TCAN1144-Q1: TCAN1144 Standby Mode

Karsten, this is unrelated to this question but relates to a question you asked in 2018 about a tacho IC for a Ford Capri! The thread was closed so there was no way of responding. The MIC/2 was a custom part number for Lucas who I believe made the cluster. The base part was a SN76810P if I am not mistaken. 

https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/728399/looking-for-information-about-mic2-c

I worked in internal sales during the 80s and we sold large volumes of these to several automotive customers. Probably not relevent any more but I like the chance to close a loose end.

David

Carsten,

What is the expected current from the transceiver? The SWE timer causes the device to go into Sleep mode once fully elapsed, so this is why the current would drop once 3-5 minutes have passed. 

Regards,

Eric Hackett 

Hi David, thanks for your reply. To be honest this was more a private topic as this device was part of cluster of a friend of mine...

BR Carsten

Hi Eric,

Actually the customer wants to understand the TCAN1144 more.

Therefore, they want to know any possibilities to put device to Sleep Mode without waiting 3-5 minutes or not.

They have some requirements about the current consumption and timing of sleep mode.

Could you provide the information about ?

• If and how would it be possible to go to Sleep Mode (Standby ) for TCAN1144 without waiting 3-5 minutes ?
• Is there any drawback/disadvantage if they change TCAN1144 from Normal Mode to Standby Mode without waiting 3-5 minutes (SWE timer) ?

 BR

Carsten

Carsten,

The TCAN1144-Q1 is configured and controlled through SPI. SPI commands can be used to transition the device between different states, including Sleep mode. And no, there is no drawback to transitioning the device between states using SPI. The SWE timer is meant to be a feature that helps in case the device gets stuck in a fault state and doesn't continue to drain the power supply (typically battery) by staying in Normal or Standby states. And to be clear, the SWE timer, once elapsed, places the device in Sleep mode, not Standby mode.

Regards,

Eric Hackett 

Hi Eric, I think there is some misunderstanding regarding the wording.

Customer wants to put the device into sleep mode without getting the SWE timer getting active.

This should be possible by writing MODE_SEL=001 to register 10h “Mode_CNTRL”

Correct?

BR

Carsten

Hi Carsten,

Carsten Koeck said:

This should be possible by writing MODE_SEL=001 to register 10h “Mode_CNTRL”

Yes, and VIO needs to be supplied to use SPI. 

Regards,

Sean

Team, customer is coming back with some more questions:

Thank you for your feedback.

Sorry for late response. I just back from vacation.

Actually, our software only transitions from normal mode to standby mode (not sleep mode).

Our sequences with below step:

Step No.1: After power on, TCAN will go to the standby mode.

Step No.2: Software changes the TCAN to Normal mode (by trigger command to the SPI -> MODE_CNTRL Register with MODE _SEL as 111b ).

Step No.3: During normal mode, if the no message on CAN bus -> the SWE timer start after t_Silence. (Refer below capture from TCAN’s user manual)

Step No.4: Software change the TCAN to Standby Mode.

My question:

• When SWE timer start in the Normal mode -> if Software trigger SPI command to transition from Normal to Standby Mode, is it stop/expired SWE timer here or it still running?
• If we clear the CANSLNT interrupt flag and transition to Standby Mode, is the SWE timer stop/expired?
• Will “Clear the CANSLNT” lead to any drawback/disadvantage ?

Thank you for your great support.

Sean,

regarding item #2:

"Cleared" mean that the SWE timer will stop and be skipped?

BR

Carsten