DS92LX2121_14 Datasheet, PDF (27/43 Pages) Texas Instruments – 10 - 50 MHz DC-Balanced Channel Link III Bi-Directional Control Serializer and Deserializer

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Step 4: Place System in
Normal Operating Mode
BISTEN = L
DS92LX2121, DS92LX2122
SNLS330J – MAY 2010 – REVISED JANUARY 2014
Serializer MODE = 0 and Deserializer MODE = 1
Apply power for Serializer and Deserializer
Normal
Step 1: Enable AT SPEED BIST by placing the
Deserializer in BIST by mode setting BISTEN = H
BIST Wait
Step 2: Deserializer will setup Serializer and enable BIST
mode through Bidirectional control channel
communication and then reacquire forward channel clock
BIST Start
Step 3: Stop AT SPEED BIST by turning off BIST
mode with BISTEN = L at the Deserializer.
BIST Stop
Figure 30. AT-SPEED BIST System Flow Diagram
Step 1: Place the Deserializer in BIST Mode.
Serializer and Deserializer power supply must be supplied. Set the Serializer M/S pin to LOW and the
Deserializer M/S pin to HIGH. Enable the AT SPEED BIST mode on the Deserializer by setting the BISTEN pin
High. The DS92LX2122 GPIO[1:0] pins are used to select the PCLK frequency of the on-chip oscillator for the
BIST test on high speed data path.
Freq Control
00
01
10
11
Table 5. Oscillator Frequency Select
Oscillator Range
External PCLK
Internal
Internal
Internal
min (MHz)
10
typ (MHz)
50
25
12.5
max (MHz)
50
The Deserializer GPIO[1:0] set to 00 will bypass the on-chip oscillator and an external oscillator to Serializer
PCLK input is required. This allows the user to operate BIST under different frequencies other than the
predefined ranges.
Step 2: Enable AT SPEED BIST by placing the Serializer into BIST mode.
Deserializer will communicate through the back-channel to configure Serializer into BIST mode. Once the BIST
mode is set, the Serializer will initiate BIST transmission to the Deserializer.
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