Analog Devices Inc. HMC856LC5TR

Overview

HMC856LC5TR from Analog Devices is a 5-bit digital time delay IC designed for high-speed timing compensation and clock skew management in serial data paths. It delivers 28 Gbps data rate support, 3 ps delay resolution, 92 ps maximum programmable delay range, and programmable differential output voltage swing from 500 mV p-p to 1350 mV p-p - enabling precise signal alignment in SONET OC-192 and CDR systems.

For engineers reviewing the HMC856LC5TR datasheet, HMC856LC5TR pinout, HMC856LC5TR application, or HMC856LC5TR equivalent, this device serves as a wideband, single-supply (−3.3 V) CML time delay with on-chip 50 Ω input/output termination, VR-controlled output level tuning, and monotonic delay stability across −40°C to +85°C.

Technical Context

The HMC856LC5TR implements a 5-bit digitally controlled delay line using current-mode logic (CML) architecture, with all inputs and outputs internally terminated to ground via 50 Ω (data paths) or 600 Ω (control lines). Its propagation delay ranges from 255 ps to 347 ps depending on digital setting and temperature, with <±12 ps variation over temperature and <2 ps deterministic jitter at 28 Gbps.

Delay programming is performed via five differential CML control pairs (B0± to B4±), while output amplitude is independently adjusted via the VR pin (−1.2 V to +0.4 V), directly modulating differential swing without altering delay resolution or monotonicity. The exposed paddle must be connected to VEE (−3.3 V) for thermal and electrical integrity.

Key Specifications

Pinout & Package

Package: 32-terminal ceramic leadless chip carrier (LCC), 5 mm × 5 mm, HE-32-1 footprint, exposed paddle tied to VEE.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital time delay applications.

Compared with HMC987LP5E and LMK04832, the HMC856LC5TR delivers optimal trade-off of 28 Gbps bandwidth, 3 ps resolution, single −3.3 V operation, and minimal 5 mm × 5 mm footprint - making it ideal for dedicated, low-jitter timing compensation where integration or ultra-fine resolution is not required.

Availability

HMC856LC5TR is available at Aetrix Electronics and suitable for SONET OC-192 infrastructure, high-speed test equipment, and clock and data recovery systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for HMC856LC5TR 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

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving communications, industrial, automotive, and aerospace markets.

The HMC856LC5TR belongs to Analog Devices' Hittite Microwave product line of RF and high-speed timing ICs, engineered specifically for broadband microwave and serial data applications demanding ultra-low jitter and precise delay control.

FAQ

What is the absolute propagation delay range of the HMC856LC5TR?

The HMC856LC5TR exhibits an absolute propagation delay from 255 ps (minimum, at 00000 control setting) to 347 ps (maximum, at 11111 setting) at 25°C. This 92 ps total range is monotonic and stable across temperature, with ±12 ps variation from −40°C to +85°C - confirmed in Figure 20 and Table 1 of the Rev. D datasheet. The HMC856LC5TR's delay is fully characterized and guaranteed within these bounds under specified operating conditions.

Does the HMC856LC5TR require external termination resistors for its CML I/O?

No, the HMC856LC5TR does not require external termination resistors for its differential I/O. Its I+ and I− inputs feature on-chip 50 Ω terminations to GND, and O+ and O− outputs are source-terminated to 50 Ω. As stated in the General Description and Interface Schematics (Figures 5 and 7), the HMC856LC5TR is designed for direct connection to 50 Ω-terminated systems - eliminating external resistors and minimizing parasitics critical at 28 Gbps.

How does the VR pin affect power consumption and rise/fall time in the HMC856LC5TR?

The VR pin on the HMC856LC5TR directly controls both output swing and power draw: increasing VR from 0 V to +0.4 V raises differential output swing from 500 mV p-p to 1350 mV p-p but increases supply current from ~185 mA to ~200 mA at 25°C (Figure 10). Simultaneously, rise/fall times increase from 20/18 ps to ~24/22 ps (Figure 14). These trade-offs are documented in Figures 10, 12, and 14 - meaning the HMC856LC5TR allows system-level optimization of amplitude, power, and edge speed.

Is the HMC856LC5TR pin-compatible with earlier revisions like HMC856LC5?

Yes, the HMC856LC5TR is pin-compatible and functionally identical to the base HMC856LC5 variant. Both share the same HE-32-1 ceramic LCC package, identical pinout (32-terminal), electrical specifications, and thermal design. The "TR" suffix denotes tape-and-reel packaging for automated assembly - confirmed in the Ordering Guide (Page 13) where HMC856LC5 and HMC856LC5TR share identical package description and option code HE-32-1.

What is the recommended PCB layout practice for the exposed paddle of the HMC856LC5TR?

The exposed paddle of the HMC856LC5TR must be soldered and electrically connected to the −3.3 V (VEE) net - not to GND - as explicitly required in the Pin Configuration section (Note 3) and Applications Information (Page 11). Multiple thermal vias (≥6, 0.3 mm diameter) should connect the paddle to an internal VEE plane, and the top-side paddle pad must be fully soldered per IPC-7093 guidelines. This ensures proper thermal dissipation (θJC = 30°C/W) and stable CML biasing, as verified in the Evaluation Board schematic (Figure 25).