EQCO850SC.3-HS Datasheet, PDF (6/24 Pages) Microchip Technology – Pb-Free and RoHS Compliant

EQCO850SC.3-HS/EQCO875SC.3-HS
2.0 CIRCUIT OPERATION
2.1 Pre-Driver
The pre-driver removes any dependency on the LVDS
transmitter for the amplitude and rise time of the outgo-
ing signal on SDIO.
2.2 Active Signal Splitter/Combiner
The active splitter/combiner controls the amplitude and
rise time of the outgoing coax signal and transmits it via
a precise 50Ω output termination resistor. The output
resistor when balanced with the coax characteristic
impedance also forms part of a hybrid splitter circuit
which subtracts the TX output from the signal on the
SDIO output to give yield the far end TX signal. The
return loss of the coax termination is a key factor in the
performance of the line hybrid.
2.3 Equalizer Core
The EQCO4850SC-HS has an embedded high-speed
equalizer in the receive path with unique characteristics:
• Auto-adaptive
The equalizer controls a multiple-pole analog filter
which compensates for attenuation of the cable, as
illustrated in Figure 2-1. The filter frequency response
needed to restore the signal is automatically determined
by the device using a time-continuous feedback loop
that measures the frequency components in the signal.
Upon the detection of a valid signal, the control loop
converges within a few microseconds.
• Variable gain
EQCO850SC-HSs are used in pairs; one at each end of
the coax. The EQCO850SC-HS can be used with any
LVDS driver with a differential transmit amplitude in the
range of 300 mV to 800 mV; the transmit amplitude on the
coax is regulated by the input pre-driver. The receiver
equalizer has variable gain to compensate for attenuation
through the coax. Example equalizer performance
measurements can be found in Appendix B:Typical
Operating Characteristics.
FIGURE 2-1:
PRINCIPLE OF EQUALIZER OPERATION
DS60001313A-page 6
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