LMH0394_15 Datasheet, PDF (13/35 Pages) Texas Instruments – 3G HD/SD SDI Low Power Extended Reach Adaptive Cable Equalizer

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Feature Description (continued)
LMH0394
SNLS312M – AUGUST 2010 – REVISED JULY 2015
Coaxial Cable
75:
5.6 nH
1.0 PF
SDI
SDO
1.0 PF ^LMH0394
SDI
SDO
75:
37.4:
100: Differential T-Line
SDI
LMH0346
100:
3G/HD/SD
SDI Reclocker
SDI
Figure 8. DC Output Interface to LMH0346 Reclocker
Coaxial Cable
75:
5.6 nH
1.0 PF
SDI
SDO
1.0 PF ^LMH0394
SDI
SDO
75:
37.4:
100: Differential T-Line
SDI0
LMH0356
3G/HD/SD
SDI Reclocker
SDI0
Figure 9. DC Output Interface to LMH0356 Reclocker
7.4 Device Functional Modes
The LMH0394 supports two modes of operation. In pin mode, the LMH0394 operates with control pins to set its
operating state and is footprint compatible with the LMH0384, LMH0344, and legacy SDI equalizers. In SPI
mode, an optional SPI serial interface can be used to access and configure multiple LMH0394 devices in a
daisy-chain configuration.
7.4.1 Auto Sleep
The auto sleep mode allows the LMH0394 to power down when no input signal is detected. If the AUTO SLEEP
pin is set high, the LMH0394 goes into a deep power-save mode when no signal is detected. The device powers
on again once an input signal is detected. The auto sleep functionality can be turned off by setting AUTO SLEEP
low or tying this pin to ground. An additional auto sleep setting available in SPI mode can be used to force the
equalizer to power down regardless of whether there is an input signal or not. Auto sleep has precedence over
mute and bypass modes.
In auto sleep mode, the time to power down the equalizer when the input signal is removed is less than 200 µs
and should not have any impact on the system timing requirements. The device will wake up automatically once
an input signal is detected, and the delay between signal detection and full functionality of the equalizer is
negligible (about 5 ms). The overall system will be limited only by the settling time constant of the equalizer
adaptation loop.
Copyright © 2010–2015, Texas Instruments Incorporated
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