THVD1550: Why does it need series resistors 10 ohm in signal trace?

Aaron Chen (FAE)

Intellectual 1310 points

Part Number: THVD1550

Hi Expert,

May I know why does this device need R1,R2(=10ohm) in series with signal trace?

Thanks

BR,

Aaron Chen

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 243980 points

These resistors reduce the current in case of transients/surges; see sections 10.2.1.5 and 12.1.7. You need them only if such disturbances can happen in your environment.

0 Aaron Chen (FAE) over 1 year ago in reply to Clemens Ladisch

TI__Intellectual 1310 points

Hi Clemens,

How does it work?

How could I determine this resistance?

BR,

Aaron Chen

Thanks

0 Clemens Ladisch over 1 year ago in reply to Aaron Chen (FAE)

Guru 243980 points

This depends on the actual voltage of the surges and on the clamping voltage of the TVS. But the former is hard to estimate, and the resistance must not be so high as to attenuate the signal, so 10 Ω is a value that is typically chosen.

0 Parker Dodson over 1 year ago in reply to Aaron Chen (FAE)

TI__Mastermind 43516 points

Hi Aaron,

Clemens in correct - it is dependent on surge values - but a typical resistance, if series resistances are used, is about 10 ohms. You don't want too go to much higher or the DC losses could bring too much attenuation. These resistors, as mentioned, aren't always required, but if used should be relatively small.

If you have any other questions please let me know!

Best,

Parker Dodson

Interface

Interface forum

THVD1550: Why does it need series resistors 10 ohm in signal trace?