SD014EVK National Semiconductor, SD014EVK Datasheet - Page 10

• Manufacturer Part Number: SD014EVK
• Description: BOARD EVALUATION CLC014
• Manufacturer: National Semiconductor

Specifications of SD014EVK

• Design Resources: SD014EVK Schematic
• Main Purpose: Interface, Cable Equalizer
• Utilized Ic / Part: CLC014
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

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TERMINATING PHYSICALLY SEPARATED OUTPUTS
When the two outputs must be routed to physically separate
locations, the circuit in
if load termination is desired, the circuit in
used. The resistive divider network provides 75Ω termination
and establishes proper ECL levels. This circuit consumes
slightly more power than the previous circuits.
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 pa-
rameters and cable length. For Belden 8281 coaxial cable,
the R values are (τ = μs, C
FIGURE 6. Differential Source Terminated
FIGURE 7. Alternative Load Terminated
100 meters
200 meters
300 meters
Length
Cable
τ = R • C
Output Interface
Output Interface
Figure 6
AEC
AEC
in pF):
may be applied. Alternatively,
R Value
(Ohms)
• 10
15000
20000
32000
100056 Version 11 Revision 6
−6
Figure 7
10005626
10005627
may be
10
Print Date/Time: 2010/08/23 16:48:25
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 out-
puts DO and DO, if no valid signal exists. This simple config-
uration prevents random output transitions due to noise. For
sparse transition patterns it is recommended that a capacitor
be connected to CD as shown in
Add a capacitor to pin 5 to slow the response time of Carrier
Detect when Carrier Detect is connected to MUTE. The ca-
pacitor reduces sensitivity to pathological patterns. Patholog-
ical 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 out-
put is designed to drive an AC-coupled 50Ω coaxial cable with
a series 50Ω backmatch resistor. The cable should be termi-
nated with 50Ω at the oscilloscope.
schematic with a typical connection.
MINIMUM DATA TRANSITIONS
The CLC014 specifies a minimum transition rate. For the
CLC014 this sets the minimum data rate for transmitting data
through any cable medium. The CLC014 minimum average
transition density is found in the Electrical Characteristics
section of the datasheet.
POWER SUPPLY OPERATION AND THERMAL
CONSIDERATIONS
The CLC014 operates from either +5V or −5.2V single sup-
plies. Refer to
When operating with a −5.2V supply, the V
bypassed to ground. The evaluation board and associated
literature provide for operation from either supply.
Maximum power dissipation occurs at minimum cable length.
Under that condition, I
Total power dissipated:
Power in the load:
Maximum power dissipated on the die:
Junction Temperature =
(θ
P
P
P
T
L
DMAX
JA
= (58 mA)(5V) = 290 mW
= (0.7V)(11 mA) + (37.5)(11 mA)
)(278 mW) + T
= P
T
–P
Figure 1
L
AEC
= 278 mW
A
value of 100 pF results in an adaptive
CC
= T
when operating the part from +5V.
= 58 mA.
A
+ 26°C
Figure
2
= 12 mW
1.
Figure 1
EE
pins should be
shows a