L86-M33 VCC decoupling capacitor and power supply filtering recommendation

Hello,

I am using the Quectel L86-M33 GNSS module in a rocket payload PCB. The module will be powered from a regulated 3.3 V rail. I am trying to design the VCC power supply filtering/decoupling properly.

My current plan for the L86-M33 VCC pin is:

  • 10 µF capacitor to GND

  • 100 nF capacitor to GND

  • Both capacitors placed close to the VCC/GND pins

I also have the option to add an additional 1 µF capacitor in parallel if needed.

My questions are:

  1. Is 10 µF + 100 nF sufficient for the L86-M33 VCC supply decoupling?

  2. Would adding an additional 1 µF capacitor improve stability against peak current transients, or is it unnecessary?

  3. Do you recommend using a ferrite bead or 0-ohm resistor between the main 3.3 V rail and the GNSS module VCC, followed by local capacitors?

  4. Are there any specific layout recommendations for the L86-M33 power supply pins, especially for applications with nearby switching regulators and RF modules?

The system also includes an STM32 microcontroller, MS5611 pressure sensor, and an E22 LoRa module, so I want to keep the GNSS power supply as clean and stable as possible.

Thank you.

Hi @Duffy

Please refer to the hardware design guidelines as below:

  1. Quectel_L80&L86&LC86L_Reference_Design_V1.3 | Quectel
  2. Quectel_L86_Hardware_Design_V1.3 | Quectel

For your questions, it is highly recommended to have the capacitor arrangement as such 10uF, 100nF and 33pF. Also add in TVS diode for protection. Plus, it also recommended to have a test point as well.

Best regards,