DP83826E: DP83826E LED Configuration

Yang Wu

Part Number: DP83826E

Hi Team,

I have a question on the LED configuration for the basic mode. The DS says if strap selecting 0, a 1 kΩ pull-up resistor in series with the LED should be used and a 5 kΩ pull-down resistor. does there still need the 1.5KkΩ pull-down resistor to be parallel with the 5kΩ resistor?

In addition, since the the LED polarity will always be active low, does it means the LED will be always ON (because it's pulled up to 3.3V)? thanks a lot.

Best regards,

Yang

over 1 year ago

0 Gerome Cacho over 1 year ago

TI__Mastermind 33445 points

Hi Yang,

The 1.5k PD for the LED is required as this helps bias the voltage at strap sampling if intending to turn a default PU pin low.

For polarity, as this will be a low strap, this would be active high due to auto-polarity detection and correction.

Sincerely,

Gerome

0 Yang Wu over 1 year ago in reply to Gerome Cacho

TI__Expert 3080 points

Hi Gerome,

thanks for your reply. But I am confused here, the DS says basic mode doesn't have auto-polarity detection, right? if it doesn't have, I think the LED will be always ON. thanks.

Best regards,

Yang

0 Gerome Cacho over 1 year ago in reply to Yang Wu

TI__Mastermind 33445 points

Yang,

My apologies. Basic mode does not have polarity detection/correction and is active low. The datasheet has a typo, and the PD value should be 1.5k, not 5k. The LED should be connected to VCC for proper operation of active low LED polarity.

Sincerely,

Gerome

Interface

Interface forum

DP83826E: DP83826E LED Configuration