TXB0108: Data rate and drive current check

Roy Chou1

Genius 16210 points

Part Number: TXB0108
Other Parts Discussed in Thread: LSF0108, SN74LV4T125, SN74AXC8T245

Hi Team,

I would like to check if our TXB0108 could meet below requirement or not.

port A :1.8 V port B: 3.3V (current : 2mA)

port A frequency = 50MHz

If our solution could support, do we have any concern point like schematic components?

Regards,

Roy

over 5 years ago

0 Dylan Hubbard over 5 years ago

TI__Mastermind 46045 points

Hey Roy,

This device won't be able to handle that frequency with that supply configuration. All this information can be found in the data sheet as well.

0 Roy Chou1 over 5 years ago in reply to Dylan Hubbard

TI__Genius 16210 points

Hi Dylan,

I saw the table in datasheet showing as below. Does it mean we could transmit the signal which up to 60Mbps. And I have no idea about driving current spec. Could your let me know which page could I refer to?

Is LSF0108 more appropriate to TXB0108 in my condition?

Regards,

Roy

0 Clemens Ladisch over 5 years ago in reply to Roy Chou1

Guru 317370 points

TXB outputs can drive 0.02 mA.

A single cycle of a square wave has a high and a low pulse, so 50 MHz = 100 Mbps. However, if the signal is not a clock signal, then it is possible that the units got confused.

For unidirectional signals, you should use unidirectional (SN74LV4T125) or direction-controlled (SN74AXC8T245) translators.

0 Roy Chou1 over 5 years ago in reply to Clemens Ladisch

TI__Genius 16210 points

Hi Ladisch,

Where could I see the spec what you said "TXB outputs can drive 0.02 mA."

Thanks,

Roy

0 Clemens Ladisch over 5 years ago in reply to Roy Chou1

Guru 317370 points

In the test conditions for V_OL/V_OH.

0 Roy Chou1 over 5 years ago in reply to Clemens Ladisch

TI__Genius 16210 points

Hi Ladisch,

Thank you for your help. 20uA means portB output drive current, right?

And I have one question, if portA = 1.8V portB = 3.3V

if signal is from A to B. Do we have minimum drive current spec to drive our TXB0108?

Regards,

Roy

0 Clemens Ladisch over 5 years ago in reply to Roy Chou1

Guru 317370 points

The A and B I/Os are identical.

The minimum drive current is mentioned in section 8.3.2 of the datasheet. (At supply voltages lower than 5 V, the required drive current is proportionally lower.)

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TXB0108: Data rate and drive current check