SimpleLink crystal-less wireless MCUs make it easy to go crystal-free

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Innovation in the semiconductor industry often involves improving upon existing products, but when it comes to design, less is more. At Texas Instruments, we looked at the electronic build of materials (BOM) around our SimpleLink crystal-less wireless MCUs and wanted to remove the external high-frequency crystal without sacrificing any features or functionality. This is where our revolutionary bulk acoustic wave (BAW) resonator technology comes into play.

Whether you are designing a building security system with space constraints or a power tool to operate in a harsh physical environment, BAW resonator technology can be used.

We integrated the BAW resonator into a multiprotocol 2.4-GHz MCU, resulting in the CC2652RB, a crystal-less wireless MCU device that supports communication via Bluetooth low energy, ZigBee, and Thread protocols, and is available in a 7 mm x 7 mm quad flat no-lead (QFN) package.

How does it work?
The CC2652RB is a variant of our CC2652 family of devices. It integrates a BAW resonator chip inside the package, as shown in Figure 1. This BAW chip generates the high-speed 48MHz clock signal that an external quartz crystal would normally generate, thereby removing the external crystal from the board.

Figure 1: Silicon-based BAW technology

What are the advantages of BAW?
Save PCB space
In applications such as wearable medical devices, saving space is critical. The CC2652RB is designed for space-constrained wireless applications. Removing the external 48MHz crystal reduces the footprint of a traditional 7mm x 7mm QFN wireless MCU by 12%. This also increases the flexibility of routing sensors and peripherals to GPIO pins.

Simplify development
Quartz crystals are one of the most common pain points in radio frequency (RF) layout. They are often the source of problems such as noise, crosstalk or crystal frequency tuning. During the product development phase, a new PCB revision is often required to solve these problems. This increases development costs. Using CC2652RB can avoid these risks.

Robustness and Durability
Many of today’s innovative products are used in harsh environments. From the constant vibration of industrial robots to the mechanical shock of dropped devices, wireless devices need to operate reliably in many situations.

BAW resonator technology is a design choice for long-term operation in harsh environments. In testing to industry standard MIL-SD-883H, it is more resilient to mechanical shock and vibration environments, and its frequency accuracy variation is three times lower than that of an external quartz crystal. The device is also rated for a lifetime of up to 10 years, while quartz crystals are typically 5 to 6 years. This means higher wireless frequency stability and fewer timing and transmission errors with nearly double the lifespan.

Quartz crystals are also more susceptible to cracking under mechanical shock, terminating the device’s wireless functionality. If the external crystal shatters, it will need to be completely replaced to restore wireless functionality. With BAW resonators, you no longer need a quartz crystal as a fragile component in your application.

Physical Security
Utilizing BAW resonator technology reduces potential weaknesses in MCU security. Removing the external crystal reduces the chances of side-channel attacks related to system timing.

I currently use CC2652R,

How do I migrate to the CC2652RB?
Migrating from the CC2652R to the CC2652RB is very simple. The two devices are pin compatible in the 7 mm x 7 mm QFN package. Since the devices use the same silicon inside the package, connecting to a 48-MHz external crystal is as simple as you did originally, without connecting pins.

From a software perspective, the change is very simple: you only need to change the clock source register. With the common SimpleLink Platform Software Development Kit (SDK) used by all SimpleLink devices, the rest of your software can be seamlessly transitioned to the CC2652RB

Designing with the CC2652RB is very simple. You will find that migrating from the CC2652R to the CC2652RB reduces the overall footprint and simplifies the design process.

How do I get started with BAW?
Step 1: Purchase the LP-CC2652RB LaunchPad development kit.
Step 2: Download the CC13x2-CC26X2 SDK.
Step 3: Complete the out-of-box experience and take SimpleLink Academy training.

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CC2652RB SimpleLink 无晶振 BAW 多协议 2.4GHz 无线 MCU (1).pdf (1.65 MB, downloads: 2)