User's Manual l MBa8x UM 0100 l © 2021, TQ-Systems GmbH
Page 33
TQMa8x
Mini PCIe
External
PCIe ref.
clock
M.2 PCIe
Figure 19:
Clock supply PCIe
All PCIe-CLK lines are routed with a differential impedance of 100 Ω. The clock line to the processor is not terminated to ground
with 49.9 Ω as required in i.MX8 QM/i.MX8 QXP Hardware Developers Guide. The termination is already included in the clock IC.
A quartz with a load capacitance of 8 pF is used. No capacitors are provided in series in the clock lines. A placement option is
provided on all OE pins, which allows the clocks to be switched off.
The reference input of the processor is connected to DIF0. The pull-up for switching off the clock remains unpopulated. The
reference input of the Mini PCIe slot is connected to DIF1.
DIF1 is activated by switching on V_3V3_MPCIE. DIF2 is connected to the reference input of the M.2 slot and is continuously
active. A placement option to switch off the output is not provided.
DIF3 is not connected.
3.14.13
SATA M.2
An M.2 socket with "B" coding is used for connecting a SATA SSD. In addition, mounting options are available for the 2242 and
2280 form factors.
The differential signals are elongated and have a differential impedance of 85 Ω. 10 nF coupling capacitors are placed in the data
lines. According to the M.2 specification, a maximum of 2.5 A is provided.
3.14.14
SIM
A SIM card holder (X12) is provided for the use of a GSM card.
TQMa8x
SIM-Card
SIM_RST
SIM_CLK
SIM_IO
SIM_PD
SIM_PWR_EN
1.8 or 3.3 V
Load
Switch
ESD
&
EMV
Figure 20:
Block diagram SIM card
3.14.15
USB hosts/hubs
The TQMa8x provides two USB OTG interfaces, of which USB OTG2 also supports USB 3.0. Due to specific limitations of the i.MX 8
USB controllers, only USB OTG2 can be used as interface for a USB hub. To provide four host interfaces, the TUSB8041 USB hub is
used. The hub has one upstream and four downstream ports.