THVD1420: Quick Question on Ios

Cameron Perl said:

Is Ios spec implying the need for the 10Ohm series resistors on A/B or something else? Are there internal protection that limits the current?

10 ohms is not required on the A/B lines.

The IoS spec comes from the RS485 standard to have the differential driver pins survive up to 250mA by clamping the current earlier. The device itself will clamp the currents as the PFET and NFET will saturate and limit current themselves before the 250mA occurs. Having a 10 ohm resistor isn't required but can help during high power transient events.

-Bobby