Analog Devices Inc. HMC857LC5TR

Overview

HMC857LC5TR from Hittite Microwave Corporation is a 2×2 CML crosspoint switch IC designed for ultra-high-speed serial data routing in optical and high-frequency digital systems. It supports up to 14 Gbps data rates and 14 GHz selector operation, features programmable differential output swing (475–1200 mV_p-p), 21 ps rise/fall times, and operates from a single −3.3 V supply - enabling use in 10 GbE and 16G Fibre Channel line cards.

For engineers reviewing the HMC857LC5TR datasheet, HMC857LC5TR pinout, HMC857LC5TR application, or HMC857LC5TR equivalent, key selection criteria include its CML-compatible differential I/O architecture, on-chip 50 Ω termination, VR-controlled output amplitude tuning, and −40 °C to +85 °C industrial temperature range with ROHS-compliant ceramic SMT packaging.

Technical Context

The HMC857LC5TR implements a fully differential CML-based 2×2 switching matrix with independent select control of two differential input pairs (IN0, IN1) to two differential output ports (OUTA, OUTB). Its internal architecture includes on-die 50 Ω terminations referenced to Vee and integrated level-shifting logic for robust signal integrity at multi-GHz frequencies.

It uses a negative supply rail (−3.3 V) referenced to ground, with all inputs and outputs compliant to CML voltage levels (e.g., −510 mV low, −10 mV high). The VR pin enables real-time adjustment of output differential amplitude across process/temperature/voltage corners without external components.

Key Specifications

Pinout & Package

Package: 32-lead ceramic LCC (5 × 5 mm, 25 mm²), ROHS-compliant, with exposed paddle requiring solder connection to Vee. Alumina body with gold-over-nickel plating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed CML crosspoint switch applications.

Compared with HMC857LC5TR, HMC857LP5E trades SMT density and 14 GHz performance for easier hand-soldering, while LMH2190IRGET offers lower jitter at reduced data rate and fixed output level - making HMC857LC5TR optimal for amplitude-adaptive, high-density 14 Gbps routing where VR control and leadless packaging are essential.

Availability

HMC857LC5TR is available at Aetrix Electronics and suitable for SONET OC-192 line cards, 10GbE switch fabrics, and 16G Fibre Channel storage arrays requiring stable component supply across extended product lifecycles.

Supply support for HMC857LC5TR 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

Hittite Microwave Corporation was a U.S.-based RF/microwave semiconductor company specializing in high-frequency analog and mixed-signal ICs before its acquisition by Analog Devices in 2014. Known for performance leadership in millimeter-wave and high-speed logic.

The HMC857LC5TR belongs to Hittite's High-Speed Logic family, engineered specifically for CML-based serial data switching in telecom, datacom, and test instrumentation - emphasizing low jitter, wide bandwidth, and robust signal integrity at 10+ Gbps.

FAQ

What is the recommended power supply configuration for HMC857LC5TR?

HMC857LC5TR requires a clean, well-decoupled −3.3 V supply referenced to ground. Use ≥4.7 µF tantalum and 330 pF ceramic capacitors near Vee pins (27, 30) and the exposed paddle. The paddle and Vee pins must be soldered directly to the −3.3 V plane; insufficient grounding causes increased jitter and degraded return loss. Do not share this rail with noisy digital supplies.

How does the VR pin affect HMC857LC5TR output performance?

The VR pin on HMC857LC5TR sets differential output amplitude from 475 mV_p-p to 1200 mV_p-p by applying −1.2 V to +0.4 V. At VR = 0 V, typical output is 1000 mV_p-p. This allows dynamic compensation for channel loss or receiver sensitivity mismatch without redesigning the PCB layout. VR voltage must be stable and low-noise to avoid injecting jitter into the output waveform.

Can HMC857LC5TR accept single-ended inputs?

HMC857LC5TR is optimized for differential CML signaling but can accept single-ended inputs if AC-coupled and biased to mid-supply (−1.65 V) using an external resistor divider. However, common-mode noise rejection and jitter performance degrade significantly versus true differential drive. For best results, use differential CML sources or add a dedicated single-ended-to-differential converter upstream of HMC857LC5TR.

What is the maximum operating frequency of the select control inputs on HMC857LC5TR?

The select control inputs (SelA±, SelB±) on HMC857LC5TR operate up to 14 GHz, matching the data path bandwidth. This enables dynamic reconfiguration at multi-GHz rates - for example, toggling between input sources within a single 10 GbE packet boundary. Ensure select signals are routed as controlled-impedance differential pairs (50 Ω each to ground) with matched length to maintain timing integrity.

Is HMC857LC5TR pin-compatible with other Hittite crosspoint switches?

HMC857LC5TR is not pin-compatible with earlier Hittite crosspoints like HMC855LP5E or HMC856LC5TR due to differences in pin assignment (e.g., VR location, N/C pin count, ground distribution). Its 32-lead 5×5 mm LCC footprint is unique to this generation. Migration requires PCB layout revision; refer to the official Hittite pinout diagram (v02.0111) for exact terminal mapping before board design.