Texas Instruments LMH0026MHX

Overview

LMH0026MHX from Texas Instruments is a dedicated SD-SDI reclocker IC that retimes 270 Mbps serial digital video data per SMPTE 259M-C, suppresses accumulated jitter, and delivers two differential LVPECL-compatible outputs - one fixed data output (SDO) and one configurable output (SCO/SDO2) selectable as either second retimed data or low-jitter 270 MHz clock. It operates from a single 3.3 V supply, consumes 330 mW typical, and targets digital video routing and DVB-ASI equipment.

For engineers reviewing the LMH0026MHX datasheet, LMH0026MHX pinout, LMH0026MHX application, or LMH0026MHX equivalent, key selection criteria include its 270 Mbps SMPTE 259M-C compliance, dual-differential output flexibility, 0.02–0.08 UI_P-P output jitter performance, 20-pin HTSSOP package with exposed DAP, and LVCMOS control interface with lock detect and SD indicator outputs.

Technical Context

The LMH0026MHX implements a PLL-based reclocking architecture with a 27 MHz crystal or external reference input, loop filter pins (LF1/LF2) supporting a fixed 56 nF capacitor, and automatic or manual bypass modes. Its VCO/PLL recovers the 270 Mbps data-rate clock and re-times incoming CML/LVPECL-compatible SDI signals to produce low-jitter outputs.

Control logic includes SCO_EN (selects SCO/SDO2 function), OUTPUT MUTE (LVCMOS-active-low muting), BYPASS/AUTO BYPASS (LVCMOS-active-high forced bypass or auto-unlock bypass), LOCK DETECT (LVCMOS-active-high PLL lock status), and SD (LVCMOS-active-high 270 Mbps detection). All serial I/Os are differential, 100 Ω-terminated compatible, and support DC or AC coupling.

Key Specifications

Pinout & Package

LMH0026MHX is housed in a thermally enhanced 20-pin HTSSOP (PWP) package with an exposed die attach pad (DAP) electrically connected to VEE (ground); DAP must be soldered to a ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMH0026MHX, LMH0046MHX extends functionality to HD-SDI at higher power and cost, while LMH0346RTVT reduces external components and improves jitter but changes package and supply flexibility - LMH0026MHX remains the most balanced choice for dedicated, cost-optimized SD-SDI reclocking.

Availability

LMH0026MHX is available at Aetrix Electronics and suitable for digital video routers, DVB-ASI transport equipment, and broadcast editing systems requiring stable component supply, long-term lifecycle assurance, and SMPTE-compliant signal integrity.

Supply support for LMH0026MHX 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, with decades of leadership in broadcast video interface solutions.

The LMH0026MHX belongs to TI's LMH video interface product line, engineered specifically for SMPTE-compliant serial digital video signal conditioning - emphasizing jitter suppression, differential signaling integrity, and seamless integration with TI's ecosystem of equalizers and cable drivers.

FAQ

What is the primary function of the LMH0026MHX in an SDI signal chain?

The LMH0026MHX functions as a dedicated SD-SDI reclocker that retimes 270 Mbps serial digital video data per SMPTE 259M-C to suppress accumulated jitter. It recovers the data-rate clock, provides two differential LVPECL-compatible outputs (one fixed, one configurable), and includes lock detection and SD-rate indication - all within a single 20-pin HTSSOP package. The LMH0026MHX is not a serializer/deserializer or equalizer; it operates strictly as a jitter-cleaning repeater stage.

Can the LMH0026MHX operate without an external crystal?

No - the LMH0026MHX requires a 27 MHz timing reference applied to the XTAL IN/EXT CLK pin. This may be either a parallel-resonant 27 MHz crystal (with 20 pF load capacitance and ≤40 Ω series resistance) connected across XTAL IN/EXT CLK and XTAL OUT, or a 27 MHz LVCMOS-compatible clock signal driven directly into XTAL IN/EXT CLK. The device lacks an internal oscillator and cannot function without this reference.

How does the SCO_EN pin affect the behavior of the LMH0026MHX?

The SCO_EN pin determines the function of the SCO/SDO2 differential output pair: when SCO_EN is low (default, due to internal pulldown), SCO/SDO2 delivers a second retimed serial data output; when SCO_EN is high, SCO/SDO2 delivers a low-jitter 270 MHz serial data-rate clock. This selection is independent of OUTPUT MUTE and BYPASS/AUTO BYPASS states, though SCO/SDO2 is muted when OUTPUT MUTE is low or when bypass is active in clock mode.

What is the significance of the exposed DAP on the LMH0026MHX package?

The exposed die attach pad (DAP) on the LMH0026MHX is electrically connected to VEE (ground) and serves as the primary thermal and electrical return path. It must be soldered to a solid PCB ground plane to ensure proper thermal dissipation (θ_JA = 26.6°C/W) and stable operation at 330 mW. Leaving the DAP unconnected or floating violates the absolute maximum ratings and risks thermal shutdown or functional instability.

Does the LMH0026MHX support DVB-ASI operation, and how does it differ from SMPTE 259M-C use?

Yes - the LMH0026MHX supports DVB-ASI at 270 Mbps using the same 270 Mbps data path, PLL, and output structure as SMPTE 259M-C. No configuration change is needed; the device treats both standards identically since they share identical data rate, encoding (8B/10B not used), and electrical characteristics. The LMH0026MHX does not decode or interpret ASI packet content - it purely retimes the raw serial bitstream.