Table 12. USB recommendations (continued)
Checkbox Recommendation Explanation/Supplemental Recommendation
5. If using USB_OTG2, connect USB_OTG2_VBUS
via a resistive voltage divider to the VBUS pin of
the connector such that the 5.5 V VBUS voltage is
reduced to 3.3 V On QM (ball A35) and QXP (ball
H16).
On QM and QXP, the OTG1 and OTG2 interfaces are
implemented differently, and while the OTG1 VBUS ball
is 5 V tolerant, the OTG2 VBUS ball is not.
6. Route all USB differential signals with 90 Ω
differential impedance.
USB_OTG1 is not compatible with the SS interface.
7. ESD protection should be implemented at the
connector pins. Choose a low-capacitance device
recommended for high-speed interfaces.
This will prevent potential damage to board components
from ESD.
Table 13. HDMI recommendations (i.MX8 QM only)
Checkbox Recommendation Explanation/Supplemental Recommendation
1. Connect a 499 Ω, 1 % resistor to ground on
the HDMI_RX0_REXT ball (ball BJ11).
2. Connect a 499 Ω, 1 % resistor to ground on
the HDMI_TX0_REXT ball (ball BJ7).
3. Route all HDMI receive and transmit
differential pairs with 100 Ω differential
impedance.
4. To provide a Display Port output on the
i.MX8 QM Display TX output, follow the
implementation details in Figure 31.
5. To provide an HDMI output on the
i.MX8 QM Display TX output, follow the
implementation details in Figure 32.
6. The HDMI_TX0_CEC trace must be pulled
up to the VCC_3V3 rail through a 27 k Ω
resistor in series with a Schottky diode.
Table 14. Oscillator/crystal recommendations
Checkbox Recommendation Explanation/Supplemental Recommendation
1. Connect a 32.768 kHz crystal between
RTC_XTALI and RTC_XTALO.
For the ESR selection, the negative resistance/ESR and drive
level must be considered at the same time. See the processor
datasheet for the general crystal requirements. Follow the
manufacturer’s recommendation for loading capacitance.
Use short traces between the crystal and the processor
with a ground plane under the crystal, load capacitors, and
associated traces.
Internal load capacitors should be used. See Internal load
capacitor trimming (24 MHz and 32.768 kHz).
Table continues on the next page...
NXP Semiconductors
i.MX8 QM and QXP design checklist
i.MX8 QM / i.MX8 QXP Hardware Developer’s Guide, Rev. 2.4p, 06/2021
User's Guide 17 / 89
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