Parts selection problem of 3.3V LDO

tomojitakasu / PocketSDR

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Parts selection problem of 3.3V LDO #3

Open tomojitakasu opened 2 years ago

tomojitakasu commented 2 years ago

The part for U5 (3.3V LDO) in HW/pocket_sdr_v.2.1.xlsx is not suitable. The output voltage of the LDO may be 5V instead of 3.3V by the current circuit design.

Replace the part for U5 by the proper one, in which the pin 4 of SOT-23-5 package shall be NC (no connection).

osqzss commented 2 years ago

The V_FB pin (pin 4) of RP111N331D-TR-FE has to be connected to the V_OUT pin (pin 5). You can use a 0603 (1608) 0-ohm SMD resistor as a quick fix. PXL_20220624_045804991

oberstet commented 6 months ago

The LDO seems to be replaced for v2.2, it now is:

LDO 3.3V 500mA SOT23-5 Nisshinbo RP111N331D-TR-FE

whereas the v2.1 used (or at least, the BOM list says):

LDO 3.3V 500mA SOT23-5 RICOH RP111N331D-TR-FE

tomojitakasu commented 6 months ago

RP111N331D-TR-FE is still not suitable, in which pin 4 is not NC. Replace it by another one with pin 4 as NC if using the original PCB design. It will be fixed in the next release.

https://www.digikey.jp/ja/products/detail/nisshinbo-micro-devices-inc/RP111N331D-TR-FE/10244938