LMH0346MH/NOPB National Semiconductor, LMH0346MH/NOPB Datasheet - Page 9

• Manufacturer Part Number: LMH0346MH/NOPB
• Description: IC RECLOCKER HD/SD SDI 20-TSSOP
• Manufacturer: National Semiconductor
• Type: Reclockerr

Specifications of LMH0346MH/NOPB

• Package / Case: 20-TSSOP Exposed Pad, 20-eTSSOP, 20-HTSSOP
• Mounting Type: Surface Mount
• Applications: SDTV/HDTV
• Operating Temperature (min): -40C
• Operating Temperature Classification: Industrial
• Operating Temperature (max): 85C
• Package Type: TSSOP EP
• Rad Hardened: No
• Leaded Process Compatible: Yes
• Rohs Compliant: Yes
• Peak Reflow Compatible (260 C): Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LMH0346MH

OPERATING SERIAL DATA RATES
This device operates at serial data rates of 270 Mbps, 1483
Mbps, 1485 Mbps, 2967 Mbps, and 2970 Mbps. The device
does not lock to harmonics of these rates. The device does
not lock and automatically enters the reclocker bypass mode
for the following data rates: 143 Mbps, 177 Mbps, 360 Mbps,
and 540 Mbps.
SERIAL DATA CLOCK/SERIAL DATA 2 OUTPUT
The Serial Data Clock/Serial Data 2 Output is controlled by
the SCO_EN input and provides either a second retimed se-
rial data output or a low jitter differential clock output appro-
priate to the serial data rate being processed. When operating
as a serial clock output, the rising edge of the clock will be
positioned within the corresponding serial data bit interval
within 10% of the center of the data interval.
Differential output SCO/SDO2 functions as the second serial
data output when the SCO_EN input is a logic-low level. This
output functions as the serial clock output when the SCO_EN
input is a logic-high level. The SCO_EN input has an internal
pull-down device and the default state of SCO_EN is low (se-
rial data output 2 enabled). SCO/SDO2 is muted when the
OUTPUT MUTE input is a logic low level. When the Bypass
mode is activated and this output is functioning as a serial
clock output (SCO_EN is high), the output will also be muted.
If an unsupported data rate is used while in Auto Bypass mode
with this output functioning as a serial clock output, the output
is invalid.
Control Inputs and Indicator
Outputs
SERIAL DATA RATE SELECTOR
The Serial Data Rate Selector (RATE [1:0]) permits the user
to fix the operating serial data rate. The pins have internal pull-
downs which maintain a logic-low input condition unless ex-
ternally driven to a logic-high condition. This input also serves
to place the device in a test mode. The codes shown in
Table 1
LMH0346 then enters either the Auto-Rate Detect mode or a
single operating rate. Selecting the 270 Mbps rate mode may
also be used when reclocking DVB-ASI data. DVB-ASI data
is MPEG2 coded data that is transmitted in 8B10B coding.
The device will reclock this data without harmonic locking.
select the desired operating serial data rate. The
FIGURE 2. Equivalent SDO Output Circuit (SDO, SDO, SCO/SDO2, SCO/SDO2)
9
Auto-Rate Detect mode may be used for any supported data
rate, including DVB-ASI.
LOCK DETECT
The Lock Detect (LD) output, when high, indicates that data
is being received and the PLL is locked. LD may be connected
to the OUTPUT MUTE input to mute the data and clock out-
puts when no data signal is being received. Note that when
the Bypass/Auto Bypass input is set high, Lock Detect will
remain low. See
OUTPUT MUTE
The OUTPUT MUTE input, when low, mutes the serial data
and clock outputs. It may be connected to Lock Detect or ex-
ternally driven to mute or un-mute the outputs. If OUTPUT
MUTE is connected to LD, then the data and clock outputs
are muted when the PLL is not locked. This function overrides
the Bypass function: see
internal pull-up device to enable the output by default.
BYPASS/AUTO BYPASS
The Bypass/Auto Bypass input, when high, forces the device
to output the data without reclocking it. When this input is low,
the device automatically bypasses the reclocking function
when the device is in an unlocked condition or the detected
data rate is a rate which the device does not support. Note
that when the Bypass/Auto Bypass input is set high, Lock
Detect will remain low. See
PASS has an internal pull-down device.
Rate [1:0]
Code
00
01
10
TABLE 1. Data Rate Select Input Codes
Auto-Rate
Detect
mode
270 Mbps
1483/1485
Mbps,
2967/2970
Mbps
Data Rate
or Mode
Table
2.
Table
May be used to support DVB-
ASI operation
Table
20215009
2. OUTPUT MUTE has an
2. BYPASS/AUTO BY-
Comments
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