DS25BR440: Output state when no input?

Gregory Duperon

Expert 7530 points

Part Number: DS25BR440
Other Parts Discussed in Thread: DS25BR400

What is the state of the outputs when there is a loss of signal at the input?

Do they go into a known state?

I see that the /LOS are asserted. But, what about output pins?

over 5 years ago

0 Lee Sledjeski over 5 years ago

TI__Mastermind 43795 points

Hi Gregory,

The outputs will still be active.

The LOSn# and PWDNn# pins could be connected together to disable the outputs when the input signal is removed.

Regards,

Lee

0 Gregory Duperon over 5 years ago in reply to Lee Sledjeski

TI__Expert 7530 points

I have another related question. DS25BR400 states in the datasheet that a DC bias should not be applied to the part input. Because I have a modular system where I need to account for one or multiple channels not being connected, I need to make sure the input is held in a known state so I don’t end up with floating inputs and worse toggling output IO.

Given the comment about DC bias, is it not possible for me to put pull ups and pull downs on the input P/N pairs to ensure a stable input state? I would plan for holding the voltage at around VID = 200 mV to be near but above the minimum with margin.

0 Gregory Duperon over 5 years ago in reply to Gregory Duperon

TI__Expert 7530 points

Hi Lee,

Any feedback on this? Thanks.

0 Lee Sledjeski over 5 years ago in reply to Gregory Duperon

TI__Mastermind 43795 points

Hi Gregory,

The DS25BR400 is not compatible with signals down to DC. The inputs are capacitively coupled internally so the external voltage bias will not translate to the device and produce a stable output state.

Regards,

Lee

Interface

Interface forum

DS25BR440: Output state when no input?