DS32EL0421 DC Balance

user4766561

Other Parts Discussed in Thread: DS32EL0421, DS32EL0124

Hello,

According to the datasheet:

The DS32EL0421 has a built-in DC-balance encoder to support AC-coupled applications. When enabled, the input signal on TXIN4+/- is treated as a data valid bit. If TXIN4+/- is low, then the four bit nibbles from TXIN0-TXIN3 are taken to form a 16 bit word.

My question:

I need 8b10b decoding, so I must pull TXIN4 +/- down. However, it es necessary to pull down both data lines. Is it possible to pull only one of them down and DC Balance is working?

Thank you in advance!

over 9 years ago

0 Nasser Mohammadi over 9 years ago

TI__Guru* 93670 points

Greetings,

To operate DS32EL0124/0421 in a normal operating mode, TX4+/- should be pulled to a LVDS logic high to allow the transmitter - DS32EL0421 - to send SYNC signals once in a while. This allows the de-serializer to synchronize it's timing. Then to resume normal DC balanced data, TX4+/- should be pulled to LVDS logic low. Whether it is LVDS logic high or LVDS logic low, both polarity - TX4+ or TX4- - should be used. Else there could be an un-stable or random LVDS logic state. Please use both polarities.

Regards,,nasser

0 user4766561 over 9 years ago in reply to Nasser Mohammadi

Prodigy 170 points

Can i used for example GIPIO 0 to pulled TX4+/- high or low (programmable SMBus pull up and pull down resistor)?

0 Nasser Mohammadi over 9 years ago in reply to user4766561

TI__Guru* 93670 points

Greetings,

Please note GPIOs are LVCMOS while TX4+/- is LVDS. You can do this by using a LVCMOS to LVDS to convert LVCMOS GPIO to LVDS TX4+/-.

Regards,,nasser

0 user4766561 over 9 years ago in reply to Nasser Mohammadi

Prodigy 170 points

thank you

0 user4766561 over 9 years ago in reply to Nasser Mohammadi

Prodigy 170 points

Hello Nasser,

Do you mean both lines to pull down or "positive" line to low and "negative" line to high?
( for TX4+/-), because according to the datasheet: " If TXIN4+/- is low".

Thanks in advance!

0 Nasser Mohammadi over 9 years ago in reply to user4766561

TI__Guru* 93670 points

Greetings,

I meant LVDS logic low. As you noted we should pull positive line low and negative line high.

Regards,,nasser

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DS32EL0421 DC Balance