LMH0036 Datasheet, PDF (9/19 Pages) National Semiconductor (TI) – SD SDI Reclocker with 4:1 Input Multiplexer

LMH0036
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Control Inputs and Indicator Outputs
SNLS254B – MARCH 2008 – REVISED APRIL 2013
SERIAL DATA INPUT SELECTOR
The Serial Data Input Selector (SEL [1:0]) allows the user to select the active input channel. Table 1 shows the
input selected for a given state of SEL [1:0].
SEL [1:0] Code
00
01
10
11
Table 1. Data Input Select Codes
Selected Input
SDI0
SDI1
SDI2
SDI3
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 outputs when no data signal is being
received. Note that when the Bypass/Auto Bypass input is set high, Lock Detect will remain low. See Table 2.
OUTPUT MUTE
The OUTPUT MUTE input, when low, mutes the serial data and clock outputs. It may be connected to Lock
Detect or externally 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
Table 2. OUTPUT MUTE has an 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 Table 2. BYPASS/AUTO BYPASS has an internal pull-
down device.
LOCK DETECT
0
1
X
0
1
OUTPUT MUTE
1
1
0
LOCK DETECT
LOCK DETECT
Table 2. Control Functionality
BYPASS/AUTO BYPASS
X
0
X
X
0
DEVICE STATUS
PLL unlocked, reclocker bypassed
PLL locked to supported data rate, reclocker not bypassed
Outputs muted
Outputs muted
PLL locked to supported data rate, reclocker not bypassed
SD
The SD output indicates that the LMH0036 is locked and processing SD data rates. It may be used to control
another device such as the LMH0002 cable driver. When this output is high it indicates that the data rate is 270
Mbps. The SD output is a registered function and is only valid when the PLL is locked and the Lock Detect
output is high. The SD output is undefined for a short time after lock detect assertion or de-assertion due to a
data change on the SDI input. See Figure 4 for a timing diagram showing the relationship between SDI, Lock
Detect, and SD.
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