ISO1540: VOL of ISO1540

Ben Kuo

Part Number: ISO1540
Other Parts Discussed in Thread: ISO1640, TCA9800

Tool/software:

Hi Team,

We face to VOL issue in our application. Maximum VOL of ISO1540 is 0.8V which close to end point threshold and cause some issue.

Any suggest to get lower VOL?

We have try to use 3.3Vcc but cannot improve. And I found ISO1640 which have lower VOL which may be a possible solution in our application.

Regards,

Ben

1 month ago

0 Clemens Ladisch 1 month ago

Guru 284990 points

Both the ISO1540 and the ISO1640 have a voltage offset on their output in order to be able to differentiate signals coming from other devices. There is nothing you can do to change the behaviour of the ISO1x40 itself.

You can add a buffer with a different mechanism, e.g., TCA9800/1/2/3. (That one has other restrictions, i.e., no pull-up on the B side.)

0 Aaditya V. 1 month ago

TI__Genius 12035 points

Hi Ben,

Thanks for reaching out.

Clemens is correct here in regards to the ISO1540 characteristics and using a buffer an a possible solution. Please refer to this FAQ for more information regarding the VOL for ISO1540: [FAQ] Why is the logic LOW level output voltage, VOL1, up to 0.8V on Side1 of the ISO1540/ISO1541 and ISO1640/ISO1641 bidirectional I2C isolators? - Isolation forum - Isolation - TI E2E support forums

This E2E may also be helpful for you as well: ISO1540: Vol for ISO1540 - Isolation forum - Isolation - TI E2E support forums

Regards,
Aaditya Vittal