GS3590 datasheet(20/118 Pages) SEMTECH

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GS3590

Final Data Sheet Rev.4



PDS-061414 September 2017

20 of 118

Semtech

Proprietary & Confidential

www.semtech.com

4.2.2 Upstream Launch Swing Compensation

The GS3590 Cable Equalizer has an automatic gain control circuit, that is optimized on

the assumption that the Cable Driver in the upstream device is SMPTE-compliant and

has a launch swing of 800mVpp ±10%. When the source amplitude is known to be

non-SMPTE compliant, a compensation adjustment can be made in the GS3590. The

GS3590 can adjust for launch swings in the range of 250mV to 1V in approximately

50mVppd increments. Upstream launch swing compensation can be adjusted through

the CFG_EQ_INPUT_LAUNCH_SWING_COMP parameter in control register 0x18. The

default parameter value is 80d (50h), which corresponds to a nominal launch swing of

800mVppd.

4.2.3 Carrier Detect, Squelch Control, and Loss of Signal

The GS3590 Cable Equalizer has highly-configurable carrier detection and squelching

capability. The carrier detection can be made more robust against spurious signals and

noise at the inputs and the squelch control can be configured and enabled to reduce

false outputs to low level signals such as crosstalk.

The GS3590 reports two separate carrier detect parameters—STAT_PRI_CD and

STAT_SEC_CD. They are described in Section 4.2.3.1 and Section 4.2.3.2 respectively.

Note: The parameters referred to within Section 4.2.3 to Section 4.2.3.2 are linked to

their respective registers in Table 4-1.

4.2.3.1 Primary Carrier Detection (STAT_PRI_CD) Configuration

Primary carrier detection (STAT_PRI_CD) can be configured for higher stability by

filtering-out longer transients or glitches. This can be achieved by increasing the

sampling window over which the signal is sampled and the number of samples required

to assert or de-assert it.

There are three configuration parameters that control assertion or de-assertion of

STAT_PRI_CD:

 CFG_CD_FILTER_SAMPLE_WIN

 CFG_FILTER_DEASSERT_CNT

 CFG_CD_FILTER_ASSERT_CNT



See Figure 4-1 for a visual representation of the STAT_PRI_CD configuration

parameters.

With the default values in place:

 An assertion (setting HIGH) of STAT_PRI_CD will take place after a valid signal is

present for ~6.5ms

 A de-assertion (setting LOW) of STAT_PRI_CD will take place after loss of a valid

signal for ~96ms

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