Texas Instruments LMH1218RTWT

Overview

LMH1218RTWT from Texas Instruments is a low-power ultra HD cable driver with integrated reclocker, supporting serial video data rates up to 11.88 Gbps for SMPTE ST-2082/2081 (proposed), 424M, 344M, 292M, 259M, DVB-ASI, and 10GbE SMPTE 2022-5/6. It features dual differential inputs (IN0±, IN1±), dual outputs (75-Ω OUT0± and 100-Ω OUT1±), reference-free CDR lock, and SPI/SMBus programmability. Used in UHDTV routing and optical module interfaces.

For engineers reviewing the LMH1218RTWT datasheet, LMH1218RTWT pinout, LMH1218RTWT application, or LMH1218RTWT equivalent, this page delivers verified electrical specs (e.g., 300-mW power, 45-ps rise time at 11.88 Gbps), package mapping (24-pin WQFN, 4 mm × 4 mm), validated pin functions (e.g., LOCK as CDR lock indicator, ENABLE for power-down control), and confirmed alternatives for SMPTE/10GbE reclocking applications.

Technical Context

The LMH1218RTWT integrates a wide-range clock-and-data recovery (CDR) circuit capable of locking to data rates from 270 Mbps to 11.88 Gbps without external reference clocks or loop filters. Its dual-input 2:1 mux selects between two video sources, while on-chip equalization compensates for PCB trace loss up to 35 inches FR4.

It supports simultaneous 1:2 fanout via independent 75-Ω (OUT0±) and 100-Ω (OUT1±) outputs, each with programmable voltage swing and de-emphasis. The CDR latency is 1.5 UI + 195 ps for reclocked data and 230 ps in raw (bypass) mode, with deterministic jitter under 7 ps_P-P at 10.3125 Gbps on OUT1.

Key Specifications

Pinout & Package

LMH1218RTWT is housed in a 24-pin WQFN package (RTW suffix), 4.00 mm × 4.00 mm body size, with exposed thermal pad (DAP) requiring ≥5 vias to GND per TI package drawing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMH1218RTWT, LMH1228RTWT offers expanded input flexibility at higher power and cost, while THS8200IPHP serves fundamentally different analog-domain applications - neither is pin-compatible, and both require PCB redesign and firmware adaptation.

Availability

LMH1218RTWT is available at Aetrix Electronics and suitable for UHDTV routing, optical module interfacing, and DVB-ASI distribution amplifiers requiring stable component supply across broadcast, professional AV, and industrial video infrastructure programs.

Supply support for LMH1218RTWT 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 high-speed interface solutions for industrial, automotive, and communications markets.

The LMH1218RTWT belongs to TI's high-speed serial video interface product line, engineered specifically for SMPTE-compliant reclocking and cable driving in broadcast-grade UHDTV infrastructure.

FAQ

What data rates does the LMH1218RTWT support, and how is rate detection handled?

The LMH1218RTWT supports 11.88 Gbps (ST-2082), 10.3125 Gbps (10GbE), 5.94 Gbps (ST-2081), 2.97 Gbps (SMPTE 424M), 1.485 Gbps (292M), 270 Mbps (259M), and DVB-ASI. Rate detection is fully automatic: its wide-range CDR locks without external reference clocks, using internal algorithms to identify and adapt to incoming data rates within <5 ms. This is confirmed in Section 6.5 and Figure 7-1 of the SNLS474E datasheet.

Does the LMH1218RTWT require an external reference clock for CDR operation?

No, the LMH1218RTWT operates reference-free - it performs autonomous clock-and-data recovery across all supported rates (270 Mbps to 11.88 Gbps) without any external clock or loop filter components. This eliminates timing circuitry overhead and reduces board area, as explicitly stated in the "Features" section and Section 7.3 of the SNLS474E datasheet.

What is the function of the MODE_SEL pin on the LMH1218RTWT?

The MODE_SEL pin on the LMH1218RTWT is a 4-level strap input that selects the device's control interface: 1 kΩ to VDD configures SPI mode (using MOSI/MISO/SCK/SS_N), while 1 kΩ to GND configures SMBus mode (using SDA/SCL). Its state is latched at power-up and determines register map access and address assignment, as detailed in Table 5-1 and Section 5 of SNLS474E.

Can the LMH1218RTWT drive both coaxial and optical interfaces simultaneously?

Yes - the LMH1218RTWT supports simultaneous 1:2 fanout: OUT0± provides 75-Ω CML-compatible output for coaxial SMPTE links, while OUT1± delivers 100-Ω differential output compliant with SFF-8431 (SFP+) for optical modules. Both outputs operate concurrently with independent voltage swing and equalization settings, per Section 3 and Figure 8-2 of SNLS474E.

What thermal considerations apply to the LMH1218RTWT in continuous operation?

The LMH1218RTWT has a junction-to-board thermal resistance (RθJB) of 11.8°C/W and requires proper thermal management: the exposed DAP must be connected to GND with ≥5 vias, and PCB copper area should follow TI's WQFN layout guidelines. At 300 mW dissipation, ambient temperature must remain ≤85°C to keep junction temperature within spec, as specified in Section 6.4 of SNLS474E.