cancel
Showing results for 
Search instead for 
Did you mean: 

PCB design question of Bluenrg-LPS (Bluenrg-332ac)

JasonYang
Associate II

Hi everyone,

I am currently working on a PCB design using a Bluenrg-332ac chip. The official PCB design guideline has a resistor marked "X" as shown on the left of the figure below. But I saw the resistor soldered on the eval board. Can anyone explain whether we keep the resistor or not in the PCB design?

Reference files: AN5526  STEVAL-IDB012V1 

JasonYang_0-1710044982182.png

JasonYang_1-1710045176303.jpg

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
Laurent LOUAZON
ST Employee

Hello,

This resistor should not be there.
BlueNRG gives you flexibility to use or not internal SMPS. It is a matter of power consumption versus BOM saving .

If using SMPS, then R1 must not be set
If SMPS is not used, then R1 must be set and L1/L2 are not used.

Regards
Laurent

View solution in original post

3 REPLIES 3
Laurent LOUAZON
ST Employee

Hello,

This resistor should not be there.
BlueNRG gives you flexibility to use or not internal SMPS. It is a matter of power consumption versus BOM saving .

If using SMPS, then R1 must not be set
If SMPS is not used, then R1 must be set and L1/L2 are not used.

Regards
Laurent

Hi Laurent,

Thank you for your reply! I also want to ask if we remove R1 here, do we still need to connect the VBLUE to the circuit?

Regards,

Jason

Laurent LOUAZON
ST Employee

Hello Jason,

 

If you do not set R1 , it means you will use internal SMPS (so you will have L1 and L2 set).
SMPS must be activated by SW (CONFIG_HW_SMPS_10uH)

Then Vblue is used to supply other Vdd pins of the BlueNRG-LPS (VDDSD, VDDRF, VDD1 and VDD2)

 

Laurent