DS90UR124Q_14 Datasheet, PDF (21/36 Pages) Texas Instruments – MHz DC-Balanced 24-Bit FPD-Link II Serializer and Deserializer Chipset

DS90UR124Q, DS90UR241Q
www.ti.com
SNLS231N – SEPTEMBER 2006 – REVISED MARCH 2013
SIGNAL QUALITY ENHANCERS
The DS90UR124 Deserializer supports two signal quality enhancers. The SLEW pin is used to increase the drive
strength of the LVCMOS outputs when driving heavy loads. SLEW allows output drive strength for high or low
current drive. Default setting is LOW for low drive at 2 mA and HIGH for high drive at 4 mA.
There are two types of Progressive Turn-On modes (Fixed and PTO Frequency Spread) to help reduce EMI,
simultaneous switching noise, and system ground bounce. The PTOSEL pin introduces bank skew in the
data/clock outputs to limit the number of outputs switching simultaneously. For Fixed-PTO mode, the Deserializer
ROUT[23:0] outputs are grouped into three groups of eight, with each group switching about 2 or 1 UI apart in
phase from RCLK for Group 1 and Groups 2, 3 respectively (see Figure 15). In the PTO Frequency Spread
mode, ROUT[23:0] are also grouped into three groups of eight, with each group is separated out of phase with
the adjacent groups (see Figure 16) per every 4 cycles. Note that in the PTO Frequency Spread operating mode
RCLK is also spreading and separated by 1 UI.
@SPEED-BIST TEST FEATURE
To assist vendors with test verification, the DS90UR241/DS90UR124 is equipped with built-in self-test (BIST)
capability to support both system manufacturing and field diagnostics. BIST mode is intended to check the entire
high-speed serial link at full link-speed, without the use of specialized and expensive test equipment. This feature
provides a simple method for a system host to perform diagnostic testing of both Serializer and Deserializer. The
BIST function is easily configured through the 2 control pins on the DS90UR124. When the BIST mode is
activated, the Serializer has the ability to transfer an internally generated PRBS data pattern. This pattern
traverses across interconnecting links to the Deserializer. The DS90UR124 includes an on-chip PRBS pattern
verification circuit that checks the data pattern for bit errors and reports any errors on the data output pins on the
Deserializer.
The @SPEED-BIST feature uses 2 signal pins (BISTEN and BISTM) on the DS90UR124 Deserializer. The
BISTEN and BISTM pins together determine the functions of the BIST mode. The BISTEN signal (HIGH)
activates the test feature on the Deserializer. After the BIST mode is enabled, all the data input channels
DIN[23:0] on the DS90UR241 Serializer must be set logic LOW or floating in order for Deserializer to start
accepting data. An input clock signal (TCLK) for the Serializer must also be applied during the entire BIST
operation. The BISTM pin selects error reporting status mode of the BIST function. When BIST is configured in
the error status mode (BISTM = LOW), each of the ROUT[23:0] outputs will correspond to bit errors on a cycle-
by-cycle basis. The result of bit mismatches are indicated on the respective parallel inputs on the ROUT[23:0]
data output pins. In the BIST error-count accumulator mode (BISTM = HIGH), an 8-bit counter on ROUT[7:0] is
used to represent the number of errors detected (0 to 255 max). The successful completion of the BIST test is
reported on the PASS pin on the Deserializer. The Deserializer's PLL must first be locked to ensure the PASS
status is valid. The PASS status pin will stay LOW and then transition to HIGH once a BER of 1x10^-9 is achieved
across the transmission link.
BACKWARDS COMPATIBLE MODE WITH DS90C241 AND DS90C124
The RAOFF pin allows a backward compatible mode with DS90C241/DS90C124 devices. To interface with either
DS90C241 Serializer or DS90C124 Deserializer, the RAOFF pin on DS90UR241 or DS90UR124 must be tied
HIGH to disable the additional LSFR coding. For normal operation directly with DS90UR241 to DS90UR124,
RAOFF pins are set LOW. See Table 1 and Table 2 for more details.
Copyright © 2006–2013, Texas Instruments Incorporated
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Product Folder Links: DS90UR124Q DS90UR241Q