m21315 Mindspeed Technologies, m21315 Datasheet - Page 13

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

The M21315 can also operate with a reference from an external clock buffer or oscillator instead of a crystal. The
M21315 can accept a single ended or differential 14.14 MHz reference clock. When driving the M21315 with a
single ended reference clock, the clock signal should be connected to the XTL_IN pin and the XTL_IN pin should
be left floating. If the XTL_IN pins on the M21315 are connected to a clock driver or oscillator, the requirements for
the signal connected to the M21315 are detailed in
Table 1-4.
1.2.2.5
Unlike the GS1575B, the loop filter for the M21315 reclocker is fully integrated into the part. As a result, LPF/LPF
pins are used for Mindspeed testing and should be left floating. This can be accomplished by not populating the
loop filter capacitor used with the GS1575B. As in the GS1575B, when LBW_INC =Floating, a lower bandwidth of
1.5 MHz for 1485 Mbps data rates and 0.52 MHz for 270 Mbps data rates is selected.
For other SD-SDI rates, the bandwidth scales proportionately to the bit rate, using the 270 Mbps as a reference
point. For example, at 540 Mbps, the bandwidth is 2x the 270 Mbps bandwidth. When LBW_INC = Low, the
bandwidth increases to 3.5 MHz for 1485 Mbps data rates and 1 MHz for 270 Mbps data rates.
Table 1-5.
1.2.2.6
A loss of lock alarm pin, LOL, is provided to indicate if the reclocker is in lock. When the reclocker has achieved
lock, LOL = High. If the reclocker is out of lock, LOL = Low. For synchronous switching at the same data rate, the
lock time is lower if a higher loop bandwidth is selected.
21315-DSH-001-B
Input Common Mode
Drive Impedance
NOTES:
1.
2.
3.
NOTE:
Typical values. Loop bandwidth scales to lower frequency with reduced data rates.
LBW_INC
When driving a reference clock single ended, connected the clock signl to the XTL_IN pin and leave the XTL_IN pin floating.
TTL Input levels are supported for 14.14 MHz reference frequency.
With a 14.14 MHz reference, the reference signal can be cascaded from one M21315 to another.
Differential input swing (p-p)
Single ended input swing (p-p)
0
1
Reference Clock/Oscillator Input Specifications
Loop Bandwidth Control Settings
Reclocker Loop Bandwidth
Loss of Lock Alarm
Mode
HD LOOP BANDWIDTH SETTING
1.5 MHz (default)
(1485 Mbps)
Mindspeed Technologies
3.5 MHz
Mindspeed Proprietary and Confidential
Table
1-4.
®
V
500mV
250mV
DD
Min
14.14 MHz Reference Frequency
-2.0
SD LOOP BANDWIDTH SETTING
0.52 MHz (default)
(270 Mbps)
1.0 MHz
Functional Description
V
DD
Max
60Ω
-1.2
7