m21315 Mindspeed Technologies, m21315 Datasheet - Page 14

• Manufacturer Part Number: m21315
• Description: M21315 Hd/sd-sdi Auto-rate Reclocker W/4 1 Selector
• Manufacturer: Mindspeed Technologies

1.2.2.7
The reclocker is designed to operate in two modes. In the first mode, with ARD_EN = High, the Auto Rate Detect
is enabled which automatically locks the CDR to the rates typically used in SD-SDI, HD-SDI, and DVB-ASI
applications. The locked data rate is then reported with the RATE[2:0] pins as shown in
The M21315 does not have any of the false lock issues exhibited by the GS1535 or the GS1575B with DVB/ASI 8b/
10b encoded data or idle patterns; however, for backwards compatibility, it is possible to lock out the 177 Mbps data
rate by setting 177_L/O = High which removes 177Mbps from the ARD search sequence.
Note that this pin is only active if ARD_EN = High. With the ARD disabled (ARD_EN = Low), the reclocker locking
frequency is forced by using the RATE[2:0] pins as inputs and selecting the data rate as shown in
Table 1-6.
Table 1-7.
For system reporting purposes as well as to set the output slew rate on the cable drivers, the SD/HD output is used
to indicate if the reclocker has locked to a HD rate. For SD-SDI rates, SD/HD = High and for the HD-SDI rate SD/
HD =Low. This pin is used to set the output slew rate of the downstream cable driver.
177_L/O = High would remove the 177 Mbps rate from the search sequence resulting in a slightly faster
asynchronous lock time but as there are not any false locking issues with DVB-ASI with the M21315 this is not
required.
Also, if the M21315 is out-of-lock, the search pattern will not start unless the M21315 detects that there are
transitions in the data through an internal loss of signal detector.
1.2.2.7.1
The reclocker can be forced into the bypass mode (input data to output without retiming) with MAN_BYPASS =
High. With MAN_BYPASS = Low (normal operation), AUTO_BYPASS = High enables the auto bypass mode that
puts the reclocker into the bypass mode whenever LOL = Low (ie. the reclocker is out of lock).
21315-DSH-001-B
RATE[2:0]
RATE[2:0]
000b
001b
010b
011b
100b
101b
000b
001b
010b
011b
100b
101b
Rate Report Mapping when ARD is Enabled
Rate Select with ARD Disabled
Auto Rate Detect (ARD)
Bypass and DDO_MUTE
Mindspeed Technologies
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1485/1483.5 Mbps
1485/1483.5 Mbps
143 Mbps
177 Mbps
270 Mbps
360 Mbps
540 Mbps
143 Mbps
177 Mbps
270 Mbps
360 Mbps
540 Mbps
Bit Rate
Bit Rate
®
Functional Description
Table
1-6.
Table
1-7.
8