CLC034MAX/NOPB National Semiconductor, CLC034MAX/NOPB Datasheet - Page 5

• Manufacturer Part Number: CLC034MAX/NOPB
• Manufacturer: National Semiconductor

Specifications of CLC034MAX/NOPB

• Lead Free Status / Rohs Status: Compliant

Block Diagram
Device Operation
BLOCK DESCRIPTION
The Equalizer Filter block is a multi-stage adaptive filter. If
Bypass is high, the equalizer filter is disabled.
The DC Restoration / Level Control block receives the
differential signals from the equalizer filter block. This block
incorporates a self-biasing DC restoration circuit to fully DC
restore the signals. If Bypass is high, this function is dis-
abled.
The signals before and after the DC Restoration / Level
Control block are used to generate the Automatic Equal-
ization Control (AEC) signal. This control signal sets the
gain and bandwidth of the equalizer filter. The loop response
in the AEC block is controlled by an external 1µF capacitor
placed across the AEC+ and AEC- pins. Cable Length
Indicator (CLI) is derived from this block.
The Carrier Detect / Mute block generates the carrier detect
signal and controls the mute function of the output. This
block utilizes the bi-directional CD/MUTE signal along with
Mute Reference (MUTE
The Output Driver produces SDO and SDO.
CABLE LENGTH INDICATOR (CLI)
The cable length indicator provides a voltage to indicate the
length of cable being equalized. The CLI voltage decreases
as the cable length increases.
MUTE REFERENCE (MUTE
The mute reference determines the amount of cable to
equalize before automatically muting the outputs. This is set
by applying a voltage inversely proportional to the length of
REF
).
REF
)
5
cable to equalize. As the applied MUTE
creased, the amount of cable that can be equalized before
carrier detect is de-asserted and the outputs are muted is
decreased. MUTE
equalization before muting.
CARRIER DETECT / MUTE (CD/MUTE)
Carrier Detect / Mute is bi-directional, serving as both a
carrier detect (output function) and mute (input function).
When used as an output, CD/MUTE determines if a valid
signal is present at the CLC034 input. If MUTE
the carrier detect threshold will be altered accordingly.
CD/MUTE provides a high voltage when no signal is present
at the CLC034 input, and the outputs are automatically
muted. This is true if no cable is connected to the input or if
the input cable is very long, typically 450m Belden 1694A for
1.485 Gbps input or 550m Belden 1694A for 270 Mbps input
(with standard 800 mV
is low when a valid input signal has been detected, and the
outputs are automatically enabled.
As an input, CD/MUTE can be used to override the carrier
detect and manually mute or enable the CLC034 outputs.
Applying a high input to CD/MUTE will mute the CLC034
outputs. Applying a low input will force the outputs to be
active regardless of the length of cable or the state of
MUTE
INPUT INTERFACING
The CLC034 accepts either differential or single-ended in-
put. The input must be AC coupled. Transformer coupling is
not supported.
REF
.
REF
may be left unconnected for maximum
P-P
color bar input signals). CD/MUTE
REF
voltage is in-
REF
www.national.com
20085902
is used,