V15 Internally Regulator using NPN Ballast Circuit

[KarthikRaja]

Hi ,

We are using S32K312 dev board for development and planning to make a custom board (single board for s32k312 & s32k314) for our application using the EVB schematics. I could see V15 voltage domain where NPN Ballast circuit is given in the schematic. 

If I use the NPN Ballast circuit, should I need to give 1.5V from external source or if the jumper J31 setting 2-3= close is used will I be able to get 1.5V to V15.

Note : I am not using F26 circuit, Instead I am using a different voltage regulator.

[VaneB]

Hi @KarthikRaja 

When the jumper (J31) position is 1-2 the FS26_VCORE domain [+1.5V] is directly routed to the
V15_MCU domain. When is 2-3 the NPN external Ballast transistor is selected to supply the V15_MCU domain. And when is OPEN the V15_MCU domain is disconnected and isolated from the local external supplies.

The recommendations for the V15 (High-current logic supply voltage) are provided in section 2.7 of the Hardware Design Guidelines for S32K3 Microcontrollers, Rev. D4 (Hardware Design Package). Check this document, it might be useful for you. 

B.R.

VaneB

[KarthikRaja]

Hi Vane,

Thanks for your update.

To be clear, when I select Jumper 2-3 (close), then V15_MCU domain will get 1.5V from NPN ballast circuit itself by controlling through VRC_CTRL MCU PIN.  Is my understanding right?

[VaneB · Accepted solution]

Hi @KarthikRaja 

Yes, the passage of electric current will be carried out only between VDD_HV_NPN and V15, as long as VRC_CTRL acts.