In Vehicle Networking中的主题 Re: TJA144

TJA144

chothesnehal — Wed, 05 Nov 2025 05:27:56 GMT

Hello NXP team,

We are using TJA1445A CAN IC in our design. Could you please confirm on supply to Vbat. In datasheet Vbat range is 4.75V to 40V , VCC is 4.25V to 4.75V . Can we use same 5V to Vbat and VCC?

Re: TJA144

TomasVaverka — Wed, 05 Nov 2025 08:06:24 GMT

Hello Snehal,

Based on the datasheet:
- VBAT (battery supply): 4.75V to 40V
- VCC (CAN transmitter supply): 4.5V to 5.5V
- VBAT undervoltage detection: 4.25V to 4.75V
- VCC undervoltage detection: 4.0V to 4.5V

So yes, you can use the same 5V supply for both VBAT and VCC, provided:
- The 5V supply is stable and meets the minimum VBAT requirement (> 4.75V).
- You set VBATVCC = 1 in the System configuration register to indicate common supply usage.
- Ensure the regulator can handle the current for both VBAT and VCC loads.

BRs, Tomas

Re: TJA144

chothesnehal — Wed, 05 Nov 2025 09:11:16 GMT

In 5V to VCC and VBAT , we will not be able to turn off 5V ? as mentioned in this image. one more query:if we give Vbat 24V will work? is there any limitation from current consumption perspective?

Re: TJA144

TomasVaverka — Wed, 05 Nov 2025 13:22:20 GMT

Hello Snehal,

The note says: “When VCC is expected to be turned off in a low-power mode, VBAT must be higher than 5.5 V for proper CAN bias generation.” This means the device expects VBAT to remain active when VCC is off, so if both are tied to the same 5V rail, you lose that flexibility. If you need low power modes (Sleep/Standby), you should keep VBAT separate from VCC. If low power mode is not critical, using a common 5V supply is acceptable.

Yes, VBAT range is 4.75V to 40V, so 24V is within spec. Current drawn from VBAT is very low as shown in Table 1 of the datasheet. Even at 24 V, the current remains in the microamp range, so power dissipation is negligible. The main current consumption comes from VCC (CAN transmitter), which is 6–60mA depending on mode. So, no major limitation for VBAT at 24V except ensuring proper filtering and transient protection.

BRs, Tomas

Re: TJA144

chothesnehal — Wed, 05 Nov 2025 12:30:48 GMT

Hello Tomas,

Thank you for clarification.

Regards,

Snehal