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GS3471

Final Data Sheet Rev.4

PDS-060498

September 2017

25 of 179

Semtech

www.semtech.com

4.2.2 Device Reset

Note: On power-up, the device must be reset to operate correctly.

In order to initialize all internal operating conditions to their default states, hold the

RESET signal LOW for a minimum of treset = 1ms after all power supplies are stable. There

are no requirements for power supply sequencing.

When held in reset, all device outputs are driven to a high-impedance state, with the

exception of SDOUT. SDOUT continues normal operation during reset.

GSPI access is restored 10 clock cycles after RESET is de-asserted.

All output buffers (including the PCLK output), are set to high-impedance in Reset mode

(RESET = LOW).

Figure 4-3: Reset Pulse

4.3 Automatic (Adaptive) Cable Equalization

The GS3471 automatically adjusts its gain to equalize and restore signals received over

different lengths of coaxial cable having loss characteristics similar to Belden 8281 or

1694A.The device is designed to automatically equalize SMPTE SDI signal rates up to

2.97Gb/s and DVB-ASI signals at 270Mb/s.

The GS3471 has the ability to limit the reach of the device to one of four values through

its host interface. The default value is the maximum range. The maximum range of the

device is also a function of the detected data rate, so the maximum cable will not exceed

the supported reach for that rate.

4.3.1 Cable Length Indication

The GS3471 reports the input signal strength through the

CABLE_LENGTH_INDICATOR bits in the STATUS_REG_0 register, accessible through

the device's host interface. The Cable Length Indication (CLI) is a simple, numeric value

in the range from 0h to EFh. This number can be approximated as a cable length in

meters by applying one of the cable scaling factors shown in Table 4-3 below for some

commonly used coaxial cables.

Supply Voltage

RESET

treset

95% of Nominal Level

Nominal Level

Reset

treset

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