DS10BR150: Unused pin and output voltage with external termination resister

Michiaki Tanii

Expert 4470 points

Part Number: DS10BR150
Other Parts Discussed in Thread: DS25BR110, DS25BR120, , DS25BR100, DS25BR150

Our customer is considering the one of the below and therefore would like to use same layout.

DS25BR110

DS25BR120

DS10BR150

DS25BR100

DS25BR150

1pin and 4pin of DS10BR150 / DS25BR150 are NC.

Are there any issues if these pins were connected to GND or VCC ?

All the above 5 products could output 350 mV with external 100 ohm termination resister ?

Our customer assume it would be OK because the datasheet describe differential output voltage is 350 mV with test condition RL = 100 ohm.

Thank you and best regards,

Michiaki

over 4 years ago

0 Lee Sledjeski over 4 years ago

TI__Mastermind 43795 points

Hi Michiaki,

There is no issue connecting the NC pins to GND or VCC.

With a RLoad = 100 Ohms the peak to peak voltage measured across the load will be 700mV. Each pin (OUTP and OUTN) individually has a 350mV output swing. Since they are differential the swings are 180 degrees out of phase. The resulting waveform OUTP - OUTN will be a 700mV waveform if measured by an oscilloscope.

Regards,

Lee

0 Michiaki Tanii over 4 years ago in reply to Lee Sledjeski

TI__Expert 4470 points

Please let me make sure why differential voltage is 700mV.

Customer thinks that the differential voltage would be 175mV due to be connected internal 100 ohm with external 100 ohm with parallels.(=3.5mA * 100 ohm // 100 ohm).

I would much appreciate you double check why it is 2*350mV.

Thank you and best regards,

Michiaki

0 Lee Sledjeski over 4 years ago in reply to Michiaki Tanii

TI__Mastermind 43795 points

Hi Michiaki,

The attached graphic shows the output amplitudes of the DS25BRxxx devices.

Regards,

Lee

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DS10BR150: Unused pin and output voltage with external termination resister