Datasheet

AEC+
Equalizer
Filter
AEC-
MUTE
MUTE
REF
DC
Restoration/
Level Control
Automatic
Equalization
Control
SDI
SDI
SDO
SDO
BYPASS
Output
Driver
6
MUTE
REF
Energy
Detect
Energy
Detect
CD
AUTO SLEEP
Carrier
Detect
SPI_EN
SPI Control
LMH0384
SNLS308F –APRIL 2009–REVISED APRIL 2013 www.ti.com
BLOCK DIAGRAM (PIN MODE)
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 disabled.
The signals before and after the DC Restoration / Level Control block are used to generate the Automatic
Equalization 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.
The Carrier Detect block generates the carrier detect signal based on the SDI input and an adjustment from the
Mute Reference block.
The SPI Control block uses the MOSI, MISO, SCK, and SS signals in SPI mode to control the SPI registers.
SPI_EN selects between SPI mode and pin mode. In pin mode, SPI_EN is driven logic low.
The Output Driver produces SDO and SDO.
MUTE REFERENCE (MUTE
REF
)
The mute reference sets the threshold for CD and (with CD tied to MUTE) 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 cable to equalize. The applied voltage must be greater than the MUTE
REF
floating voltage (typically
1.3V) in order to change the CD threshold. As the applied MUTE
REF
voltage is increased, the amount of cable
that can be equalized before carrier detect is de-asserted and the outputs are muted is decreased. MUTE
REF
may be left unconnected or connected to ground for normal CD operation.
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