LMH0024
3.3V SMPTE 259M / 344M Adaptive Cable Equalizer
General Description
The LMH0024 SMPTE 259M / 344M adaptive cable equal-
izer 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 sup-
ports SMPTE 259M and SMPTE 344M.
The LMH0024 implements DC restoration to correctly handle
pathological data conditions. DC restoration can be by-
passed for low data rate applications. The equalizer is flex-
ible 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.
Features
n
SMPTE 259M and SMPTE 344M compliant
n
Supports DVB-ASI at 270 Mbps
n
Data rates: 143 Mbps to 540 Mbps
n
Equalizes up to 350 meters of Belden 1694A at 270
Mbps
n
Manual bypass, cable length indicator, and output mute
n
Single-ended or differential input
n
50
differential outputs
n
Single 3.3V supply operation
n
Industrial temperature range: -40C to +85C
n
198mW typical power consumption with 3.3V supply
n
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
PRELIMINARY
February 2006
LMH0024
SMPTE
259M
/
344M
Adaptive
Cable
Equalizer
2006 National Semiconductor Corporation
DS201725
www.national.com
Absolute Maximum Ratings
(Note 1)
Supply Voltage
-0.5V to 3.6V
Input Voltage (all inputs)
-0.3V to V
CC
+0.3V
Storage Temperature Range
-65C to +150C
Junction Temperature
+150C
Lead Temperature
(Soldering 4 Sec)
+260C
Package Thermal Resistance
JA
16-pin SOIC
JC
16-pin SOIC
+115C/W
+105C/W
ESD Rating (HBM)
8kV
ESD Rating (MM)
250V
Recommended Operating
Conditions
Supply Voltage (V
CC
V
EE
)
3.3V
5%
Input Coupling Capacitance
1.0 F
AEC Capacitor (Connected between
AEC+ and AEC-)
1.0 F
Operating Free Air Temperature (T
A
)
-40C to +85C
DC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Notes 2, 3).
Symbol Parameter
Conditions
Reference
Min
Typ
Max
Units
V
CMIN
Input Common Mode Voltage
SDI, SDI
1.9
V
V
SDI
Input Voltage Swing
At LMH0024 input, (Notes 4, 6)
720
800
950
mV
P-P
V
CMOUT
Output Common Mode Voltage
SDO, SDO
V
CC
V
SDO
/2
V
V
SDO
Output Voltage Swing
50
load, differential
750
mV
P-P
CLI DC Voltage
0m cable
CLI
2.5
V
no signal
1.2
V
MUTE Input Voltage
Min to mute outputs
MUTE
3.0
V
Max to force outputs active
2.0
V
I
CC
Supply Current
(Note 7)
60
77
mA
LMH0024
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2
AC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Note 3).
Symbol Parameter
Conditions
Reference
Min
Typ
Max
Units
BR
SDI
Input Data Rate
SDI, SDI
143
540
Mbps
Maximum Equalized Cable
Length (with equalizer
pathological)
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
t
r
,t
f
Output Rise Time, Fall Time
20% 80%, (Note 4)
SDO, SDO
100
220
ps
Mismatch in Rise/Fall Time
(Note 4)
2
15
ps
t
OS
Output Overshoot
(Note 4)
1
5
%
R
OUT
Output Resistance
single-ended, (Note 5)
50
RL
IN
Input Return Loss
(Note 8)
SDI, SDI
15
18-20
dB
R
IN
Input Resistance
single-ended
1.3
k
C
IN
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 V
EE
= 0 Volts.
Note 3: Typical values are stated for V
CC
= +3.3V and T
A
= +25C.
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.
LMH0024
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3
Connection Diagram
20172503
16-Pin SOIC
Order Number LMH0024MA
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
V
CC
Positive power supply (+3.3V).
3
V
EE
Negative power supply (ground).
4
SDI
Serial data true input.
5
SDI
Serial data complement input.
6
V
EE
Negative power supply (ground).
7
AEC+
AEC loop filter external capacitor (1F) positive connection.
8
AEC-
AEC loop filter external capacitor (1F) negative connection.
9
BYPASS
Bypasses equalization and DC restoration when high. No equalization occurs in this mode.
10
NC
No connect.
11
V
EE
Negative power supply (ground).
12
SDO
Serial data complement output.
13
SDO
Serial data true output.
14
V
EE
Negative power supply (ground).
15
V
CC
Positive power supply (+3.3V).
16
MUTE
Output mute. To force SDO and SDO to mute, tie to V
CC
. 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.
LMH0024
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Block Diagram
20172502
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 dis-
abled.
The signals before and after the DC Restoration / Level
Control block are used to generate the Automatic Equal-
ization 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 1F 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.
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
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.
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 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 50
.
They produce a 750 mV
P-P
differential output, or a
375 mV
P-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.
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.
SUPPLY CURRENT VS. CABLE LENGTH
The supply current (I
CC
) 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.
LMH0024
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