EVA-8M and EVA-M8 series - Hardware Integration Manual
UBX-16010593 - R06
Design-in
Page 11 of 47
Early Production Information
Name
Component Function
Comments
U1
LDO
Regulates VBUS (4.4 …5.25
V) down to a voltage of 3.3 V).
Almost no current requirement (~1 mA) if the GNSS receiver is
operated as a USB self-powered device, but if bus-powered LDO (U1)
must be able to deliver the maximum current of ~100 mA.
C24,C23 Capacitors
Required according to the specification of LDO U1
D2
Protection
diodes
Protect circuit from
overvoltage / ESD when
connecting.
Use low capacitance ESD protection such as ST Microelectronics
USBLC6-2.
R4, R5
Serial
termination
resistors
Establish a full-speed driver
impedance of 28…44
Ω
A value of 27
Ω
is recommended.
R11
Resistor
Ensures defined signal at
VDD_USB when VBUS is not
connected / powered
100 k
Ω
is recommended for USB self-powered setup. For bus-powered
setup R8 is not required.
Table 2: Summary of USB external components
See Appendix A.5 and Appendix A.6 for reference schematics for self- and bus-powered operation.
☞
If the USB interface is not used, connect
VDD_USB
to GND.
2.2.5
SQI Flash memory
An external SQI (Serial Quad Interface) Flash memory can be connected to the EVA-8M / EVA-M8
series GNSS modules. The SQI interface provides the following options:
•
Store the current configuration permanently
•
Save data logging results
•
Hold AssistNow Offline and AssistNow Autonomous data
☞
In addition, the EVA-M8M and EVA-M8Q GNSS modules can make use of a dedicated flash
firmware with an external SQI Flash memory. The flash memory with these modules can be used
to run firmware out of flash and to update the firmware as well. Running the firmware from the
SQI Flash requires a minimum SQI Flash size of 8 Mbit.
☞
The voltage level of the SQI interface follows the
VCC_IO
level. Therefore, the SQI Flash must be
supplied with the same voltage as
VCC_IO
of the EVA-8M / EVA-M8 module. It is recommended to
place a decoupling capacitor (C4) close to the supply pin of the SQI Flash.
☞
Make sure that the SQI Flash supply range matches the voltage supplied at
VCC_IO
.
Figure 3
: Connecting an external SQI Flash memory
