EQCO62R20.3 Datasheet, PDF (15/34 Pages) Microchip Technology – EQCO62R20.3 6.25 Gbps Asymmetric Coax Equalizer

EQCO62R20.3/EQCO31R20.3
2.2 Guidelines for Power Transmit Unit
At the Power-IN connection, a voltage supply is
expected for powering a device (e.g. a camera) at the
other end of the cable.
This voltage supply should have low ripple. High-
frequency ripple will be rejected by C8/L1/FB1/FB2
filtering in the reference circuit. However, mid-frequency
ripple is to be avoided by the power supply itself.
In a typical application, one could want to step-up from
a 12V supply (e.g. in a PC) to a 24V power supply for
CoaXPress. It is in this case preferred to use a DC-to-
DC converter that has a high switching frequency (e.g.
2 MHz) above one that has lower switching frequency
(200 kHz). The latter typically induces larger voltage
spikes at the Power-IN connection. These will be only
partially filtered out by said filter; the remainder will
become crosstalk for the uplink channel.
When too much crosstalk remains on the uplink
channel, additional power-supply filtering is required.
This may be achieved by placing an extra filter network
(not shown) in series with the Power-IN node.
2.3 Power Over CoaXPress
The EQCO62R20.3 is compatible with the Power over
CoaXPress system (PoCXP) using the circuit from
Figure 2-2. Hence, power can be switched on and off by
the host (e.g. frame grabber) through the 10 µH inductor
specified by the CXP standard. This switching is
supported through a relay and through an electronic
switch.
Powering through a wide-band bias-T is also supported.
The EQCO62R20.3 is also protected against the
following events:
• Hot plugging by frame grabber: in case the frame
grabber has already applied its 24V on the coax
when connecting the cable, no damage will occur
to the EQCO62R20.3 when connecting the
powered coax cable.
• Fast turn-on and turn-off of power supply by
frame grabber.
 2012-2016 Microchip Technology Inc.
DS60001302B-page 15