NSC LMH0034_07

LMH0034
SMPTE 292M / 259M Adaptive Cable Equalizer
General Description
Features
The LMH0034 SMPTE 292M / 259M adaptive cable equalizer
is a monolithic integrated circuit for equalizing 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 1.485 Gbps and supports
SMPTE 292M, SMPTE 344M and SMPTE 259M.
The LMH0034 implements DC restoration to correctly handle
pathological data conditions. DC restoration can be bypassed
for low data rate applications. The equalizer is flexible in allowing either single-ended or differential input drive.
Additional features include a combined carrier detect and output mute pin which mutes the output when no signal is
present. A programmable mute reference is used to mute the
output at a selectable level of signal degradation. A cable
length indicator is provided to determine the amount of cable
being equalized.
■ SMPTE 292M, SMPTE 344M and SMPTE 259M
compliant
■ Supports DVB-ASI at 270 Mbps
■ High data rates: 143 Mbps to 1.485 Gbps
■ Equalizes up to 200 meters of Belden 1694A at 1.485
Gbps or up to 400 meters of Belden 1694A at 270 Mbps
■ Manual bypass, cable length indicator, and output mute
■
■
■
■
■
with a programmable threshold
Single-ended or differential input
50Ω differential outputs
Single 3.3V supply operation
208mW typical power consumption with 3.3V supply
Replaces the GS1524 and GS1524A
Applications
■ SMPTE 292M, SMPTE 344M, and SMPTE 259M serial
digital interfaces
■ Serial digital data equalization and reception
■ Data recovery equalization
Typical Application
20173401
© 2007 National Semiconductor Corporation
201734
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LMH0034 SMPTE 292M / 259M Adaptive Cable Equalizer
June 2007
LMH0034
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 SOIC
θJC 16-pin SOIC
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
+115°C/W
+105°C/W
8kV
250V
DC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Notes 2, 3).
Symbol Parameter
Conditions
VCMIN
Input Common Mode Voltage
VSDI
Input Voltage Swing
VCMOUT
Output Common Mode Voltage
VSDO
Output Voltage Swing
50Ω load, differential
CLI DC Voltage
0m cable
Reference
Min
SDI, SDI
At LMH0034 input, (Notes 4, 6)
720
CLI
Max cable
MUTEREF
MUTEREF Range
CD/MUTE Output Voltage
Carrier not present
CD/MUTE
800
Supply Current
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950
750
mVP-P
2.5
V
1.6
V
1.3
V
0.7
V
2.6
V
3.0
(Note 7)
V
V
63
2
mVP−P
V
Max to force outputs active
ICC
V
0.4
Min to mute outputs
Units
VCC –
VSDO/2
Carrier present
CD/MUTE Input Voltage
Max
1.9
SDO, SDO
MUTEREF DC Voltage (floating)
Typ
2.0
V
77
mA
LMH0034
AC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Note 3).
Symbol Parameter
BRSDI
Jitter for various cable lengths
(with equalizer pathological)
tr,tf
Conditions
Input Data Rate
Reference
Min
SDI, SDI
143
Typ
Max
Units
1485
Mbps
270 Mbps, Belden 1694A,
400 meters (Note 4)
0.2
UI
270 Mbps, Belden 8281,
280 meters (Note 4)
0.2
UI
1.485 Gbps, Belden 1694A,
140 meters (Note 4)
0.25
UI
1.485 Gbps, Belden 8281,
100 meters (Note 4)
0.25
UI
1.485 Gbps, Belden 1694A,
200 meters (Note 4)
0.3
Output Rise Time, Fall Time
20% – 80%, (Note 4)
Mismatch in Rise/Fall Time
(Note 4)
tOS
Output Overshoot
ROUT
SDO, SDO
100
220
ps
2
15
ps
(Note 4)
1
5
%
Output Resistance
single-ended, (Note 5)
50
RLIN
Input Return Loss
(Note 8)
RIN
Input Resistance
single-ended
CIN
Input Capacitance
single-ended, (Note 5)
SDI, SDI
15
Ω
18-20
dB
1.3
kΩ
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 Figures 1, 2.
Note 8: Input return loss is dependent on board design. The LMH0034 meets this specification on the SD034 evaluation board from 5MHz to 1.5GHz.
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LMH0034
Connection Diagram
20173403
16-Pin SOIC
Order Number LMH0034MA
See NS Package Number M16A
Pin Descriptions
Pin #
Name
Description
1
CLI
Cable length indicator. Provides a voltage inversely proportional to the cable length being
equalized.
2
VCC
Positive power supply (+3.3V).
3
VEE
Negative power supply (ground).
4
SDI
Serial data true input.
5
SDI
Serial data complement input.
6
VEE
Negative power supply (ground).
7
AEC+
AEC loop filter external capacitor (1µF) positive connection.
8
AEC-
AEC loop filter external capacitor (1µF) negative connection.
9
BYPASS
Bypasses equalization and DC restoration when high. No equalization occurs in this mode.
10
MUTEREF
Mute reference. Determines the maximum cable to be equalized before muting. May be
unconnected for maximum equalization.
11
VEE
Negative power supply (ground).
12
SDO
Serial data complement output.
13
SDO
Serial data true output.
14
VEE
Negative power supply (ground).
15
VCC
Positive power supply (+3.3V).
16
CD/MUTE
Bi-directional carrier detect and output mute. CD/MUTE is high when no signal is present. If
unconnected, MUTE is controlled automatically by carrier detect. To force MUTE on, tie to VCC. To
disable MUTE, tie to GND. CD/MUTE has no function in BYPASS mode.
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LMH0034
Block Diagram
20173402
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.
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. 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 (MUTEREF).
The Output Driver produces SDO and SDO.
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 LMH0034 input. If MUTEREF is used, the
carrier detect threshold will be altered accordingly.
CD/MUTE provides a high voltage when no signal is present
at the LMH0034 input, and the outputs are automatically muted. CD/MUTE 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 LMH0034 outputs.
Applying a high input to CD/MUTE will mute the LMH0034
outputs. Applying a low input will force the outputs to be active
regardless of the length of cable or the state of MUTEREF.
INPUT INTERFACING
The LMH0034 accepts either differential or single-ended input. The input must be AC coupled. Transformer coupling is
not supported.
The LMH0034 correctly handles equalizer pathological signals for standard definition and high definition serial digital
video, as described in SMPTE RP 178 and RP 198, respectively.
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 (MUTEREF)
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 cable
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LMH0034
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.
Application Information
PCB LAYOUT RECOMMENDATIONS
Please refer to the following Application Note on National's
website: AN-1372, “LMH0034 PCB Layout Techniques.”
REPLACING THE GENNUM GS1524
The LMH0034 is form-fit-function compatible with the Gennum GS1524 and GS1524A.
SUPPLY CURRENT VS. CABLE LENGTH
The supply current (ICC) depends on the amount of cable being 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 1.485 Gbps
data and Figure 2 shows supply current vs. Belden 1694A
cable length for 270 Mbps data.
20173415
FIGURE 2. Supply Current vs. Belden 1694A Cable
Length, 270 Mbps
20173413
FIGURE 1. Supply Current vs. Belden 1694A Cable
Length, 1.485 Gbps
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LMH0034
Physical Dimensions inches (millimeters) unless otherwise noted
16-Pin SOIC
Order Number LMH0034MA
NS Package Number M16A
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LMH0034 SMPTE 292M / 259M Adaptive Cable Equalizer
Notes
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Copyright© 2007 National Semiconductor Corporation
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