Analog Devices Inc. 118100-HMC646LP2

Overview

HMC646LP2 from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC SPDT failsafe RF switch in a 2×2 mm DFN package, designed for T/R switching and LNA protection in high-power cellular and satellite infrastructure. It operates from 100–2100 MHz, delivers +46 dBm P0.1dB on Tx, exhibits 0.4 dB typical insertion loss, and maintains failsafe operation with Tx path enabled when unpowered - ideal for TD-SCDMA/3G repeaters and automotive telematics.

For engineers reviewing the HMC646LP2 datasheet, HMC646LP2 pinout, HMC646LP2 application, or HMC646LP2 equivalent, this page provides verified electrical specs, failsafe control behavior, thermal limits, frequency-band-specific performance data (915/1600/2015 MHz), and real-world evaluation PCB implementation guidance.

Technical Context

The HMC646LP2 implements a monolithic GaAs pHEMT-based SPDT architecture with integrated DC blocking on all RF ports (RFC, Tx, Rx) and a failsafe topology that defaults to RFC→Tx conduction at Vctl = 0 V. Its control logic accepts single positive voltage (0/+5 V typical) with ±0.2 V tolerance and supports Vdd from +3 V to +8 V.

Thermal design centers on a thermally enhanced exposed paddle requiring direct soldering to PCB RF ground; Tx and Rx channels share identical 14.75 °C/W thermal resistance and 4.4 W continuous dissipation limit. Absolute max ratings include +44 dBm CW input on Tx and +36.75 dBm on Rx, with operating temperature spanning −40°C to +85°C.

Key Specifications

Pinout & Package

Package: 2×2 mm, 6-pin leadless DFN with exposed thermal paddle (MSL1, Sn/Pb finish). Ground paddle must be soldered to PCB RF ground per Hittite land pattern guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SPDT RF switch applications.

Compared with QM11036 and SKY13370-374LF, the HMC646LP2 uniquely combines failsafe Tx-default operation, +46 dBm power handling, and validated 915/1600/2015 MHz band performance - making it irreplaceable in automotive telematics and 3G repeater designs demanding both robustness and band-specific linearity.

Availability

HMC646LP2 is available at Aetrix Electronics and suitable for TD-SCDMA infrastructure, satellite subscriber terminals, and automotive telematics requiring stable component supply, long-lifecycle support, and traceable GaAs MMIC sourcing.

Supply support for HMC646LP2 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 acquired Hittite Microwave in 2014 and maintains its high-frequency RF portfolio, specializing in GaAs, GaN, and SiGe MMICs for defense, communications, and instrumentation.

The HMC646LP2 belongs to Hittite's legacy SPDT switch product line, engineered specifically for high-power, failsafe T/R switching in cellular infrastructure and mission-critical wireless terminals.

FAQ

What is the absolute maximum CW input power rating for the HMC646LP2 Tx port?

The HMC646LP2 Tx port has an absolute maximum CW input power rating of +44.00 dBm, corresponding to approximately 25 W continuous RF power. This limit is defined at a channel temperature of 150 °C and assumes proper thermal management via the exposed paddle soldered to PCB ground. Exceeding this rating risks permanent device degradation.

Does the HMC646LP2 require external DC blocking capacitors on all RF ports?

Yes, the HMC646LP2 requires external DC blocking capacitors at RFC, Tx, and Rx ports, as explicitly stated in the truth table and application circuits. All three RF pins are DC-coupled internally, so external 1000 pF (915 MHz), 330 pF (1600/2015 MHz), or similarly rated capacitors must be placed in series to prevent DC path conflicts with connected components.

How does the failsafe operation of the HMC646LP2 behave when Vctl is unconnected or at 0 V?

When Vctl is at 0 V or left floating (unpowered), the HMC646LP2 defaults to RFC→Tx conduction - meaning the transmit path is active and RFC→Rx is isolated. This failsafe behavior is inherent to the GaAs pHEMT topology and requires no external components, making it essential for automotive eCall and emergency radio systems where power loss must preserve transmission capability.

What is the thermal resistance (θ_JA) of the HMC646LP2, and how is it achieved?

The HMC646LP2 has a thermal resistance of 14.75 °C/W for both Tx and Rx channels, measured from junction to ambient under standard JEDEC conditions. This value is achieved through the 2×2 mm DFN package's exposed copper paddle, which must be fully soldered to a dedicated PCB ground plane with multiple thermal vias - per Hittite's recommended land pattern - to realize specified power dissipation.

Which evaluation PCB corresponds to the HMC646LP2 configured for 2015 MHz operation?

The evaluation PCB number 118100 is designated for HMC646LP2 operation at 2015 MHz, as confirmed in the "Components for Selected Frequencies" table. This board uses specific matching components: C2 = 1.1 pF, C4 = 100 pF, C6 = 0.5 pF, C7 = 2.7 pF, L1 = 1.8 nH, L2 = 3.3 nH, and R1 = 10 kΩ - all optimized for 2010–2025 MHz band performance.