LMH0366

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SNAS585D – APRIL 2012 – REVISED APRIL 2013

Functional Description

The LMH0366 is a multi-rate reclocker for serial digital video data and operates at 125 Mbps, 270 Mbps, 1.4835

Gbps, 1.485 Gbps, 2.967 Gbps, and 2.97 Gbps. The LMH0366 recovers the serial clock and retimes the serial

data stream to suppress accumulated jitter.

Modes of Operation

The LMH0366 has two modes of operation: pin mode (SPI_EN = 0) and SPI mode (SPI_EN = 1).

In pin mode, the LMH0366 functions are controlled by control pins only.

SPI mode allows access to SPI registers for controlling all LMH0366 features, including additional features such

as:

•

Eye opening monitor

•

Output driver amplitude, common mode voltage, and de-emphasis controls

•

Input signal detection

•

More control over which signals are sent to the output drivers

•

Full details of the locked data rate

•

Ability to distinguish between 1.4835 and 1.485 Gbps, and between 2.967 and 2.97 Gbps (in external

reference mode)

•

Ability to configure device pins as GPIOs

•

Ability to power down unused features for power savings

The LMH0366 SPI protocol is described in the SPI Register Access section.

Four device pins are dual mode and change functionality depending on whether the device is in pin mode or SPI

mode, as indicated in Table 1.

Table 1. Pin Mode vs. SPI Mode Pin Changes

Pin

Pin Mode (SPI_EN = 0)

SPI Mode (SPI_EN = 1)

5

BYPASS

MOSI

6

MUTE

SCK

19

SCO_EN

SS

20

MISO

SPI mode provides the ability to configure two device pins as general purpose input/output (GPIO) pins. With

default register settings, pins 24 and 1 operate as RATE0 and RATE1. In SPI mode, these pins can be

configured as GPIOs (GPIO0 and GPIO1 respectively), but they do not explicitly change function to GPIOs upon

entering SPI mode by setting SPI_EN high. These pins will continue to operate as RATE0 and RATE1 until they

are optionally configured differently via SPI register writes. Once changed, these pins will continue to operate as

GPIOs even after reentering pin mode by setting SPI_EN low.

Serial Data Input

The LMH0366 input has a 100

Ω differential internal termination and supports a rail-to-rail input common mode

voltage for versatility in DC input coupling. It is intended to be DC coupled to devices such as the LMH0394

adaptive cable equalizer.

The input is equalized and includes signal detection with a programmable threshold, accessible via the SPI.

Input FR4 Equalization

The input includes an FR4 equalizer capable of equalizing up to 60” of FR4 trace.

The FR4 equalizer can be optimized for long trace lengths via the SPI. For input FR4 trace lengths longer than

40”, it is recommended to set register 0x11 bit 1 (EQ_BOOST_60) to enable additional equalizer boost in order

to compensate for the longer trace length.

Copyright © 2012–2013, Texas Instruments Incorporated

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