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ADCMP551 output cannot be terminated to a proper level to other device

Question asked by carnby on Mar 27, 2015
Latest reply on Mar 29, 2015 by msamera

Hello,

I use ADCMP551 with 5V VCCI, and connect the LVPECL output to other differential receiver. As we knows, LVPECL almost use 3.3V power supply and terminate the output to 3.3V-2V=1.3V level. And other LVPECL receiver was designed to assume the transmitter's power supply was 3.3V or 2.5V.

灏廞鎴浘-20150327210106.png

In the ADCMP551 datasheet (Rev. B, page4), it says VCCO-VCCI should be larger than -0.2V and less than 2.3V. As my ADCMP551 uses 5V VCCI, the VCCO should locate between 4.8V and 7.3V. According to the datasheet, I should terminate the LVPECL output to VCCO-2V.

 

So the problem is I cannot give the LVPECL output a proper terminated voltage to connect to other receiver.

Do I misunderstand the datasheet or there is other solution?

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