TCA9803: I2C Buffer/level shifter application

Roger Lin

Part Number: TCA9803
Other Parts Discussed in Thread: TCA4311A

Hi team,

I notice that we don't recommend adding any pull-up at the B-side of TCA9803 in other thread

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1602358/tca9517a-i2c-interface-lower-voltage-level-support-requirement

Since the customer has a trace to connect between main board & RF board, they required the buffer on both side, and wondernig if the pull-up on the TCA4311A side will affect the TCA9803's B-side or not

Thanks

Best regards,

Roger

25 days ago

0 Jack Guan 25 days ago

TI__Guru 59141 points

Hi Roger,

The team is out of office today due to US Holiday. Please expect a delay in response.

Regards,

Jack

0 Roger Lin 21 days ago in reply to Jack Guan

TI__Expert 4310 points

Hi Jack,

Update customer's schematic, please help with the review

The IOL sink current has a minimum 3mA at the 7330_SDA

Best regards,

Roger

0 Jack Guan 21 days ago in reply to Roger Lin

TI__Guru 59141 points

Hi Roger,

I need more time on this. Let me follow up tomorrow.

Regards,

Jack

0 Roger Lin 16 days ago in reply to Jack Guan

TI__Expert 4310 points

Hi Jack,

Any update so far?

best regards,

Roger

0 Jack Guan 15 days ago in reply to Roger Lin

TI__Guru 59141 points

Hi Roger,

Please ensure that pullups are used on the A-side of the device. If 7330_SDA is driving the B-side of the device, ensure that the output impedance (RILC) is <150ohms to sufficiently drive a low state through the B-side of the device.

Regards,

Jack

0 Roger Lin 14 days ago in reply to Jack Guan

TI__Expert 4310 points

Hi Jack,

Below is their slave's spec, it will have 180ohm at worst case(0.3*1.8V/3mA), could it cause any issues?

best regards,

Roger

+1 Jack Guan 14 days ago in reply to Roger Lin

TI__Guru 59141 points

Hi Roger,

The implementation is OK.

The worst case Rdson for their driver is 133ohms (0.4/ 3mA) , which is below the <150ohms max.

Regards,

Jack

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TCA9803: I2C Buffer/level shifter application