Datasheet

BIST Wait

Step 1: Enable AT SPEED BIST by placing the

Deserializer in BIST by mode setting BISTEN = H

BIST Start

Step 2: Deserializer will setup Serializer and enable BIST

mode through Bidirectional control channel

communication and then reacquire forward channel clock

BIST Stop

Step 3: Stop AT SPEED BIST by turning off BIST

mode with BISTEN = L at the Deserializer.

Step 4: Place System in

Normal Operating Mode

BISTEN = L

Normal

Serializer MODE = 0 and Deserializer MODE = 1

Apply power for Serializer and Deserializer

DS92LX2121, DS92LX2122

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SNLS330I –MAY 2010–REVISED APRIL 2013

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.

Table 5. Oscillator Frequency Select

Freq Control Oscillator Range min (MHz) typ (MHz) max (MHz)

00 External PCLK 10 50

01 Internal 50

10 Internal 25

11 Internal 12.5

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.

Product Folder Links: DS92LX2121 DS92LX2122