NXP Semiconductors MIMXRT1170HDUG Hardware Development Manual

• Clock and other high-speed traces must be as short as possible, it’s necessary to have a GND plane under these traces.• RXC and TXC are high-speed (125MHz) signals; Keep a 20mil space between clock and data signals.• Match each RGMII TX and RX (RXC/RXD/RXCTL/RXDV) group trace length to within +/-50mil.• Route the RGMII traces at 50ohm impedance, and make sure those traces are routed over an unbroken GND referenceground plane.• For the RXC signal from the PHY, place R/C close to the PHY (less than 500 mils) and adjust the R/C value to tune the timing.7.7 High-speed signal routing recommendationsThe following list provides recommendations for routing the traces for high-speed signals. Note that the propagation delay and theimpedance control must match to have a correct communication with the devices.• The high-speed signals (SDRAM, RMII, RGMII, USB, Display, Hyperflash, SD card) must not cross gaps in thereference plane.• Avoid creating slots, voids, and splits in the reference planes. Review the via voids to ensure that they do not create splits(space out vias).• Provide ground return vias within a 100-mil distance from the signal layer-transition vias when transitioning between differentreference ground planes.• A solid GND plane must be directly under the crystal-associated components, and traces.• The clocks or strobes that are on the same layer need at least 2.5× spacing from the adjacent traces (2.5× height from thereference plane) to reduce crosstalk.• All synchronous modules must have the bus length matching and relative clock length control.• For the SD module interfaces:— Match the data, clock, and CMD trace lengths (length delta depends on the bus rates).— Follow similar SDRAM rules for data, address, and control as for the SD module interfaces.• For the RT1170 FlexSPI module to support QSPI flash, FlexSPI_DQS pin should be kept floating to achieve high-speed access.7.8 Unused pins recommendationTable 12. Recommended connections for unused analog interfacesModule Ball Name Recommendations if Unused32 kHz OSC RTC_XTALI, RTC_XTALO Not connectedIt is recommended that RTC_XTALI ties to GND if external crystal isnot connected.ADC ADC_VREFH 10 kΩ resistor to groundVDDA_ADC_1P8 10 kΩ resistor to groundVDDA_ADC_3P3 10 kΩ resistor to groundCCM CLK1_N, CLK1_P Not connectedDAC DAC_OUT Not connectedMIPI VDD_MIPI_1P0 For lowest leakage, 10 kΩ resistor to ground. For possible easier layoutbut higher leakage, tie directly to power (inductors and capacitors areTable continues on the next page...NXP SemiconductorsLayout recommendationsHardware Development Guide for the MIMXRT1160/1170 Processor , Rev. 2, 09/2021User Guide 21 / 24

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