m21330 Mindspeed Technologies, m21330 Datasheet - Page 23

• Manufacturer Part Number: m21330
• Description: 4.25 Gbps Quad-channel Cable Driver And Adaptive Equalizer With 4x4 Crosspoint Switch
• Manufacturer: Mindspeed Technologies

5.8
To avoid random chattering of the output due to noise when there is no signal present at the inputs, the M21330
includes a squelch feature to automatically inhibit the output when there is a LOS alarm. This feature can be
disabled if desired, and there is an option to inhibit to either logic H, logic L, or the EI common mode level on
squelch. In addition to the automatic squelch feature, a manual squelch can be forced using register 0Bh. LOS
should be set to "never squelch" when the EI circuit is enabled to allow the device to detect data bursts quickly after
electrical idle periods that last longer than approximately 5 us.
5.9
Pathological data patterns found in SDI digital video applications stress the control circuitry in the adaptive
equalization loops of the M21330 and limit the equalization performance of the device. For this reason, the
adaptive equalization of the M21330 should be disabled and the manual equalization mode of the device should be
used in SDI video applications. With the M21330 in manual equalization mode, the device can pass pathological
video data error-free for SD-SDI, HD-SDI, and 3G-SDI data rates. In addition to putting the device into manual
equalization mode, the following register settings should be set in applications when the device is used with
pathological video data patterns.
Table 5-2.
For optimum performance with long strings of consecutive bits found in pathological patterns, 4.7 µF or larger value
AC coupling capacitors should be used on the inputs and outputs of the M21330.
21330-DSH-001-B
Equalizer Configuration
Input 1/0 Manual
Equalization Setting
Input 3/2 Manual
Equalization Setting
SDI Video Configuration A, Input 0
SDI Video Configuration A, Input 1
SDI Video Configuration A, Input 2
SDI Video Configuration A, Input 3
SDI Video Configuration B, Input 0
SDI Video Configuration A, Input 1
SDI Video Configuration B, Input 2
SDI Video Configuration B, Input 3
Register Name
Recommended Register Settings for SDI Video Applications
Squelch
Operation in SDI Video Applications
Register
Address
02h
04h
05h
24h
25h
26h
27h
28h
29h
2Ah
2Bh
Mindspeed Technologies
Default Value
C0h
77h
77h
00h
00h
00h
00h
00h
00h
00h
00h
40h
Determined by the
system channel
Determined by the
system channel
F0h
F0h
F0h
F0h
40h
40h
40h
40h
Recommended Value
®
Set manual equalization level
Set manual equalization level
Enable manual setting of low
frequency gain
Enable manual setting of low
frequency gain
Enable manual setting of low
frequency gain
Enable manual setting of low
frequency gain
Disable adaptive equalization
Increase low frequency gain
Increase low frequency gain
Increase low frequency gain
Increase low frequency gain
Functional Description
Description
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