S32K344 power supply

[DeenLiu]

I want the S32K344 uses an external BJT to control the generation of Core voltage, Is the voltage input to the BJT required to be equal to 5V or 3.3V? If I input 5V to VDD_HV_A and VDD_HV_B, and 5.8V to VC_BJT, will this cause the core voltage to be out of control? This BJT is similar to an LDO, I think it should be closed-loop control? The manual only mentions 5V and 3.3V, so not sure if other voltages are possible.

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[VaneB]

Hi @DeenLiu 

To ensure proper operation of the MCU, follow the recommendations provided in the Hardware Design Guidelines for S32K3xx Microcontrollers.

S32K3 MCUs for General Purpose – Hardware Design Package 

B.R. 

VaneB

[DeenLiu]

Hi @VaneB thanks for your reply.

My question is that FS26 series does not seem to be mass-produced yet. We want to find some alternatives, such as Infineon's TLF35584, which can provide a 5.8V voltage for the external transistor of V15. I wonder if it is feasible?

[petervlna]

Hello,

As I see from datahsheet:

A linear regulator can be implemented by connecting a bipolar NPN transistor from the VDD_HV_A or VDD_HV_B, supply voltage shown as VC_BJT

petervlna_0-1670485521805.png

next:

petervlna_1-1670485559309.png

So if you supply 5.8V to BJT from VDD_HVA or B then I see no issue here except limitation:

2. 6.0 V maximum for 10 hours over lifetime; 7.0 V maximum for 60 seconds over lifetime.

However if you use 2 separate supplies then I see violation of our recommendations.

Correctly you would use 5V to 5.5V for long time operation.

Best regards,

Peter