ISO1640: low level issue

Tommy Tzeng

Part Number: ISO1640

Hi Sir,

we adding ISO1640 to SMBUS solution, we measure side1 as follows, please look at the red section, the low level will not reach 0 , would you like to ask if you know what cause it?

the same status for pull-up resistor 1k and 4.7k ohm.

over 5 years ago

0 Koteshwar Rao over 5 years ago

TI__Guru 57445 points

Hi Tommy,

Thanks for reaching out.

What you have seen in the waveform is the expected behavior. This is done by design to distinguish between two different LOWs to achieve bidirectional operation. Please see below FAQ for more details. For most customers, this shouldn't cause any problems in the system. Let me know if it is otherwise for your customer, thanks.

https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/757564/faq-why-is-the-logic-low-level-output-voltage-vol1-up-to-0-8v-on-side1-of-the-iso1540-and-iso1541-bidirectional-i2c-isolators

Regards,
Koteshwar Rao

Isolation

Isolation forum

ISO1640: low level issue