TCAN1043HG-Q1: Vsup Pin in TCAN1043HG- Q1

Akilan G14

Part Number: TCAN1043HG-Q1
Other Parts Discussed in Thread: TCAN1043, TCAN1043H-Q1

Hello Sir,

I am looking into Automotive CAN transceivers for our application, I came across TCAN1043HG-Q1, I am not sure why the Vsup is used for.

Thanks

Akilan G

over 6 years ago

0 Eric Hackett over 6 years ago

TI__Guru 64872 points

Akilan,

VSUP is meant to be the connection to car battery, it supplies the internal LDO that is the reference for the digital logic. The other two power inputs, VCC and VIO supply the CAN bus and the TXD and RXD levels, respectively.

Please let me know if you have any other questions.

Regards,

0 Akilan G over 6 years ago in reply to Eric Hackett

Intellectual 285 points

Hey Eric, Thanks for quick reply.

Okay. So, can the Vsup and Vio be an optional if necessary. Because I see in reference design, the Vsup is directly grounded.

And Also, Could you tell me about INH pin.

Akilan G

0 Eric Hackett over 6 years ago in reply to Akilan G

TI__Guru 64872 points

Akilan,

No, VSUP is not optional. Can you refer me to the reference design where VSUP is grounded?

INH is an output that is pulled up to VSUP and is meant to be used to supply another power supply on board (LDO or SMPS). It is disabled in Sleep mode, and enabled in Standby and Normal modes. The intent for the output is to supply an on board power supply IC that will provide power to the MCU controlling the TCAN1043. In sleep mode, which is a low power consumption mode, the INH pin is low, so the on board power supply is off, and thus the MCU is off. The TCAN1043 will then receive a wake up request through the bus and go into Standby mode. In Standby mode, the INH supply will come back up, and supply the LDO or SMPS providing power to the MCU, which will send a signal to the EN pin on the TCAN1043, and the device will be in Normal mode.

This isn't the only way to use the pin, but this is the typical and intended use in most low power applications. I made a lot of assumptions about your understanding of the device in that explanation, so if there is something you didn't quite understand, let me know and I will elaborate.

Regards,

0 Akilan G over 6 years ago in reply to Eric Hackett

Intellectual 285 points

Hey Eric,

The explanation is very helpful. I understand the INH Pin now.

I am attaching the png file of the circuit where the VSUP is grounded.

Akilan G

0 Eric Hackett over 6 years ago in reply to Akilan G

TI__Guru 64872 points

Akilan,

The schematic shows the VSUP net name on the pin with the decoupling capacitor, C5. If you look at the entire schematic, VSUP is most likely somewhere else, and that net name is referencing that point in the circuit, so you don't have to show the physical connection in the schematic and have wires crossing over each other unnecessarily.

Let me know if that makes sense.

Regards,

0 Akilan G over 6 years ago in reply to Eric Hackett

Intellectual 285 points

Makes sense. So, I can give 70 V on VSUP. Right ?

0 Eric Hackett over 6 years ago in reply to Akilan G

TI__Guru 64872 points

If you have the TCAN1043H-Q1 or the TCAN1043HG-Q1 versions of the device, yes, you can. But there will be little to no margin for any extended voltage spike. Will there be 70V on VSUP in the application?

Regards,