Datasheet

Data Sheet AD9633
Rev. 0 | Page 29 of 40
Table 11. Flexible Output Test Modes
Output Test
Mode
Bit Sequence Pattern Name Digital Output Word 1 Digital Output Word 2
Subject to
Data
Format
Select Notes
0000 Off (default) N/A N/A N/A
0001 Midscale short
10 0000 0000 (10-bit)
1000 0000 0000 (12-bit)
N/A Yes
Offset binary
code shown
0010 +Full-scale short
11 1111 1111 (10-bit)
1111 1111 1111 (12-bit)
N/A Yes
Offset binary
code shown
0011 −Full-scale short
00 0000 0000 (10-bit)
0000 0000 0000 (12-bit)
N/A Yes
Offset binary
code shown
0100 Checkerboard
10 1010 1010 (10-bit)
1010 1010 1010 (12-bit)
01 0101 0101 (10-bit)
0101 0101 0101 (12-bit)
No
0101 PN sequence long
1
N/A N/A Yes PN23
ITU 0.150
X
23
+ X
18
+ 1
0110 PN sequence short
1
N/A N/A Yes PN9
ITU 0.150
X
9
+ X
5
+ 1
0111
One-/zero-word
toggle
11 1111 1111 (10-bit)
1111 1111 1111 (12-bit)
00 0000 0000 (10-bit)
0000 0000 0000 (12-bit)
No
1000 User input Register 0x19 to Register 0x1A Register 0x1B to Register 0x1C No
1001 1-/0-bit toggle
10 1010 1010 (10-bit)
1010 1010 1010 (12-bit)
N/A No
1010 1× sync
00 0011 1111 (10-bit)
0000 0111 1111 (12-bit)
N/A No
1011 One bit high
00 0000 0000 (10-bit)
0000 0000 0000 (12-bit)
N/A No
Pattern
associated with
the external pin
1100 Mixed frequency
10 0011 0011 (10-bit)
1000 0110 0111 (12-bit)
N/A No
1
All test mode options except PN sequence short and PN sequence long can support 10-bit to 12-bit word lengths to verify data capture to the receiver.
When the SPI is used, the DCO phase can be adjusted in 60°
increments relative to the data edge. This enables the user to
refine system timing margins if required. The default DCO+
and DCO− timing, as shown in Figure 2, is 90° relative to the
output data edge.
A 10-bit serial stream can also be initiated from the SPI. This
allows the user to implement and test compatibility to lower
resolution systems. When changing the resolution to a 10-bit
serial stream, the data stream is shortened.
In default mode, as shown in Figure 2, the MSB is first in the
data output serial stream. This can be inverted so that the LSB is
first in the data output serial stream by using the SPI.
There are 12 digital output test pattern options available that
can be initiated through the SPI. This is a useful feature when
validating receiver capture and timing. Refer to Tabl e 11 for the
output bit sequencing options available. Some test patterns have
two serial sequential words and can be alternated in various
ways, depending on the test pattern chosen. Note that some
patterns do not adhere to the data format select option. In
addition, custom user-defined test patterns can be assigned in
the 0x19, 0x1A, 0x1B, and 0x1C register addresses.
The PN sequence short pattern produces a pseudorandom bit
sequence that repeats itself every 2
9
− 1 or 511 bits. A descrip-
tion of the PN sequence and how it is generated can be found in
Section 5.1 of the ITU-T 0.150 (05/96) standard. The seed value
is all 1s (see Table 12 for the initial values). The output is a parallel
representation of the serial PN9 sequence in MSB-first format.
The first output word is the first 12 bits of the PN9 sequence in
MSB aligned form.
The PN sequence long pattern produces a pseudorandom bit
sequence that repeats itself every 2
23
− 1 or 8,388,607 bits. A
description of the PN sequence and how it is generated can be
found in Section 5.6 of the ITU-T 0.150 (05/96) standard. The
seed value is all 1s (see Table 12 for the initial values) and the
AD9633 inverts the bit stream with relation to the ITU standard.
The output is a parallel representation of the serial PN23 sequence
in MSB-first format. The first output word is the first 12 bits of
the PN23 sequence in MSB aligned form.
Table 12. PN Sequence
Sequence
Initial
Value
First Three Output Samples
(MSB First) Twos Complement
PN Sequence Short 0x7F8 0xBDF, 0x973, 0xA09
PN Sequence Long 0x7FF 0x7FE, 0x800, 0xFC0