MC33772B enter slee mode

[shiqi_seventeen]

Hello team,

I am developing a BMS using the MC33772B and its sleep mode. During the development process, I have noticed that when there is no SPI communication with the MC33772B, it waits for 60 seconds to enter IDLE mode. Similarly, when I attempt to put the MC33772B into sleep mode using the appropriate method,

it also waits for 60 seconds before entering sleep mode.

My questions are:

1. Why does it need to wait for 60 seconds to enter sleep mode?

2. What should I do if I want it to  enter sleep mode without the delay?

Thank you for your assistance.

[JozefKozon]

Hello Shiqi,

it looks, that you have never left the INIT mode. While the 33772 is in idle mode, no messages are recognized, only a valid wake-up sequence lets the device transition from idle mode to INIT mode. Please refer to the section 9.3 "Modes of operation" in the MC33772B datasheet. To leave the INIT mode and enter the NORMAL mode, you need to set the new, non-zero CID (Cluster ID or Part address in the Figure 7.) to the MC33772B. In the event the device is powered up and not initialized, the 33772 enters the low-power idle mode after a tIDLE timeout period (60s). Please refer to the section 11.1.1 "Initialization register – INIT" for the new CID setting description.

With Best Regards,

Jozef

[shiqi_seventeen]

Thanks Jozef！
So if I enter the normal mode before going into sleep mode, do I not need to wait for 60 seconds to enter sleep mode, but instead enter it quickly?

[JozefKozon]

Hello Shiqi,

exactly. In the INIT mode, you cannot command the MC33772B to enter SLEEP mode. The MC33772B will enter IDLE mode after 60s if the CID was not changed=>entered NORMAL mode. From normal mode, the MC33772 may be commanded to sleep mode. Please refer to the section 9.3.1 "Normal mode". 

With Best Regards,

Jozef

[shiqi_seventeen · Accepted solution]

However, since I am able to normally collect voltage and current parameters through "on-demand acquisition," I believe I am currently in the normal mode. Then, by writing 1 to SYS_GLOBAL[SLEEP], I enter the sleep mode.But it is clearly not successful.

[JozefKozon]

Hello Shiqi,

please share your schematic with voltage levels and part values. Or are you using our EVB (Evaluation Board)? Yes, if the on demand measurement works, then you are in Normal mode (or Diagnostic mode). The on demand measurement is not available in the INIT mode. Please refer to the Table 8. Just to confirm. Haven't you mistaken the "on-demand acquisition," with cyclic measurement? The cyclic measurement is available in both Normal mode and Sleep mode. So your transition to Sleep mode might be successful and you are still reading the voltage and current values.

Please confirm that you have changed the CID value to non-zero. 

How many Cells have you connected to the MC33772B?

With Best Regards,

Jozef