EQCO850SC.3-HS Datasheet, PDF (5/24 Pages) Microchip Technology – Pb-Free and RoHS Compliant

EQCO850SC.3-HS/EQCO875SC.3-HS
FIGURE 1-3:
SDIp
SDIn
EQCO850SC-HS BLOCK DIAGRAM SHOWING ELECTRICAL CONNECTIONS
EQCO850SC
Input
Pre-Driver
Active Signal
Splitter/Combiner
SDIO
REF
Transmit
Wake-Up
Detection
Equalizer
Core
SDOp
SDOn
RX Output
Driver
1.1 SDIp/SDIn
SDIp/SDIn together form a differential input pair. The
serial data received on these pins will be transmitted on
SDIO. The Input Pre-Driver automatically corrects for
variations in signal levels and different edge slew rates
at these inputs before they go into the Active Splitter/
Combiner for transmission over the coax.
SDIp and SDIn inputs are differentially terminated by
100Ω on-chip. The center of the 100Ω is connected to
DGND with a 10 kΩ resistor for DC biasing. The inputs
also have protection diodes to ground for ESD
purposes. Always AC-couple these inputs to the
outputs of the LVDS driver.
A Transmit Wake-Up detection circuit puts both the
Input Pre-Driver and the Active Signal Splitter/
Combiner into a low-power mode when no signal is
detected on the SDIp/SDIn signal pair (except in Mode
B, where transmit circuit is permanently on).
1.2 SDIO/REF
The signal on the SDIO pin is the sum of the incoming
signal (i.e. the signal transmitted by the EQCO850SC-HS
on the far-end side of the coax) and the outgoing signal
(i.e. the signal based on SDIp/SDIn). The far-end signal is
extracted by subtraction of the near-end signal, and it is
this voltage that the equalizer analyzes and adaptively
equalizes for level and frequency response based on the
knowledge that the originating signal is DC-balanced and
run-length encoded before transmission.
The REF signal carries a precise anti-phase current to
the transmit current on SDIO. REF must be connected
directly to AGND at the connector (see Figure 3-1) via a
resistor precisely matched to the impedance of the
coaxial cable used.
 2010-2015 Microchip Technology Inc.
1.3 SDOp/SDOn
SDOp/SDOn together form a differential pair outputting
the reconstructed far-end transmit signal. The
EQCO850SC-HS uses LVDS drivers with source
matching for a 100Ω transmission line. This LVDS
signal can normally be connected (subject to input
common-mode requirements) directly to the RX signal
pair of a standard LVDS receiver.
1.4 CLK, SI
These pins are used for production test and/or reserved
for future options. For normal operation, connect them to
DGND as indicated in Table 1-1.
DS60001313A-page 5