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Original question:

TLK1102E: TLK1102E

TLK1102E: Questions regarding electrical specifications and power supply of the equalizer

alexpioner
Prodigy 140 points
Part Number: TLK1102E

Hello.

I would also like to ask some questions regarding this equalizer:

1) Please take a look at the table "AC ELECTRICAL CHARACTERISTICS" at page 7 of TLK1102E datasheet. There are 2 parameters: "Vin, min", while its value is shown at MAX column (250mVp-p), and "Vin, max", which minimal value is stated (1600mVp-p). May you explain, which one is maximal value and which one is minimal one?

According to the diagrams at pages 20-23, it looks like the maximal equalizer input is 200mVp-p. So what should be the actual signal levels?

2) What is the recommended DC block capacitors value? We have placed 0.1uF capacitors, but according to their spec, the impedance @ 5GHz is about 7ohm (the resonant frequency of the capacitor is 25MHz). Is it acceptable?

3) I've checked the supply of the equalizer at our card. It has a ripple of about 50mVp-p at 4kHz. Is it acceptable?

Does this equalizer have some power supply recommendations? (supply filter capacitors, LDO, etc.)

Best regards

Alex

  • 0
    TI__Guru** 124050 points
    assign to the right person
  • 0 in reply to Brian Zhou
    Prodigy 140 points

    Hello, Brian

    How can I assign to the right person?

    I've assigned it to any expert.

  • 0 in reply to alexpioner
    Prodigy 140 points

    Hi, all

    Anybody can answer original questions?

  • 0
    TI__Mastermind 43795 points

    Hi Alex,

    1. The Vin range is 250 - 1600 mV launch amplitude.  The datasheet specifiies a worst case minumum of 250 mV.  So this ensures that the actual value of the part will be lower.  The opposite is true of the 1600 mV specification, the actual value will be higher. 

    The diagrams on pages 20-23 show the signal at the end of the transmission line.  With a k28.5 signal, even the lowest frequency components will experience significant losses over the media - that is why the amplitude is low.  At the Tx end of the line the amplitude is likely ~ 800mV

    2. We would recommend 0.1uF capacitors in 0402 or 0201 body size.  The X7R or X5R dielectrics are preferred. Larger capacitor body sizes can require more tuning to maintain a 100 Ohm transmission line impedance due to excess footprint capacitance.

    3. The ripple is okay.  I recommend a 0.1 and 1.0uF decoupling close to the device.  LDO is preferred for the additional noise rejection.

    Regards,

    Lee