TLK110: RX+- TX+- Amplitude is too low for Ethernet Test

Zhou Fang67

Expert 4250 points

Part Number: TLK110

Hi Expert,

We meet an problem for Ethernet test for RX+- and TX+- differential amplitude test.

The standard require:

The differential amplitude from receiver side should be 1.9V<RX+-<2.1V, which is the standard PMD amplitude.

However, from customer board which use TLK110, the differential amplitude is around 1.6V.

The schematic is just look like the EVM, and Auto-negotiation with 10/100M half/full duplex mode is used.

Is there any error can lead to low differential amplitude?

Thanks

Zhou

over 7 years ago

0 Rob Rodrigues over 7 years ago

TI__Mastermind 19780 points

Hi Zhou,

Can you measure the voltage at the RBIAS pin of the TLK110 device?

Best Regards,

0 Zhou Fang67 over 7 years ago in reply to Rob Rodrigues

TI__Expert 4250 points

Hi Rob,

Thanks for reply.

Voltage on RBIAS pin is 1.56V~1.60V with oscilloscope with "Mean".
The differential impedance 100Ohm for MDI is not followed or carefully calculated. Does this contribute for lower amplitude?

Thanks.
Zhou

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TLK110: RX+- TX+- Amplitude is too low for Ethernet Test