NXP Semiconductors AN13125, Примечание к применению

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NXP Semiconductors
AN13125
IW416 Design Guide
3 Clock source
Two main clock sources are available: a crystal, and an external oscillator. An optional
sleep clock is also available for low power mode.
3.1 Crystal
In a typical application, a 26 MHz or 40 MHz crystal is used as a reference clock source.
We recommend to select a crystal with ±10 ppm at 25°C and ±10 ppm over the operating
temperature range. For detailed crystal specifications, refer to IW416 data sheet.
Figure 7 shows the crystal connections. The internal capacitor in the Wireless SoC is
used to tune the crystal frequency. External loading capacitors are typically not needed.
Figure 7. Typical crystal circuit
PCB layout guidelines for the crystal
Refer to the following guidelines for the crystal:
• Place the crystal close to the device and keep it as far away as possible from the RF
side of the device and high frequency signal traces such as SDIO, PCIe, or USB.
• Keep XTAL_IN and XTAL_OUT traces far from any noisy or switching signal, at a
distance of at least ten times the substrate height.
AN13125 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2021. All rights reserved.
Application note Rev. 1 — 26 May 2021
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