Both SBC families have 3 low-dropout regulators (LDOs): VCC1, VCC2, and VEXCC. In TCAN29xx-Q1, VCC1 will still be the main LDO that controls state transitions and SPI communications and can supply up to 250mA. However, VCC2 on TCAN29xx-Q1 is limited to 100mA and is not short-to-battery protected or -1V GND shift protected.

Design Consideration: Make sure the VCC2 loads of TCAN29xx-Q1 are not drawing more than 100mA and are not at risk of a short-to-battery or ground shift event. If they are, use VEXCC instead or add extra protection circuitry such as Zener diodes and reverse polarity protection diodes.

VEXCC in TCAN29xx-Q1 will have tighter Vshunt threshold for better current limiting capabilities. No design change is needed in this regard when switching over from TCAN28xx-Q1, but something to consider if you are wanting to potentially shrink the size of your PNP transistor since the current will be limited sooner.

Load sharing between VCC1 and VEXCC differs slightly between TCAN28xx-Q1 and TCAN29xx-Q1. In TCAN28xx-Q1, the current limit and current ratio between VCC1 and VEXCC is determined solely based off the Rshunt value between VSUP and VEXMON. However, when you are load sharing, the current limit is disabled on VEXCC. In TCAN29xx-Q1, the ratio is set by setting the VEXCC_VCC1_LOAD_RATIO register bit field to the desired ratio. This allows for current limiting in load sharing and standalone mode for VEXCC.

Design consideration: To share loading between VCC1 and VEXCC with TCAN29xx-Q1, be sure to set the ratio via a register write and adjust the value of Rshunt accordingly.