GS2994 Datasheet, PDF (13/20 Pages) Semtech Corporation – GS2994 Adaptive Cable Equalizer

3.2
3.0
2.8
2.6
2.4
2.2
2.0
0
50 100 150 200 250 300 350 400 450
Cable Length (m)
Figure 4-1: SQ_ADJ vs. Cable Length (VCC=3.3V, room temperature, 800mV launch swing)
4.5 Carrier Detect, Sleep, and Auto-Sleep
The GS2994 includes a SLEEP input pin, which allows the application interface to put the
GS2994 into a low-power sleep mode, consuming less than 30mW. Set the SLEEP pin
HIGH to place the chip in its sleep state. In this mode, the Carrier Detect output will still
function in order to detect valid Serial Digital Input.
The Carrier Detect output pin (CD) indicates the presence of a valid signal at the input of
the GS2994. When CD is LOW, the device has detected a valid input on SDI and SDI.
When CD is HIGH, the device has not detected a valid input.
The Carrier Detect output still functions when the GS2994 is in sleep mode, such that a
valid Serial Digital Input can be detected at all times. In the sleep state, the carrier detect
functionality requires that the GAIN_SEL input be set to 0.
Auto-Sleep can be enabled by connecting CD to SLEEP. When connected, the GS2994
will automatically go into standby mode when there is a loss of Serial Digital Input
signal.
NOTE 1: CD will only detect loss of carrier for data rates greater than 19Mb/s.
NOTE 2: If the maximum cable length is exceeded (set by the SQ_ADJ pin) and the
device is not in Bypass mode, the CD pin will not be driven LOW, even if a carrier is
present.
NOTE 3: If the CD is connected to SLEEP, SQ_ADJ should either be left open, or
connected to ground.
Table 4-2: Sleep Input Table
Sleep
0
1
Function
The GS2994 operates normally
The GS2994 enters sleep mode. CD
output remains valid
GS2994 GS2994 Adaptive Cable Equalizer
Data Sheet
53967 - 4
August 2012
13 of 20