Microchip Ruggedizes Evacuated Miniature Crystal Oscillators

Microchip Know-how not too long ago introduced the EX-423 evacuated miniature crystal oscillator (EMXO), a timing system that delivers high-frequency stability with minimal energy and house necessities. The corporate created the EX-423 as an addition to its EX-421 timing system portfolio for battery-powered and harsh environments.

The EX-423 is designed for battery functions, ocean backside nodes, navy moveable radios, satellite tv for pc communications, and extra. Picture used courtesy of Microchip

With mechanical ruggedization and a decrease steady-state energy profile, the EX-423 is appropriate to be used in GNSS monitoring techniques, navy moveable radios, and airborne tools.

An Evacuated Miniature Crystal Oscillator

Microchip designed the EX-423 (datasheet linked) to make use of much less house and energy with out compromising on options. The system is available in a 15.2 mm x 15.2 mm package deal and attracts 0.20 W at 3.3 V in regular state, whereas delivering a frequency vary of 10 MHz to twenty MHz and accepting both 3.3 V or 5.0 V enter energy. 

The corporate additionally added many options to the EX-423 to ruggedize it for harsh environments. For instance, Microchip included a four-point crystal mount that distributes pressure throughout the crystal clean. The unfold stresses functionally cut back g-sensitivity to lower than 1 ppb/g per axis and qualifying shock survivability to 1,000 g per MIL-STD-202 Methodology 213 Situation E. 

Typical part noise of the EX-423. Picture used courtesy of Microchip

In the meantime, frequency stability over temperature is rated at ±5 ppb from 0°C to +50°C, ±10 ppb from −20°C to +70°C, and ±20 ppb from -40°C to +85°C, overlaying the complete navy working vary. The EX-423 additionally encompasses a vibration endurance of 15 g peak and 15 g RMS from 10 Hz to 2000 Hz.

Most of the remaining options Microchip applied within the EX-423 enhance its compatibility for designers. To help interfacing with digital logic and RF sign chains, the corporate permits designers to configure the EX-423’s RF output as CMOS or sinewave.  

Vacuum Thermal Insulation and Crystal Mounting in Oscillators

An EMXO oscillator is a tool that achieves frequency stability by utilizing a vacuum as a passive thermal barrier. With no fuel molecules to conduct warmth between the crystal and its enclosure, the crystal temperature adjustments extra slowly as ambient circumstances shift. 

This structure additionally has energy advantages. Specifically, an EMXO makes use of much less steady-state energy than an oven-controlled crystal oscillator (OCXO), which runs an lively heater to carry the crystal at a set temperature setpoint. Since this mechanism usually requires 1–2 W or extra in regular state, it’s not best for battery-powered designs, making EMXOs the de facto favourite.

G-sensitivity measurement utilizing the tipover take a look at. Picture used courtesy of Microwave Journal

EMXOs also can exhibit improved frequency stability when designers make use of intelligent mounting constructions. When a crystal oscillator experiences vibration or mechanical shock, the ensuing acceleration forces act on the crystal clean, shifting its resonant frequency. In field-deployed techniques akin to navy radios or seismic nodes, this frequency shift might degrade the timing reference for so long as the vibration persists, compromising navigation accuracy, communication synchronization, or knowledge integrity. 

Subsequently, a crystal’s mounting construction can considerably affect the oscillator’s sensitivity to exterior forces, often known as g-sensitivity. Distributing mounting, for instance, lowers the oscillator’s g-sensitivity as a result of it makes use of extra attachment factors to scale back internet pressure on the crystal for a given shock amplitude.

Availability

The EX-423 is now accessible in SMD and through-hole configurations. The system is RoHS 6-compliant, with an elective Sn63/Pb37 solder coating.