TPS26600-02EVM: QUESTION ON tiducc7 SURGE TEST

user6001565

Part Number: TPS26600-02EVM

Hi Sir:

on page 17 of TIDUCC7.PDF, the surge test condition is 500V, 2ohm, 8/20uS, Vin=24V, L-N coupling; the peak surge current is around 200A( (500-100)/2)

the input TVS is D2(SMCJ28CA, ON PAGE 19); the max reverse voltage of SMCJ28CA is 45.4V at IRSM=33.1A;

the figure 17 shows that the input voltage is clamped to around 40V during the surge, it doesn't add up, how can input voltage be clamped by SMCJ28CA to 40V for 500V, 2ohm , 8/20us L/N surge?

over 5 years ago

0 Lokesh Ghulyani over 5 years ago

TI__Expert 8630 points

Hello,

We are looking into this and will get back in couple of days.

0 Lokesh Ghulyani over 5 years ago in reply to Lokesh Ghulyani

TI__Expert 8630 points

Hello user6001565 ,

The clamping voltage rating and Ipp of SMCJ28CA are specified for 10x1000 us pulse whereas the pulse used for TIDUCC7 is 8x20us as IEC61000-4-5 standard.

As per Fig 2 in datasheet of SMCJ28CA, the diode has higher Peak pulse power rating for pulse with lower width (half time). So, for 8x20us pulse, SMCJ diode will have different clamping voltage and Ipp.

0 user6001565 over 5 years ago in reply to Lokesh Ghulyani

Prodigy 80 points

Hi Lokesh:

just want to be clear, is 8/20us here current surge pulse, or 500V 1.2/50us voltage surge pulse with 2ohm/18uf coupling network?

if it's 500V 2ohm/18uf voltage surge, how much peak pulse current would it be for SMCJ28 as the main clamping device?

thanks

Sean

0 Lokesh Ghulyani over 5 years ago in reply to user6001565

TI__Expert 8630 points

Hello Sean,

For 500V/2-Ohm surge pulse, the peak current in TVS[SMCJ28CA] would be ~230A.

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TPS26600-02EVM: QUESTION ON tiducc7 SURGE TEST