50:

SDO, SCO/SDO2

VCC

VCC

50:

VCC

SDO, SCO/SDO2

LMH0026

www.ti.com

SNLS253B – MARCH 2008 – REVISED APRIL 2013

Figure 3. Equivalent SDO Output Circuit (SDO, SDO, SCO/SDO2, SCO/SDO2)

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 serial data output or a low jitter differential clock output appropriate 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 data-rate 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 (serial 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, 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

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 1.

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 1. 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 1. BYPASS/AUTO BYPASS has an internal pull-

down device.

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