launchpadxl-f28377s Vref

Hi,

Iker Bilbao said:

I would like to know if it is possible to use a external Vref supply (HI;LO), at which pins and range values.

These details are very well given in the datasheet Section 4.1 Signal Descriptions

Iker Bilbao said:

I can not find out at the different LaunchpadXL pin map docs or even in the LaunchDemo applications supplied.

You can find the Launchpad schematics here: C:\ti\controlSUITE\development_kits\LAUNCHXL-F28377S\HwDevPkg

Demo code: C:\ti\controlSUITE\development_kits\LAUNCHXL-F28377S\LaunchPadDemo

Peripheral Example codes: C:\ti\controlSUITE\device_support\F2837xS\v191\F2837xS_examples_Cpu1

Regards,

Gautam

I assume the datasheet Section 4.1 Signal Descriptions is about F28377S and not the LaunchpadXL I am working on.
In the LaunchpadXL suggested schematic (sheet 3/6) Vrerhi and Vreflo are opamp outputs, so I understand these are values I can not modify in the LaunchPadXL so I will not find in the pinmap.

Hi Iker,

On the F2837xS device family, VREFLO must always be 0V, so you won't be able to source this externally (on the launchpad it is directly connected to ground).

As for the VREFHI voltage, if you want to use a different voltage you could replace the REF3030 IC with a different IC (for example, REF 3025 to get 2.5V). If you want to force a specific VREFHI voltage from an instrument, you could remove the REF3030 and then solder a wire to the pad that was connected to pin 2 (the reference's voltage output). You could also remove the op-amps and then force the reference voltage directly on the pin, but this is not preferred.

Thanks, that helps me a lot.
I would work with the TMS320F28377S device on a new dedicated board before messing with the LaunchPadXL (so usefull to learn).