TCA9517: About datasheet interpretation VIL and VILC, System VS TCA9517 condition

Katsumi Takada

Part Number: TCA9517

Hi, team.Please follow datasheet interpretation.

Q1: If system device use VOL=0.4V,
which of the datasheet TCA9517 side should

Look at:(Vccb=3.3)

VIL(=0.3*Vccb=0.99V(max))
or
VILC(=0.4V(typ))

Q2:I think VIL would be fine, but in what kind of situation should VILC be used.

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 322000 points

The specified V_IL value for SDAB/SCLB is explained in footnote (2), but it is meaningless for you. You need to use the lower value, which is always V_ILC.

0 Tyler Townsend over 2 years ago

TI__Guru 59208 points

Hi Katsumi,

Clemens is correct about the footnote. VIL for the B-side is the specification for the first low level seen by the SDAB and SCLB lines. VILC is for the second subsequent low levels seen by the SDAB and SCLB lines.

All devices connected on the B-side of the I2C bus should be able to drive an output low voltage level below the typical VILC spec (0.4V). VOLB = <0.4V for all devices. This spec must be adhered to so that the device can properly determine which side is driving a low-voltage signal in order to not lock the I2C bus.

TI specs the VIL = 30% of VCCB because this is the spec listed in the I2C standard. For this particular buffer, an additional requirement of VILC is needed for proper operation of the device.

Regards,

Tyler

0 Katsumi Takada over 2 years ago in reply to Clemens Ladisch

Prodigy 50 points

Clemens-san, Thank you for oppinion.
I must the VILC lower value.
Thank you so much
Best Regards,
katsumi

0 Katsumi Takada over 2 years ago in reply to Tyler Townsend

Prodigy 50 points

Tyler-san, Thank you for answer.
B port of I2C bus is less than VILC0.4.
All VOLB=<0.4V,
and
VIL = VCCB = 30% I was able to understand that it is based on the I2C standard.

Thank you for the deteiled explanation.

Best Regards,
katsumi

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TCA9517: About datasheet interpretation VIL and VILC, System VS TCA9517 condition