Texas Instruments LMH0046MHX

Overview

LMH0046MHX from Texas Instruments is an HD/SD SDI reclocker IC that retimes serial digital video data at 143 Mbps, 270 Mbps, 1.483 Gbps, and 1.485 Gbps to suppress accumulated jitter in broadcast video signal chains. It features two differential LVPECL-compatible outputs, automatic rate detection, and a selectable second output for either reclocked data or low-jitter data-rate clock. It is used in digital video routers, format converters, and DVB-ASI equipment.

For engineers reviewing the LMH0046MHX datasheet, LMH0046MHX pinout, LMH0046MHX application, or LMH0046MHX equivalent, key selection considerations include SMPTE 292M/259M compliance, dual-output flexibility (data vs. clock), 20-pin HTSSOP package thermal performance, and 3.3V single-supply operation with 330 mW typical power consumption.

Technical Context

The LMH0046MHX implements a PLL-based reclocking architecture with auto-detecting loop bandwidth (300 kHz at 270 Mbps, 2.0 MHz at 1485 Mbps) and supports both fixed-rate and auto-rate modes via RATE[1:0] inputs. Its CML/LVPECL-compatible serial I/O interfaces directly with SMPTE-compliant equalizers (e.g., LMH0034) and cable drivers (e.g., LMH0002).

Control logic is LVCMOS-compatible, with dedicated pins for lock detect (LOCK DET), SD/HD rate indication, output mute (OP MUTE), bypass enable (BP/AUTO-BP), and SCO_EN for output mode selection. The device uses a 27 MHz ±50 ppm crystal or external reference and includes internal loop filter connections (LF1, LF2) for PLL stability tuning.

Key Specifications

Pinout & Package

LMH0046MHX is housed in a 20-pin HTSSOP (PWP) package with an exposed die attach pad (DAP) electrically connected to VEE (ground). The DAP must be soldered to a ground plane for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SDI reclocking applications.

Compared with LMH0046MHX, LMH0344RTVT offers higher data rate support but sacrifices dual-output versatility and auto-detection, while GS2971AIBE3 adds intelligence and diagnostics at the cost of increased BOM complexity and power supply requirements.

Availability

LMH0046MHX is available at Aetrix Electronics and suitable for digital video routers, broadcast format converters, DVB-ASI transmitters, and professional editing systems requiring stable component supply across long product lifecycles.

Supply support for LMH0046MHX includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies for industrial, automotive, and communications markets.

The LMH0046MHX belongs to TI's high-speed video interface product line, designed specifically for SMPTE-compliant broadcast infrastructure where signal integrity, jitter suppression, and standard interoperability are critical.

FAQ

What video standards does the LMH0046MHX support?

The LMH0046MHX supports SMPTE 259M (A & C) for SD-SDI at 143 Mbps and 270 Mbps, and SMPTE 292M (A & C) for HD-SDI at 1.483 Gbps and 1.485 Gbps. It also supports DVB-ASI operation at 270 Mbps. The LMH0046MHX does not support 3G-SDI, 6G-SDI, or HDMI protocols, and explicitly avoids locking to unsupported harmonics such as 177 Mbps or 360 Mbps.

How does the LMH0046MHX handle clock generation and output selection?

The LMH0046MHX recovers the serial data-rate clock internally and provides it as a low-jitter differential output via pins 13–14 (SCO/SDO2) when SCO_EN is high. When SCO_EN is low, those same pins deliver a second reclocked data stream. The LMH0046MHX does not generate clocks independently - it derives all timing from the incoming SDI signal and the 27 MHz reference, ensuring phase coherence with source video timing.

Can the LMH0046MHX operate without an external crystal?

No - the LMH0046MHX requires a 27 MHz ±50 ppm parallel-resonant crystal connected between pins 10 (XTAL IN/EXT CLK) and 11 (XTAL OUT), or a 27 MHz LVCMOS-compatible external clock applied to pin 10. The device contains no internal oscillator; omission of this reference prevents PLL lock and disables reclocking functionality. The LMH0046MHX will enter bypass mode if the reference is missing or out-of-tolerance.

What is the function of the SD/HD pin (pin 19) on the LMH0046MHX?

Pin 19 (SD/HD) is a registered logic output indicating the currently locked data rate: high = SD rates (143/270 Mbps), low = HD rates (1483/1485 Mbps). It is only valid when LOCK DET (pin 12) is high; otherwise, it defaults to low (HD). The LMH0046MHX uses this signal to coordinate with companion devices like the LMH0002 cable driver, enabling dynamic gain or equalization adjustment based on video format.

Does the LMH0046MHX support AC-coupled input and output interfaces?

Yes - the LMH0046MHX serial inputs (pins 5–6) and outputs (pins 13–14, 16–17) are fully compatible with AC-coupled 75 Ω coaxial interfaces. For AC-coupled inputs, an external bias network must be provided; for outputs, the internal 50 Ω pull-ups allow direct drive into 100 Ω differentially terminated loads, which can be adapted to 75 Ω systems using standard impedance-matching networks. The LMH0046MHX datasheet specifies 800 mV_P-P differential swing into 100 Ω, matching SMPTE-292M requirements.