NEO-D9S - Integration manual
4.7.4.2 VCC pad
The VCC pad for the u-blox D9 correction data receiver needs to have as low an impedance as
possible with large vias to the lower power layer of the PCB. The VCC pad needs a large pad and the
decoupling capacitor must be placed as close as possible. This is shown in the figure below.
Figure 29: VCC pad
4.8 Design guidance
4.8.1 General considerations
Check power supply requirements and schematic:
• Is the power supply voltage within the specified range and noise-free?
• If USB is not used, connect the V_USB pin to ground.
• It is recommended to have a separate LDO for V_USB that is enabled by the module VCC. This is
to comply with the USB self-powered specification.
• If USB is used, is there a 1 uF capacitor right near the V_USB pin? This is just for the V_USB pin.
• Is there a 1 uF cap right next to the module VCC pin?
• Connect the power supply to VCC.
• Compare the peak current consumption of the NEO-D9S L-band module with the specification
of your power supply.
• L-band receivers require a stable power supply. Avoid series resistance (less than 0.2 Ω) in
your power supply line (the line to VCC) to minimize the voltage ripple on VCC. See the NEO-
D9S
section in the
chapter for more information on the power supply
requirements.
• All I/O (including UART) must not be pulled high before power ON.
• Any pull ups must be tied to module VCC to ensure they are at the correct state on power ON
and OFF.
• Allow all I/O to Float/High impedance (High-Z) when VCC is not applied.
4.8.2 RF front-end circuit options
It is mandatory that the RF input is fed by an active antenna meeting the requirements for
the NEO-D9S.
The first stages of the signal processing chain are crucial to the overall receiver performance.
When an RF input connector is employed this can provide a conduction path for harmful or
destructive electrical signals. If this is a likely factor the RF input should be protected accordingly.
Additional points on the RF input
• What is the expected quality of the signal source (antenna)?
UBX-19026111 - R07
4 Design
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