I too have the same question, the datasheet seems to give insufficient information on this. Two things I did find:
1. "VREG_AVDD also powers the chip’s power-on reset and brownout detection blocks, so it must be powered even if the
on-chip voltage regulator is not used."
2. "With the exception of the two voltage regulator supplies (VREG_VIN and VREG_AVDD), which should be powered up together,
RP2350’s power supplies may be powered up or down in any order."
This means that VREG_AVDD definitely needs to be connected to 3v3. Is the RC filter needed if we won't be using the SMPS?
Also, 2) suggests that we need connect VREG_VIN to 3v3 even if we are not using the SMPS. This would activate the SMPS ("The regulator starts up in Normal mode when its input supplies are first applied"), and we can only set the regulator to high impedance mode once code is running.
This leaves the question of what to do with VREG_LX and VREG_FB, and also whether we really must supply VREG_VIN if the regulator is not being used (the datasheet suggests yes).
1. "VREG_AVDD also powers the chip’s power-on reset and brownout detection blocks, so it must be powered even if the
on-chip voltage regulator is not used."
2. "With the exception of the two voltage regulator supplies (VREG_VIN and VREG_AVDD), which should be powered up together,
RP2350’s power supplies may be powered up or down in any order."
This means that VREG_AVDD definitely needs to be connected to 3v3. Is the RC filter needed if we won't be using the SMPS?
Also, 2) suggests that we need connect VREG_VIN to 3v3 even if we are not using the SMPS. This would activate the SMPS ("The regulator starts up in Normal mode when its input supplies are first applied"), and we can only set the regulator to high impedance mode once code is running.
This leaves the question of what to do with VREG_LX and VREG_FB, and also whether we really must supply VREG_VIN if the regulator is not being used (the datasheet suggests yes).
Statistics: Posted by Transonic — Sun Sep 01, 2024 10:26 pm