2. in datasheet, there is -2V/<200ns spec, why is there such -2V spec?  

3. in above waveform, is the 1ns spike generated by internal parasitic inductance? 

Thanks. 

BRs

Given 

  • Hello Given,

    Thanks for reaching out.

    1. From the waveform you shared, It looks like the falling edge undershoot a result of the strong peak sink current (5-A) out of the CH-A driver which is explained by the short duration of the pulse therefore this should not be a reason for concern. I assume the measurement is done through tip & barrel method using scope probes short lead inductance, please confirm.

    2. The -2V/<200ns specifies the stress levels that, if exceeded, may cause permanent damage to the device. However, these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Also, exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 

    3. The 1ns for this case could seems to be from the strong peak current out of the driver during the falling edge. "Weaker" driver will not have such pulse as internal pulldown FET might not have capability of turning off gate fast enough. In some cases, it may also may as a result of package lead inductance and other internal bond wire parasitic.

    Regards,

    -Mamadou 

  • Hi Mamadou,

    Thanks for your reply.

    Regarding #1, yes, it's measured use tip& barrel method. So the short negative spike is not a concern, right? Thanks.

    BRs

    Given

  • Given,

    Correct, no significant risk with 1.2ns undershoot at -4V.

    Regards,

    -Mamadou