Datasheet

D[15:0]P/N
FRAMEP/N
••• •••
T0527-02
DATACLKP/N
(DDR)
A
[15:0]
0
C
[15:0]
0
B
[15:0]
0
D
[15:0]
0
Parity Bit for
Data Block N – 1
High
Low
= Odd Parity
= Even Parity
Stop Point for
Data Block N – 1
Start Point for
Data Block N
D[15:0]P/N
FRAMEP/N
DATACLKP/N
(DDR)
A
[15:0]
x
C
[15:0]
x
B
[15:0]
x
D
[15:0]
x
Parity Bit for
Data Block N
High
Low
= Odd Parity
= Even Parity
Stop Point for
Data Block N
Start Point for
Data Block N + 1
Data Block N
DAC3484
www.ti.com SLAS749C –MARCH 2011–REVISED AUGUST 2012
Notes: Rising edge of FRAMEP/N indicates the beginning of data block.
Parity bit for the current data block is latched on falling edge of DATACLK after the start point for next data block.
Figure 82. DAC3484 Block Parity Check (Example shown with Word Wide Mode)
DAC3484 ALARM MONITORING
The DAC3484 includes a flexible set of alarm monitoring that can be used to alert of a possible malfunction
scenario. All the alarm events can be accessed either through the config5 register or through the ALARM pin.
Once an alarm is set, the corresponding alarm bit in register config5 must be reset through the serial interface to
allow further testing. The set of alarms includes the following conditions:
Zero check alarm
• Alarm_from_zerochk. Occurs when the FIFO write pointer has an all zeros pattern. Since the write pointer is a
shift register, all zeros will cause the input point to be stuck until the next sync event. When this happens a
sync to the FIFO block is required.
FIFO alarms
• alarm_from_fifo. Occurs when there is a collision in the FIFO pointers or a collision event is close.
– alarm_fifo_2away. Pointers are within two addresses of each other.
– alarm_fifo_1away. Pointers are within one address of each other.
– alarm_fifo_collision. Pointers are equal to each other.
Clock alarms
• clock_gone. Occurs when either the DACCLK or DATACLOCK have been stopped.
– alarm_dacclk_gone. Occurs when the DACCLK has been stopped.
– alarm_dataclk_gone. Occurs when the DATACLK has been stopped.
Pattern checker alarm
• alarm_from_iotest. Occurs when the input data pattern does not match the pattern key.
PLL alarm
• alarm_from_pll. Occurs when the PLL is out of lock.
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