Analog Devices Inc. HMC856LC5

Overview

HMC856LC5 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 control range, and programmable differential output voltage swing from 500 mV p-p to 1350 mV p-p using a single −3.3 V supply. It is deployed in SONET OC-192 systems and broadband test equipment where precise sub-100 ps delay tuning is required.

For engineers reviewing the HMC856LC5 datasheet, HMC856LC5 pinout, HMC856LC5 application, or HMC856LC5 equivalent, key selection criteria include CML-compatible 28 Gbps operation, on-chip 50 Ω input/output termination, temperature-stable monotonic delay, VR-controlled output amplitude, and LCC package thermal performance at −40°C to +85°C.

Technical Context

The HMC856LC5 implements a fully monotonic 5-bit digital delay architecture with 3 ps step resolution and total propagation delay ranging from 255 ps to 347 ps. Its CML interface uses on-die 50 Ω terminations for I+/I− and O+/O−, and 600 Ω terminations for B4±–B0± control inputs referenced to positive supply ground.

Delay stability is maintained across temperature (±9 ps variation at +85°C, ±8 ps at −40°C) and supply voltage (±3 ps over −3.7 V to −2.9 V), enabled by internal compensation. The VR pin adjusts differential output swing while simultaneously affecting rise/fall time (20/18 ps typical) and power consumption (185 mA typical at −3.3 V).

Key Specifications

Pinout & Package

Package: 5 mm × 5 mm, 32-terminal ceramic leadless chip carrier (LCC), HE-32-1, with exposed paddle connected to VEE (−3.3 V). RoHS-compliant, MSL3 rated.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC856LC5, HMC987LP5E offers finer delay granularity and higher bandwidth but demands full schematic and layout rework, while LMK04832 provides integrated clock conditioning at the cost of resolution, speed, and interface compatibility-neither serves as a pin- or function-compatible replacement.

Availability

HMC856LC5 is available at Aetrix Electronics and suitable for SONET OC-192 infrastructure, high-speed serial test equipment, and broadband instrumentation requiring stable component supply with guaranteed long-term availability and MSL3 handling compliance.

Supply support for HMC856LC5 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 is a global leader in high-performance analog, mixed-signal, and RF ICs, serving precision instrumentation, communications, and industrial markets since 1965.

The HMC856LC5 belongs to Analog Devices' Hittite Microwave product line, engineered specifically for microwave and millimeter-wave timing, delay, and signal conditioning in test, defense, and optical transport systems.

FAQ

What is the absolute maximum delay range achievable with the HMC856LC5?

The HMC856LC5 provides a total delay control range of 92 ps with 3 ps resolution across its 5-bit control word (0–31 steps). The minimum propagation delay is 255 ps, and maximum is 347 ps at 25°C. Temperature variation adds ±9 ps at +85°C and ±8 ps at −40°C, all verified per Rev. D datasheet Table 1 and Figure 20. This range is fixed for the HMC856LC5 and cannot be extended beyond the specified 5-bit encoding.

Can the HMC856LC5 operate with a positive supply voltage?

No, the HMC856LC5 requires a single negative supply of −3.3 V (operating range −3.7 V to −2.9 V) applied to VEE pins and the exposed paddle. Its CML circuitry is designed for negative-rail operation with inputs and outputs referenced to ground. Applying a positive supply violates Absolute Maximum Ratings (Table 2) and will cause permanent damage. The HMC856LC5 does not support dual-supply or positive-supply configurations.

How is the VR pin used to adjust output voltage swing in the HMC856LC5?

The VR pin on the HMC856LC5 accepts an analog voltage from −1.2 V to +0.4 V to scale the differential output swing between 500 mV p-p and 1350 mV p-p. At VR = 0 V, output is typically 1130 mV p-p; increasing VR raises swing but also increases rise/fall time and current draw (e.g., 4.25 mA at VR = 0.4 V). VR must be driven by a low-noise, stable voltage source-direct connection to GND via JP1 is recommended for nominal operation per Figure 25 and Applications Information section.

Is the HMC856LC5 pin-compatible with other devices in the HMC856 family?

Yes, all HMC856 variants-including HMC856LC5, HMC856LC5TR, and HMC856LC5TR-R5-share identical pinout, package (HE-32-1 LCC), and electrical interface per Ordering Guide and Pin Configuration (Figure 3). Differences are limited to packaging format (tape-and-reel vs. cut tape) and quantity (R5 = 500-piece reel); no functional or pinout variation exists between these ordering options of the HMC856LC5.

What is the role of the VB pin on the HMC856LC5, and how must it be connected?

The VB pin on the HMC856LC5 is a DC bias reference terminal that must be connected directly to ground (GND) to establish correct internal operating points for the CML core and VR regulation circuitry. Leaving VB floating or connecting it to any other potential violates the Interface Schematics (Figure 8) and General Description, causing undefined output behavior and potential device malfunction. This requirement is explicitly stated in Table 3 and Figure 25 of the HMC856LC5 datasheet Rev. D.