Doubts related to SBC FS26 and SBC FS65 Power Supply Topology

[Nishant2]

Hello All,
I have gone through FS26 and FS65 power supply architecture. I have few doubts regarding the architecture.
FS26

1. It mentions TRKIN, LDOIN, COREIN pins voltage range between (0.3V to 8.5V max). It mentions intended to be connected to VPRE. Can we connect these pins with external power supply (different from FS26)?
2. If yes, can we connect TRKIN, LDOIN, COREIN pins to 12V external power supply?
3. Or if we connect TRKIN, LDOIN, COREIN pins with VPRE that is output of Buck, will the current capability of VPRE (which is 1.5A as mentioned) will reduce as TRKIN, LDOIN, COREIN pins will consume the current from the Buck?

FS65

1. In FS65 VPRE is internally connected to all other supplies. Will it reduce the supply current of PRE (which is 2A as mentioned) as FS65 internal circuit will also consume the current?

[TomasVaverka]

Hello Nishant,

FS26:

1. Yes, they can be connected to an external power supply, provided the voltage levels are within the absolute maximum ratings and recommended operating conditions.

2. No, connecting these pins directly to 12V would exceed the absolute maximum rating of 8.5V which could damage the device.

3. Yes, they will draw current from VPRE and this does reduce the available current budget from the 1.5A VPRE output.

FS65:

1. This 2.0A includes both internal and external loads. Internal blocks like VCORE (DC-DC), VCCA (LDO), VAUX (LDO) and CAN_5V (LDO) are all powered from VPRE. If your application requires external current from VPRE, you must subtract the internal consumption from the 2.0A budget.

BRs, Tomas