LSF0102-Q1: LSF0102-Q1

duan dan

Part Number: LSF0102-Q1
Other Parts Discussed in Thread: LSF0102, TXS0102

Hi, I want to use LSF0102 as a i2C level tranlator. When selecting VREFA voltage range is 1.0~3.7V, VREFB voltage is 5V, and A1 and A2 follow VREFA voltage(1.0~3.7V), I want to ask if B1 and B2 can pull up to any voltage between 0 and 5V, or is only between VCCA and 5V? (For example, if A1 voltage is 3.7V and B1 voltage is 2.5V, LSF0102 can work normally?)

1) 5.7 What pull up voltages are allowedon the A-sideand B-side? On eitherthe A-sideor B-side,resistorscan pull up to any voltage between Vref_A and 5 V. Therefore, it is possible to translate down to the B-side.

2)but there is different description in LSF0102 datashehet

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 243220 points

The I/Os on both sides can be pulled up to any voltage that is at least as high as Vref_A. At any voltage lower than Vref_A, the switch is closed and connects the corresponding A and B pins.

0 duan dan over 3 years ago in reply to Clemens Ladisch

Prodigy 30 points

Thanks for your replay. It is similiar with a PMOS FET, so At any voltage lower than Vref_A, the switch always turn off? The conclusion is that B side voltage must be higher than VREFA, right?

0 duan dan over 3 years ago in reply to Clemens Ladisch

Prodigy 30 points

Thanks for your replay. It is similiar with a PMOS FET, so At any voltage lower than Vref_A, the switch always turn off? The conclusion is that B side voltage must be higher than VREFA, right?

0 duan dan over 3 years ago

Prodigy 30 points

another question: whether I can use LSF0102 and TXS 0102 to cascade

0 Dylan Hubbard over 3 years ago in reply to duan dan

TI__Mastermind 42600 points

Hey Duan,

Correct, the B side would need to be above Vref-A. Can you clarify exactly what you mean by cascade?

0 duan dan over 3 years ago in reply to Dylan Hubbard

Prodigy 30 points

Thanks for your replay. What I mean is that using TXS0102 and LSF0102 as I2C chian: 2.5V to 5V (use TXS0102 as translator), then 5V to 1~3.7V(use LSF0102 as translator). Is it ok?

+1 Dylan Hubbard over 3 years ago in reply to duan dan

TI__Mastermind 42600 points

Hey Duan,

This may be possible depending on the drive strength of the controller device and peripheral device. There would be added low side offset for each translator do to current going through the pass FET rdson. I would recommend grabbing EVMs from the product folders and running some tests to make sure the high offset doesn't cause issues.

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LSF0102-Q1: LSF0102-Q1