DS32ELX0421SQX/NOPB National Semiconductor, DS32ELX0421SQX/NOPB Datasheet - Page 26

• Manufacturer Part Number: DS32ELX0421SQX/NOPB
• Description: IC SERIALIZER 312.5GBPS 48LLP
• Manufacturer: National Semiconductor

Specifications of DS32ELX0421SQX/NOPB

• Function: Serializer
• Data Rate: 3.125Gbps
• Input Type: LVDS
• Output Type: CML
• Number Of Inputs: 5
• Number Of Outputs: 2
• Voltage - Supply: 2.5V, 3.3V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LLP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: DS32ELX0421SQX

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Register Recipes
Many features of the serializer contained within the SMBus
registers require multiple writes to configure and enable. This
methodology was implemented to prevent accidental register
writes from causing undesired device behavior. Several
recipes for common features are listed below. When experi-
menting with other SMBus register features, be sure to read
through the register map for override and enable bits.
SCRAMBLER OVERRIDE CONTROL
The scrambler’s default settings are described in the device
configuration section. However, the scrambler’s setting can
be overridden if desired.
Reg 22’h, write 08’h
Reg 21’h, write to bit 3 to enable/disable
75Ω MODE
The serializer can be programmed to interface with 75Ω me-
dia by using the recipe shown below. The inverting serial
output should be terminated when interfacing with single end-
ed media.
Reg 2F’h, write 0 to bit 5
OUTPUT CHANNEL MUX CONTROL
DS32ELX0421 only. TxOUT0 is the output channel enabled
by default. By using the external pin TxOUT1_EN, TxOUT1
will be activated along with TxOUT0. If an application requires
that only one channel be active at a time, the following recipe
allows for each channel to be enabled or disabled indepen-
dent of the other.
Reg 2F’h, write 1’b to bit 2
Reg 2F’h, write to bits 1 or 0 to control the output channels
OUTPUT THE SERIAL CLOCK ON GPIO2
It is very helpful to be able to monitor high speed communi-
cation systems and observe their signal integrity. Generally,
26
this is done with a high speed real time oscilloscope or a
sampling oscilloscope. Sampling oscilloscopes require a ref-
erence clock to trigger on. The following recipe can be used
to bring out the serial clock on GPIO2 to provide a trigger for
sampling oscilloscopes.
Reg 04’h, write 21’h
Power Save Mode
When a system does not need to transmit high speed data
from the DS32EL0421 or DS32ELX0421, the power con-
sumption of the device can be managed as described in the
Power Management section on the Functional Description
page. The following recipe powers down many of the analog
and digital blocks in the serializer, but leaves the SMBus
module operational. Please note that in order to resume nor-
mal operation the recipe below will have to be unwritten.
Reg 01'h, write 10'h
Reg 26'h, write 40'h
Redundancy / Fail Over Configuration
DS32ELX0421 only. Implementing a redundancy system
with the DS32ELX0421 can be done in several ways. One
method would be to program the redundancy or fail over logic
into the host device or FPGA. The recipe below will describe
a different method, for which a DS32ELX0421 will communi-
cate to two different DS32EL0124 deserializers. The recipe
below will configure the DS32ELX0421 serializer to automat-
ically switch to the alternate output when the current high
speed link fails.
Configure all device with Remote Sense enabled either by pin
or register control.
Pull TxOUT1_EN pin high
reg 2F'h, write 2D'h
Reg 2F'h, write 28'h