LMK1D1208IRHAR

Clock Buffers, Drivers Overview

The LMK1D1208IRHAR is an I2C-configurable, low-additive jitter LVDS clock buffer manufactured by Texas Instruments. It features two selectable inputs and eight differential LVDS output pairs (OUT0–OUT7) housed in a 6-mm × 6-mm, 40-pin VQFN package. The device supports supply voltages of 1.8 V, 2.5 V, or 3.3 V ± 5% and operates within an industrial temperature range of –40°C to +105°C. Key electrical specifications include a maximum output frequency of 2 GHz, additive jitter of less than 60 fs RMS (measured at 156.25 MHz with a 12 kHz to 20 MHz integration bandwidth), and a typical phase noise floor of -164 dBc/Hz. Propagation delay is maintained below 575 ps, with output skew limited to 20 ps maximum.

Clock Buffers, Drivers Feature Summary

• I2C programmability for individual input/output enable/disable, bank multiplexer selection, and output amplitude control (standard 350 mV or boosted 500 mV).
• Universal input compatibility accepting LVDS, LVPECL, HCSL, CML, and LVCMOS signals.
• Fail-safe input design with hysteresis to prevent random oscillation when no input signal is present.
• Four programmable I2C addresses determined by IDX0 and IDX1 pins.

Clock Buffers, Drivers Applications

• Telecommunications and networking equipment
• Medical imaging systems
• Test and measurement instrumentation
• Wireless communications infrastructure

Clock Buffers, Drivers Procurement Notes

Verify the ordering suffix 'RHAR' corresponds to the specific 40-pin VQFN package variant required for the design. Confirm that the I2C address configuration via IDX0 and IDX1 pins aligns with the system's bus topology. Ensure power supply decoupling meets the recommended operating conditions for the selected voltage rail (1.8 V, 2.5 V, or 3.3 V). Check thermal management requirements given the junction-to-ambient thermal resistance of 39.1 °C/W.

Clock Buffers, Drivers Selection Notes

Select the LMK1D1208IRHAR over pin-controlled variants (such as LMK1D1208P) when dynamic reconfiguration of output banks, individual channel enabling, or variable output swing is required during operation. This model is suitable for applications needing precise duty cycle control and low additive jitter (<60 fs RMS) compared to standard buffers. Consider the 40-pin package size if board space allows, as it offers more flexibility than the 28-pin LMK1D1208.

Clock Buffers, Drivers Part Context

The LMK1D1208I belongs to the LMK1D12xx family of low-additive jitter LVDS buffers. Unlike the standard LMK1D1208 which uses pin-controlled global output enable, this I-suffix variant provides granular control via I2C registers. It shares the same core performance metrics, such as the 2 GHz output frequency and <575 ps propagation delay, but distinguishes itself through software-defined configurability for complex clock distribution networks.

Clock Buffers, Drivers Replacement Considerations

LMK1D1208PRHAR: Pin-compatible alternative with identical package but controlled via hardware pins rather than I2C. LMK1D1208RHDT: Standard version with 28-pin VQFN package; requires schematic and layout redesign due to different pinout and package dimensions.