LMH0074
LMH0074 SMPTE 259M / 344M Adaptive Cable Equalizer
Literature Number: SNLS277C
LMH0074
August 27, 2009
SMPTE 259M / 344M Adaptive Cable Equalizer
General Description
The LMH0074 SMPTE 259M / 344M Adaptive Cable Equal-
izer 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 125
Mbps to 540 Mbps and supports SMPTE 259M and SMPTE
344M.
The LMH0074 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 pro-
vided to mute the output at a selectable level of signal degra-
dation.
Features
■SMPTE 259M and SMPTE 344M compliant
■Supports DVB-ASI at 270 Mbps
■Data rates: 125 Mbps to 540 Mbps
■Equalizes up to 400 meters of Belden 1694A at 270 Mbps
■Manual bypass and output mute with a programmable
threshold
■Single-ended or differential input
■50Ω differential outputs
■Single 3.3V supply operation
■Industrial temperature range: −40°C to +85°C
■208mW typical power consumption with 3.3V supply
■Footprint compatible with the LMH0044 and the GS9074A
Applications
■SMPTE 259M and SMPTE 344M serial digital interfaces
■Serial digital data equalization and reception
■Data recovery equalization
Typical Application
30027501
© 2009 National Semiconductor Corporation 300275 www.national.com
LMH0074 SMPTE 259M / 344M Adaptive Cable Equalizer
Absolute Maximum Ratings (Note 1)
Supply Voltage −0.5V to 3.6V
Input Voltage (all inputs) −0.3V to VCC+0.3V
Storage Temperature Range −65°C to +150°C
Junction Temperature +150°C
Lead Temperature
(Soldering 4 Sec) +260°C
Package Thermal Resistance
θJA 16-pin LLP
θJC 16-pin LLP
+43°C/W
+9°C/W
ESD Rating (HBM) 8kV
ESD Rating (MM) 250V
Recommended Operating
Conditions
Supply Voltage (VCC – VEE) 3.3V ±5%
Input Coupling Capacitance 1.0 µF
AEC Capacitor (Connected between
AEC+ and AEC-) 1.0 µF
Operating Free Air Temperature (TA) −40°C to +85°C
DC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Notes 2, 3).
Symbol Parameter Conditions Reference Min Typ Max Units
VCMIN Input Common Mode Voltage SDI, SDI 1.9 V
VSDI Input Voltage Swing At LMH0074 input, (Notes 4, 6) 720 800 950 mVP−P
VCMOUT Output Common Mode Voltage SDO, SDO VCC –
VSDO/2 V
VSDO Output Voltage Swing 50Ω load, differential 750 mVP-P
MUTEREF DC Voltage (floating) MUTEREF 1.3 V
MUTEREF Range 0.7 V
CD Output Voltage Carrier not present CD 2.6 V
Carrier present 0.4 V
MUTE Input Voltage Min to mute outputs MUTE 3.0 V
Max to force outputs active 0.8 V
ICC Supply Current (Note 7) 63 77 mA
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LMH0074
AC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Note 3).
Symbol Parameter Conditions Reference Min Typ Max Units
BRMIN Minimum Input Data Rate SDI, SDI 125 Mbps
BRMAX Maximum Input Data Rate 540 Mbps
Jitter for various Cable Lengths
(with equalizer pathological)
270 Mbps, Belden 1694A,
400 meters (Note 4)
0.2 UI
270 Mbps, Belden 8281,
280 meters (Note 4) 0.2 UI
tr,tfOutput Rise Time, Fall Time 20% – 80%, (Note 4) SDO, SDO 100 220 ps
Mismatch in Rise/Fall Time (Note 4) 2 15 ps
tOS Output Overshoot (Note 4) 1 5 %
ROUT Output Resistance single-ended, (Note 5) 50 Ω
RLIN Input Return Loss (Note 8) SDI, SDI 15 18-20 dB
RIN Input Resistance single-ended 1.3 kΩ
CIN Input Capacitance single-ended, (Note 5) 1 pF
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: Specification is guaranteed by design.
Note 6: The maximum input voltage swing assumes a nonstressing, DC-balance 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 7: Supply current depends on the amount of cable being equalized. The current is highest for short cable and decreases as the cable length is increased.
Refer to Figure 1.
Note 8: Input return loss is dependent on board design. The LMH0074 meets this specification on the SD074 evaluation board from 5MHz to 1.5GHz.
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LMH0074
Connection Diagram
30027503
16-Pin LLP
Order Number LMH0074SQ
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.
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LMH0074
Block Diagram
30027502
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 dif-
ferential 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 Con-
trol 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.
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 apply-
ing 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.
CARRIER DETECT (CD) AND MUTE
Carrier detect CD indicates if a valid signal is present at the
LMH0074 input. If MUTEREF is used, the carrier detect thresh-
old will be altered accordingly. CD provides a high voltage
when no signal is present at the LMH0074 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 LMH0074
outputs. Applying a low input will force the outputs to be ac-
tive.
CD and MUTE may be tied together to automatically mute the
output when no input signal is present.
INPUT INTERFACING
The LMH0074 accepts either differential or single-ended in-
put. The input must be AC coupled. Transformer coupling is
not supported.
The LMH0074 correctly handles equalizer pathological sig-
nals for standard definition serial digital video, as described
in SMPTE RP 178.
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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LMH0074
Application Information
PCB LAYOUT RECOMMENDATIONS
Please refer to the following Application Note on National's
website: AN-1372, “LMH0034 PCB Layout Techniques.”
The PCB layout techniques in the application note apply to
the LMH0074 as well.
SUPPLY CURRENT VS. CABLE LENGTH
The supply current (ICC) depends on the amount of cable be-
ing equalized. The current is highest for short cable and
decreases as the cable length is increased. Figure 1 shows
supply current vs. Belden 1694A cable length for 270 Mbps
data.
30027515
FIGURE 1. Supply Current vs. Belden 1694A Cable
Length, 270 Mbps
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LMH0074
Physical Dimensions inches (millimeters) unless otherwise noted
16-Pin LLP
Order Number LMH0074SQ
NS Package Number SQB16A
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LMH0074
Notes
LMH0074 SMPTE 259M / 344M Adaptive Cable Equalizer
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