NSC LMH0344SQ

April 2007
LMH0344
3Gbps HD/SD SDI Adaptive Cable Equalizer
General Description
Features
The LMH0344 3Gbps HD/SD SDI Adaptive Cable Equalizer
is designed to equalize data transmitted over cable (or any
media with similar dispersive loss characteristics). The equalizer operates over a wide range of data rates from 143 Mbps
to 2.97 Gbps and supports SMPTE 424M, SMPTE 292M,
SMPTE 344M, and SMPTE 259M.
The LMH0344 implements DC restoration to correctly handle
pathological data conditions. The equalizer may be driven in
either a single ended or differential configuration.
Additional features include separate carrier detect and output
mute pins which may be tied together to mute the output when
no signal is present. A programmable mute reference is provided to mute the output at a selectable level of signal degradation.
■ SMPTE 424M, SMPTE 292M, SMPTE 344M, and SMPTE
259M compliant
■ Supports DVB-ASI at 270 Mbps
■ High data rates: 143 Mbps to 2.97 Gbps
■ Equalizes up to 120 meters of Belden 1694A at 2.97 Gbps,
up to 140 meters of Belden 1694A at 1.485 Gbps, or up to
350 meters of Belden 1694A at 270 Mbps
■ Equalizes 0-100m of Belden 1694A at 2.97 Gbps with
0.3 UI maximum output jitter
■ Manual bypass and output mute with a programmable
threshold
■ Single-ended or differential input
■
■
■
■
■
50Ω differential outputs
Single 3.3V supply operation
280mW typical power consumption with 3.3V supply
Footprint compatible with the LMH0044
Replaces the Gennum GS2974 or GS2974A
Applications
■ SMPTE 424M, SMPTE 292M, SMPTE 344M, and SMPTE
259M serial digital interfaces
■ Serial digital data equalization and reception
■ Data recovery equalization
Typical Application
20199001
© 2007 National Semiconductor Corporation
201990
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LMH0344 3Gbps HD/SD SDI Adaptive Cable Equalizer
PRELIMINARY
LMH0344
Absolute Maximum Ratings (Note 1)
Supply Voltage
Input Voltage (all inputs)
Storage Temperature Range
Junction Temperature
Lead Temperature
(Soldering 4 Sec)
Package Thermal Resistance
θJA 16-pin LLP
θJC 16-pin LLP
ESD Rating (HBM)
ESD Rating (MM)
Recommended Operating
Conditions
−0.5V to 3.6V
−0.3V to VCC+0.3V
−65°C to +150°C
+150°C
Supply Voltage (VCC – VEE)
Input Coupling Capacitance
AEC Capacitor (Connected between
AEC+ and AEC-)
Operating Free Air Temperature (TA)
+260°C
3.3V ±5%
1.0 µF
1.0 µF
0°C to +85°C
+43°C/W
+8°C/W
8kV
250V
DC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Notes 2, 3).
Symbol Parameter
VCMIN
Input Common Mode Voltage
VSDI
Input Voltage Swing
VCMOUT
Output Common Mode Voltage
VSDO
Output Voltage Swing
Conditions
Reference
Min
SDI, SDI
At LMH0344 input, (Notes 4, 5)
720
50Ω load, differential
MUTEREF
MUTEREF Range
CD Output Voltage
Carrier not present
CD
2.4
MUTE
2.0
800
Supply Current
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950
750
mVP-P
1.3
V
0.7
V
V
V
V
0.8
85
2
mVP−P
V
Max to force outputs active
ICC
V
0.4
Min to mute outputs
Units
VCC –
VSDO/2
Carrier present
MUTE Input Voltage
Max
1.9
SDO, SDO
MUTEREF DC Voltage (floating)
Typ
V
mA
LMH0344
AC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Note 3).
Symbol Parameter
BRSDI
Conditions
Max
Units
2970
Mbps
270 Mbps, Belden 1694A,
0-350 meters (Note 4)
0.2
UI
1.485 Gbps, Belden 1694A,
0-140 meters (Note 4)
0.25
UI
2.97 Gbps, Belden 1694A,
0-100 meters (Note 4)
0.3
UI
Input Data Rate
Jitter for various Cable Lengths
(with equalizer pathological)
Reference
Min
SDI, SDI
143
2.97 Gbps, Belden 1694A,
100-120 meters
tr,tf
Typ
0.4
SDO, SDO
UI
Output Rise Time, Fall Time
20% – 80%, (Note 4)
90
130
ps
Mismatch in Rise/Fall Time
(Note 4)
2
15
ps
tOS
Output Overshoot
(Note 4)
1
5
%
ROUT
Output Resistance
single-ended
RLIN
Input Return Loss
5 MHz - 1.5 GHz, (Note 6)
RIN
Input Resistance
single-ended
1.3
kΩ
CIN
Input Capacitance
single-ended
1
pF
Ω
50
1.5 GHz - 3.0 GHz, (Note 6)
SDI, SDI
15
dB
10
dB
Note 1: "Absolute Maximum Ratings" are those parameter values beyond which the life and operation of the device cannot be guaranteed. The stating herein of
these maximums shall not be construed to imply that the device can or should be operated at or beyond these values. The table of "Electrical Characteristics"
specifies acceptable device operating conditions.
Note 2: Current flow into device pins is defined as positive. Current flow out of device pins is defined as negative. All voltages are stated referenced to
VEE = 0 Volts.
Note 3: Typical values are stated for VCC = +3.3V and TA = +25°C.
Note 4: Specification is guaranteed by characterization.
Note 5: The maximum input voltage swing assumes a nonstressing, DC-balanced signal; specifically, the SMPTE-recommended color bar test signal. Pathological
or other stressing signals may not be used. This specification is for 0m cable only.
Note 6: Input return loss is dependent on board design. The LMH0344 meets this specification on the SD344 evaluation board.
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LMH0344
Connection Diagram
20199003
The exposed die attach pad is a negative electrical terminal for this device. It should be connected to the negative power supply voltage.
16-Pin LLP
Order Number LMH0344SQ
See NS Package Number SQB16A
Pin Descriptions
Pin #
Name
Description
1
VEE
Negative power supply (ground).
2
SDI
Serial data true input.
3
SDI
Serial data complement input.
4
VEE
Negative power supply (ground).
5
AEC+
AEC loop filter external capacitor (1µF) positive connection.
6
AEC-
AEC loop filter external capacitor (1µF) negative connection.
7
BYPASS
Bypasses equalization and DC restoration when high. No equalization occurs in this mode.
8
MUTEREF
Mute reference. Sets the threshold for CD and (with CD tied to MUTE) determines the maximum
cable to be equalized before muting. MUTEREF may be unconnected for maximum equalization.
9
VEE
Negative power supply (ground).
10
SDO
Serial data complement output.
11
SDO
Serial data true output.
12
VEE
Negative power supply (ground).
13
VCC
Positive power supply (+3.3V).
14
MUTE
Output mute. To disable the mute function and enable the output, MUTE must be tied to GND or
a low level signal. To force the outputs to a muted state, tie to VCC. CD may be tied to this pin to
inhibit the output when no input signal is present. MUTE has no function in BYPASS mode.
15
CD
Carrier detect. CD is high when no signal is present. CD has no function in BYPASS mode.
16
VCC
Positive power supply (+3.3V).
DAP
VEE
Connect exposed DAP to negative power supply (ground).
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LMH0344
Block Diagram
20199002
CARRIER DETECT (CD) AND MUTE
Carrier detect CD indicates if a valid signal is present at the
LMH0344 input. If MUTEREF is used, the carrier detect threshold will be altered accordingly. CD provides a high voltage
when no signal is present at the LMH0344 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 LMH0344
outputs. Applying a low input will force the outputs to be active.
CD and MUTE may be tied together to automatically mute the
output when no input signal is present.
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 / Mute block generates the carrier detect
signal and controls the mute function of the output. This block
utilizes the CD and MUTE signals along with Mute Reference
(MUTEREF).
The Output Driver produces SDO and SDO.
INPUT INTERFACING
The LMH0344 accepts either differential or single-ended input. The input must be AC coupled. Transformer coupling is
not supported.
The LMH0344 correctly handles equalizer pathological signals for standard definition and high definition serial digital
video, as described in SMPTE RP 178 and RP 198, respectively.
MUTE REFERENCE (MUTEREF)
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. As the applied MUTEREF voltage is increased, the
amount of cable that can be equalized before carrier detect is
de-asserted and the outputs are muted is decreased.
MUTEREF may be left unconnected for maximum equalization
before muting.
OUTPUT INTERFACING
The SDO and SDO outputs are internally loaded with 50Ω.
They produce a 750 mVP-P differential output, or a
375 mVP-P single-ended output.
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LMH0344
The PCB layout techniques in the application note apply to
the LMH0344 as well.
Application Information
PCB LAYOUT RECOMMENDATIONS
Please refer to the following Application Note on National's
website: AN-1372, “LMH0034 PCB Layout Techniques.”
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LMH0344
Physical Dimensions inches (millimeters) unless otherwise noted
16-Pin LLP
Order Number LMH0344SQ
NS Package Number SQB16A
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LMH0344 3Gbps HD/SD SDI Adaptive Cable Equalizer
Notes
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Copyright© 2007 National Semiconductor Corporation
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