ISL54100A_14 Datasheet, PDF (10/21 Pages) Intersil Corporation – TMDS Regenerators with Multiplexers

ISL54100A, ISL54101A, ISL54102A
Register Listing (Continued)
ADDRESS REGISTER (DEFAULT VALUE)
0x03
Input Control (0x12)
Recommended default: 0x62
BIT(S) FUNCTION NAME
DESCRIPTION
0 Tri-state Unselected 0: Normal Operation
Clock Inputs
1: Termination of unselected TMDS clock inputs is tri-stated
to save power. Setting this bit will disable the activity detect
function. This bit should not be set in crosspoint
configuration because it will make the clock termination
resistance variable depending on which 2 inputs are
selected. In general, this bit should always be set to 0.
1 Tri-state Unselected 0: Normal Operation
Data Inputs
1: Unselected Data inputs are tri-stated to save power. This
bit should not be set in crosspoint configuration because it
will make the data input termination resistance variable
depending on which 2 inputs are selected. (default)
2 Tri-state Selected 0: Selected Clock inputs are terminated into
Clock Inputs
50Ω/100Ω.
1: Selected Clock inputs are tri-stated (to allow chip to
operate in parallel with another TMDS receiver with fixed
50Ω termination)
3 Tri-state Selected 0: Selected Data inputs are terminated into
Data Inputs
50Ω/100Ω.
1: Selected Data inputs are tri-stated (to allow chip to
operate in parallel with another TMDS receiver with fixed
50Ω termination)
4 Activity Detect Mode 0: AC Activity. Activity detection is based on the presence of
AC activity on TMDS clock inputs. This setting (along with a
hysteresis of 20mV enabled) provides reliable activity
detection. (recommended setting)
1: Common Mode Voltage. If the common mode voltage is
above ~3.05V, the input is considered inactive. This method
has been found to be unreliable with small signal swings and
should not be used. This setting is the silicon default but
should be changed in software for more reliable activity
detection.
5 Clock Rx Hysteresis Enables hysteresis for the clock inputs to prevent false clock
detection when both inputs are high. Data inputs do not get
hysteresis.
0: TMDS input hysteresis disabled
1: TMDS input hysteresis enabled. Eliminates false activity
detects on unconnected channels. (recommended setting)
6 Clock Rx Hysteresis Controls the amount of hysteresis in the clock inputs.
Magnitude
0: 10mV
1: 20mV (recommended setting)
7 Recalibrate
0: Normal Operation
1: Recalibrates termination resistance. To recalibrate, take
this bit high, wait at least 1ms, then take this bit low.
Calibration is automatically done after power-on, but
performing a recalibration after the supply voltage and
temperature have stabilized may result in termination
resistances closer to the desired 50Ω.
10
FN6725.0
June 17, 2008