The LMH1297 is a 12G UHD-SDI 75-? bidirectional I/O with integrated reclocker. This device can be configured either as an adaptive cable equalizer or as a cable driver with integrated reclocker, supporting all SMPTE video rates up to 11.88 Gbps. The bidirectional I/O has an on-chip 75-? termination and return loss compensation network that provides ease of use and meets stringent SMPTE return loss requirements. The LMH1297 allows system designers the flexibility to use a single BNC either as an input or output port, simplifying UHD video hardware designs.

Equalizer mode (EQ mode): SDI_IO+ is configured as a 75-? adaptive cable equalizer. The input signal then goes through a reclocker, followed by a 100-? driver with de-emphasis at OUT0±. A second 75-? cable driver provides a reclocked loop-through output of SDI_IO+ at SDI_OUT+. This second signal path from SDI_IO+ to SDI_OUT+ forms a SDI cable loop-through.

Cable Driver mode (CD mode): SDI_IO+ is configured as a 75-? cable driver with a reclocked signal sourced from IN0±. SDI_OUT+ serves as a second 75-? cable driver to offer 1:2 fan-out buffering from IN0± to SDI_IO+ and SDI_OUT+. The 100-? driver at OUT0± can be used as a host-side loop-back output for monitoring purposes.

The on-chip reclocker attenuates high-frequency jitter and fully regenerates the data using a clean, low-jitter clock. The reclocker has a built-in loop filter and does not require any input reference clock. The LMH1297 also has an internal eye opening monitor and a programmable pin for CDR lock indication, input carrier detect, or hardware interrupts to support system diagnostics and board bring-up.

The LMH1297 is powered from a single 2.5-V supply with an on-chip 1.8-V LDO regulator. The operating state of the LMH1297 can be configured through control pins, SPI, or SMBus serial control interface. In the absence of an input signal, the LMH1297 automatically goes into Power Save mode. Users can also set the device into power-down operation through the ENABLE control pin. The LMH1297 is offered in a small 5-mm × 5-mm, 32-pin QFN package.