NSC LMH0024MA

February 2006
LMH0024
3.3V SMPTE 259M / 344M Adaptive Cable Equalizer
General Description
Features
The LMH0024 SMPTE 259M / 344M 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 540 Mbps and supports SMPTE 259M and SMPTE 344M.
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The LMH0024 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 mute pin which can be used to
manually mute the output and a cable length indicator which
determines the amount of cable being equalized.
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SMPTE 259M and SMPTE 344M compliant
Supports DVB-ASI at 270 Mbps
Data rates: 143 Mbps to 540 Mbps
Equalizes up to 350 meters of Belden 1694A at 270
Mbps
Manual bypass, cable length indicator, and output mute
Single-ended or differential input
50Ω differential outputs
Single 3.3V supply operation
Industrial temperature range: −40˚C to +85˚C
198mW typical power consumption with 3.3V supply
Footprint compatible with the LMH0034 and the GS9064
Applications
n SMPTE 259M and SMPTE 344M serial digital interfaces
n Serial digital data equalization and reception
n Data recovery equalization
Typical Application
20172501
© 2006 National Semiconductor Corporation
DS201725
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LMH0024 SMPTE 259M / 344M Adaptive Cable Equalizer
PRELIMINARY
LMH0024
Absolute Maximum Ratings (Note 1)
Supply Voltage
Input Voltage (all inputs)
Storage Temperature Range
Recommended Operating
Conditions
−0.5V to 3.6V
−0.3V to VCC+0.3V
Supply Voltage (VCC – VEE)
3.3V ± 5%
−65˚C to +150˚C
Input Coupling Capacitance
1.0 µF
Junction Temperature
+150˚C
Lead Temperature
(Soldering 4 Sec)
AEC Capacitor (Connected between
AEC+ and AEC-)
1.0 µF
+260˚C
Operating Free Air Temperature (TA)
−40˚C to +85˚C
Package Thermal Resistance
θJA 16-pin SOIC
θJC 16-pin SOIC
+115˚C/W
+105˚C/W
ESD Rating (HBM)
8kV
ESD Rating (MM)
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
Conditions
Reference
At LMH0024 input, (Notes 4, 6)
VCMOUT Output Common Mode Voltage
VSDO
Min
SDI, SDI
50Ω load, differential
CLI DC Voltage
0m cable
MUTE Input Voltage
Min to mute outputs
720
CLI
no signal
800
Supply Current
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V
950
(Note 7)
750
mVP-P
2.5
V
V
3.0
V
60
2
mVP−P
V
1.2
MUTE
Units
VCC –
VSDO/2
Max to force outputs active
ICC
Max
1.9
SDO, SDO
Output Voltage Swing
Typ
2.0
V
77
mA
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Note 3).
Symbol Parameter
BRSDI
Maximum Equalized Cable
Length (with equalizer
pathological)
tr,tf
Conditions
Input Data Rate
Reference
Min
SDI, SDI
143
Typ
Max
Units
540
Mbps
270 Mbps, Belden 1694A,
0.2UI output jitter, (Note 4)
350
m
270 Mbps, Belden 8281,
0.2UI output jitter, (Note 4)
280
m
540 Mbps, Belden 1694A,
0.2UI output jitter, (Note 4)
250
m
540 Mbps, Belden 8281,
0.2UI output jitter, (Note 4)
180
m
Output Rise Time, Fall Time
20% – 80%, (Note 4)
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)
RLIN
Input Return Loss
(Note 8)
RIN
Input Resistance
single-ended
CIN
Input Capacitance
single-ended, (Note 5)
SDO, SDO
SDI, SDI
15
50
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 Figure 1.
Note 8: Input return loss is dependent on board design. The LMH0024 meets this specification on the SD034 evaluation board from 5MHz to 1.5GHz.
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LMH0024
AC Electrical Characteristics
LMH0024
Connection Diagram
20172503
16-Pin SOIC
Order Number LMH0024MA
See NS Package Number M16A
Pin Descriptions
Pin #
1
Name
Description
CLI
Cable length indicator. Provides a voltage inversely proportional to the cable length being
equalized.
Positive power supply (+3.3V).
2
VCC
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
NC
No connect.
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
MUTE
Output mute. To force SDO and SDO to mute, tie to VCC. To disable MUTE, tie to GND.
Typical application is MUTE tied to GND to enable the outputs. MUTE must be tied either high
or low; it may not be left unconnected.
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LMH0024
Block Diagram
20172502
INPUT INTERFACING
The LMH0024 accepts either differential or single-ended
input. The input must be AC coupled. Transformer coupling
is not supported.
The LMH0024 correctly handles equalizer pathological signals for standard definition serial digital video, as described
in SMPTE RP 178.
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 Output Driver produces SDO and SDO. SDO and SDO
may be force to mute by activating MUTE.
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 for the CLC034
on National’s website: AN-1372, “CLC034 PCB Layout
Techniques.” The PCB layout techniques in this application
note apply to the LMH0024 as well.
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.
REPLACING THE GENNUM GS9064
The LMH0024 is footprint compatible with the Gennum
GS9064. Pin 16 (MUTE) of the LMH0024 must be connect to
ground for correct operation.
MUTE
MUTE can be used to manually mute or enable the
LMH0024 outputs. MUTE must be tied to a low-level input or
ground for SDO and SDO to be active. Applying a high input
to MUTE will mute the LMH0024 outputs.
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 270 Mbps
data.
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LMH0024
Application Information
(Continued)
20172515
FIGURE 1. Supply Current vs. Belden 1694A Cable
Length, 270 Mbps
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LMH0024 SMPTE 259M / 344M Adaptive Cable Equalizer
Physical Dimensions
inches (millimeters) unless otherwise noted
16-Pin SOIC
Order Number LMH0024MA
NS Package Number M16A
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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