TCA9800: your recommended I2C buffer IC for week input driving current

Yusuke Mukuno

Expert 7395 points

Part Number: TCA9800
Other Parts Discussed in Thread: TCA9511A

Hi expert

Could you please let me know your recommended I2C buffer device for the following condition?

We proposed TCA9800/1/2/3. however, input resistance spec <150ohm.

The drive current in the Host device is weak. IOL=0.63mA, VOL=0.36V, 571ohm.

The drive current in the slave device is also weak. IOL=1.0mA, VOL=0.36V, 360ohm.

Thanks

Muk

over 5 years ago

0 BOBBY over 5 years ago

TI__Guru 73591 points

What Vcc levels and I2C operating speed are you trying to support?

"The drive current in the Host device is weak. IOL=0.63mA, VOL=0.36V, 571ohm.

The drive current in the slave device is also weak. IOL=1.0mA, VOL=0.36V, 360ohm."

This seems to indicate that the master/slaves are not I2C compliant. What are the max ViL levels for the master and slave?

Thanks,

-Bobby

0 Yusuke Mukuno over 5 years ago in reply to BOBBY

TI__Expert 7395 points

Hi Bobby-san,

VccA=1.8, VccB=1.8 (If we need VccA<VccB, Vcc can be changed 1.9V. but, customer want to use 1.8V as possible.)

I2C Fast mode : 400 kHz

Master ViL= 0.35 x VDD

Slave ViL=0.3 x VDD

Customer understand that the master/slaves are not I2C compliant....

Please let me know if you have any solution /idea.

Thanks

Muk

0 Yusuke Mukuno over 5 years ago in reply to Yusuke Mukuno

TI__Expert 7395 points

Hi Bobby-san,

Could you please give me your comment?

Thanks

Muk

0 BOBBY over 5 years ago in reply to Yusuke Mukuno

TI__Guru 73591 points

Hey Muk,

I can't think of a device in our portfolio which would be able to redrive the signal at 1.8V. The closest device I could think of is TCA9511A but its low level Vcc is 2.3V not 1.8V. Our TCA980x is the only family we have that would meet the Vcc requirements but since the master/slave do not meet the Rdson requirement, unfortunately I don't see a possible solution at the time.

-Bobby

0 Yusuke Mukuno over 5 years ago in reply to BOBBY

TI__Expert 7395 points

Hi Bobby-san,

Thank you for your answer!

Muk

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TCA9800: your recommended I2C buffer IC for week input driving current