LMH0394SQ/NOPB National Semiconductor, LMH0394SQ/NOPB Datasheet - Page 9

• Manufacturer Part Number: LMH0394SQ/NOPB
• Description: IC EQUALIZER CABLE 16-LLP
• Manufacturer: National Semiconductor

Specifications of LMH0394SQ/NOPB

• Applications: Amplifier
• Interface: SPI Serial
• Voltage - Supply: 2.5V
• Package / Case: *
• Mounting Type: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CARRIER DETECT (CD) AND MUTE
Carrier detect CD indicates if a valid signal is present at the
LMH0394 input. This signal is logical OR operation of the in-
ternal energy detector and MUTE
internal energy detector detects energy across different data
rates. If MUTE
altered accordingly. CD provides a high voltage when no sig-
nal is present at the LMH0394 input. CD is low when a valid
input signal is detected.
MUTE can be used to manually mute or enable SDO and
SDO. Applying a high input to MUTE will mute the LMH0394
outputs by forcing the output to a logic 1. Applying a low input
will force the outputs to be active.
In pin mode, CD and MUTE may be tied together to automat-
ically mute the output when no input signal is present.
AUTO SLEEP
The auto sleep mode allows the LMH0394 to power down
when no input signal is detected. If the AUTO SLEEP pin is
set high, the LMH0394 goes into a deep power save mode
when no signal is detected. The device powers on again once
an input signal is detected. The auto sleep functionality can
be turned off by setting AUTO SLEEP low or tying this pin to
ground. An additional auto sleep setting available in SPI mode
can be used to force the equalizer to power down regardless
of whether there is an input signal or not. Auto sleep has
precedence over mute and bypass modes.
In auto sleep mode, the time to power down the equalizer
when the input signal is removed is less than 200 µs and
should not have any impact on the system timing require-
ments. The device will wake up automatically once an input
signal is detected, and the delay between signal detection and
full functionality of the equalizer is negligible (about 5 ms). The
overall system will be limited only by the settling time constant
of the equalizer adaptation loop.
INPUT INTERFACING
The LMH0394 accepts either differential or single-ended in-
put. The input must be AC coupled. The
(Pin Mode)
figuration for a single-ended input. The unused input must be
properly terminated as shown.
The LMH0394 can be optimized for different launch ampli-
tudes via the SPI (see
TION
The LMH0394 correctly handles equalizer pathological sig-
nals for standard definition and high definition serial digital
video, as described in SMPTE RP 178 and RP 198, respec-
tively.
OUTPUT INTERFACING
SDO and SDO together are internally terminated 100Ω LVDS
outputs. These outputs can be DC coupled to most common
differential receivers.
in the
diagram on the front page shows the typical con-
SPI Register Access
REF
is used, the carrier detect threshold will be
LAUNCH AMPLITUDE OPTIMIZA-
section).
REF
setting (if used). The
Typical Application
9
The default output common mode voltage (V
output common mode voltage may be adjusted via the SPI in
200 mV increments, from 0.8V to 1.2V (see
ER ADJUSTMENTS AND DE-EMPHASIS SETTING
SPI Register Access
mode is supply referenced, the common mode voltage is
about 1.35V (for 700 mV
output common mode voltage offers flexibility for interfacing
to many types of receivers.
The default differential output swing (V
The differential output swing may be adjusted via the SPI.
Valid options are 400, 600, 700, or 800 mV
DRIVER ADJUSTMENTS AND DE-EMPHASIS SETTING
the
The LMH0394 output should be DC coupled to the input of
the receiving device as long as the common mode ranges of
both devices are compatible. 100Ω differential transmission
lines should be used to connect between the LMH0394 out-
puts and the input of the receiving device where possible.
Figure 5
tween the LMH0394 and LMH0346 SDI reclocker. All that is
required is the 100Ω differential termination as shown. The
resistor should be placed as close as possible to the
LMH0346 input. If desired, this network may be terminated
with two 50Ω resistors and a center tap capacitor to ground
in place of the signal 100Ω resistor.
Figure 6
tween the LMH0394 and LMH0356 SDI reclocker. The
LMH0356 inputs have 50Ω internal terminations (100Ω dif-
ferential) to terminate the transmission line, so no additional
components are required.
The LMH0394 may be AC coupled to the receiving device
when necessary. For example, the LMH0394 outputs are not
strictly compatible with 2.5V CML and thus should not be
connected via 50Ω resistors to 2.5V. If the input common
mode range of the receiving device is not compatible with the
output common mode range of the LMH0394, then AC cou-
pling is required. Following the AC coupling capacitors, the
signal may have to be biased at the input of the receiving de-
vice.
The LMH0394 output driver is equipped with programmable
output de-emphasis to minimize inter-symbol interference
caused by the loss dispersion from driving signals across
PCB traces (see
DE-EMPHASIS SETTING
tion). De-emphasis works with all combinations of output
common mode voltage and output voltage swing settings to
support DC coupling to the receiving device.
SPI Register Access
shows an example of a DC-coupled interface be-
shows an example of a DC-coupled interface be-
OUTPUT DRIVER ADJUSTMENTS AND
section). When the output common
P-P
section).
differential swing). This adjustable
in the
SPI Register Access
SSP-P
P-P
OUTPUT DRIV-
OS
) is 700 mV
(see
) is 1.2V. The
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OUTPUT
in the
sec-
P-P
in
.