CLC014AJE National Semiconductor, CLC014AJE Datasheet - Page 10

• Manufacturer Part Number: CLC014AJE
• Description: 07B4822
• Manufacturer: National Semiconductor

Specifications of CLC014AJE

• Ic Function: Adaptive Cable Equalizer
• Supply Voltage Range: 4.5V To 5.5V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: SOIC
• No. Of Pins: 14
• Termination Type: SMD
• Rohs Compliant: No
• Filter Terminals: SMD
• Data Rate Max: 650Mbps
• Lead Free Status / Rohs Status: Not Compliant

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Output Interfacing
DIFFERENTIAL SOURCE-TERMINATED OUTPUT
INTERFACE
Figure 6 is similar to Figure 5 except that the termination is
provided at the source. This configuration may also be used
for single-ended applications. However, the unused output
must still be terminated as shown.
TERMINATING PHYSICALLY SEPARATED OUTPUTS
When the two outputs must be routed to physically separate
locations, the circuit in Figure 6 may be applied. Alterna-
tively, if load termination is desired, the circuit in Figure 7
may be used. The resistive divider network provides 75Ω
termination and establishes proper ECL levels. This circuit
consumes slightly more power than the previous circuits.
FIGURE 6. Differential Source Terminated
FIGURE 5. Differential Load Terminated
Output Interface
Output Interface
(Continued)
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Design Guidelines
SELECTING THE AUTOMATIC EQUALIZER CAPACITOR
The AEC capacitor sets the loop time constant τ for the
equalizer’s adaptive loop response time. The following for-
mula is used to set the loop time constant:
R is a conversion factor that is set by internal equalizer
parameters and cable length. For Belden 8281 coaxial
cable, the R values are (τ = µs, C
For example, a C
loop time constant of 2 µs at 200 meters of cable.
CONNECTION AND OPERATION OF CD AND MUTE
Carrier Detect (CD) is a CMOS output that indicates the
presence of equalized data from the filter. This CD output
can be connected to MUTE to suspend changes in the data
outputs DO and DO, if no valid signal exists. This simple
configuration prevents random output transitions due to
noise. For sparse transition patterns it is recommended that
a capacitor be connected to CD as shown in Figure 1.
Add a capacitor to pin 5 to slow the response time of Carrier
Detect when Carrier Detect is connected to MUTE. The
capacitor reduces sensitivity to pathological patterns. Patho-
logical patterns are defined as sparse data sequences with
few transitions.
OUTPUT EYE MONITOR OEM CONNECTIONS
The OEM is a high-speed, buffered output for monitoring the
equalized eye pattern prior to the output comparator. Its
output is designed to drive an AC-coupled 50Ω coaxial cable
with a series 50Ω backmatch resistor. The cable should be
terminated with 50Ω at the oscilloscope. Figure 1 shows a
schematic with a typical connection.
FIGURE 7. Alternative Load Terminated
100 meters
200 meters
300 meters
AEC
Length
τ = R • C
Cable
Output Interface
value of 100 pF results in an adaptive
AEC
R Value
(Ohms)
• 10
15000
20000
32000
AEC
−6
in pF):
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