resistor details

[Vtrai]

my question is in STM32F407VGT6 , LPQF100, resistor R26,R27, R28 is N/A and 0..what does it mean exactly i.e.,one resistor R26 N/A is connected to VDD and another resistor R27,R28 is connected to VSS(99pin)..and second question is does VSS has a supply from VDD?..and what is N/A and what is '0' and what is the is use of those resistors?.. please help me to sort out this issue...

[Tesla DeLorean]

Sorry what BOARD or document are you looking at?

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Some F4 and F7 parts within family have slightly different pin configuration so resistor fitted or not fitted​ may support broader range of parts, ie 407, 411, 427, 466 etc

[Vtrai]

stm32f4discovery board

[Ozone]

> my question is in STM32F407VGT6 , LPQF100, resistor R26,R27, R28 is N/A and 0..

The STM32F407VGT6 has no R27 and R28.

I guess you mean the Discovery board.

The term "N/A" usually means "not applicable", i.e. the component is not placed on the PCB.

It wouldn't make much sense to connect a VSS pin of the MCU to VDD via a resistor, except for creating additional current consumption.

[Vtrai]

then what is the need of connecting those resistors in stm32f4 discovery board..and does VSS has a power supply now..which is usually connected to R27,R28

[waclawek.jan]

VSS means ground.

Pin 99 of STM32F407VG used to have a different meaning in the very distant past, see PDR_ON pin not available on LQFP100 package for revision Z devices erratum.

JW