Resistive Pull Up

[Anonymous]

Hi,

   

How  much is the resistance of the internall pull-up of a PSoC5LP?.

   

Currently I have a PSoC5LP connected to 20 SPI Slave devices with 20 separate chip select lines (digital output, resistive pull up).

   

Since the pins are connected to Vdd, I would like to know how nuch is the current draws, and if I need an external pullup resistor

[Anonymous]

 GPIO pullup/pulldown  resistor - min 3.5k, typ.5.6k max 8.5k

[Bob_Marlowe]

It is nowhere recommended to use the internal pullups for I2C. In all drawings there are always external pullups shown. Even the pioneer board uses external pullups.

       

Bob

[Anonymous]

@HL thanks

   

@Bob, but that for I2C not SPI, right?

[Bob_Marlowe]

Sorry, that was for I2C only. Mis-red

       

Bob

[ETRO_SSN583]

Not relevant to SPI but you can use internal pullups for I2C depending

   

on buss loading and speed. From NXP (Phillips) specs -

       

[ETRO_SSN583]

The spec (I2C)  for those interested -

           

          http://www.nxp.com/documents/user_manual/UM10204.pdf

       

Regards, Dana.

[Anonymous]

It is convenient to use the internal resistor, but if power consumption is your concern, external resistor is the way to go, just make sure the leakage current would not change the voltage level.

[Anonymous]

Power consumption not really a problem, but space are.

[Anonymous]

How about some 01005 resistor. (0.4mm x 0.2mm)
 

[Anonymous]

They already have a smaller one

   

008004 size (0.25 x 0.125 mm) !!!!!

[Anonymous]

that is smalllll..wonder how P&P machine handle those tiny packages.