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taegyunahn
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Distributor - Changnam (South Korea)
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Hello

I have a question regarding ECO settings related to transitioning from Active mode to DeepSleep mode in CYT2B9.

I have seen the following statement in Figure 3. Active mode to DeepSleep mode transition of Infineon-AN220222_Low-power_mode_procedure_in_TRAVEO_T2G_family-ApplicationNotes-v06_00-EN

"If any FLL/PLL is used as operation clock with the ECO as its reference clock, change the clock to IMO"

m_s_v_0-1679474977665.png

 

Q1 : Is it not possible to transition to DeepSleep while in a state where ECO is set without switching to IMO?

Q2 : If Q1 is possible, is there a difference in power consumption between setting to IMO and setting to ECO?

 

Thank you.

MSV

 

 

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abhikul
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50 sign-ins 10 solutions authored 25 replies posted

Hello @taegyunahn 

  • The settling time for ECO clock is more as compared to IMO clock.
  • After a wakeup operation, at first IMO clock is enable and this clock is used as a reference clock at the initial stage. Once ECO clock is stable, then that clock is used as a reference clock. Please refer image1 which is taken from the application note itself.
  • IMO clock is enabled all the time so as to work all the functions properly. The CPU will automatically turned off this clock during deepsleep mode.
  • So, for any devices or peripherals that needs to be operated immediately after a deepsleep weakeup, IMO clock is use as a reference clock.

Thanks & Regards

Abhishek Kulkarni

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abhikul
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50 sign-ins 10 solutions authored 25 replies posted

Hello @taegyunahn 

  • ECO is External Crystal Oscillator which is a high frequency clock connected to the ECO_IN and ECO_OUT pins. This is an external clock provided to the CPU. Refer image1 for the description of ECO which is taken from the datasheet of the device.
  • In the same application note (AN220222) refer image 2 which states that all the high frequency clocks are shut down and all the I/Os (GPIOs) are frozen when transition from active to deepsleep mode.
  • As all the GPIOs are in the frozen state, the pins P21.2 (ECO_IN) and P21.3 (ECO_OUT) will be also be frozen which will shutdown the ECO clock output. Refer image3 which is taken from device datatsheet.
  • IMO is an internal main oscillator and a reference clock when no external reference clock is available or enabled. Refer image4 for description for IMO.
  • As all the high frequency clocks are off and GPIOs are frozen, so IMO clock is used as a reference clock when transition from active to deepsleep mode.

 

Thanks & Regards

Abhishek Kulkarni

taegyunahn
Level 4
Level 4
Distributor - Changnam (South Korea)
100 sign-ins 25 replies posted First comment on blog

Thank you for your answer.

You explained that IMO is used as the reference clock because high-frequency clocks (ECO) stop when switching from active mode to deep sleep mode, but there is something I don't understand.

As shown in the image below, in DeepSleep Mode, the state of the High-Speed clock (IMO/ECO/PLL) is confirmed to be off.

m_s_v_0-1679533061792.png

Looking at the image above, both IMO and ECO seem to be off in DeepSleep mode.

 

I am currently implementing a function to switch from Active mode to DeepSleep mode in Traveo II MCU, and I want to know if I must change to IMO when switching because I am using ECO as the reference clock.

Q1>  If it can be used as a reference clock even if it is turned off in deep sleep mode, can't ECO be used as a reference clock?

Q2 > Is it necessary to set IMO as the reference clock when switching from Active mode to DeepSleep mode?

 

Thank you.

MSV

 

 

 

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abhikul
Moderator
Moderator
Moderator
50 sign-ins 10 solutions authored 25 replies posted

Hello @taegyunahn 

  • The settling time for ECO clock is more as compared to IMO clock.
  • After a wakeup operation, at first IMO clock is enable and this clock is used as a reference clock at the initial stage. Once ECO clock is stable, then that clock is used as a reference clock. Please refer image1 which is taken from the application note itself.
  • IMO clock is enabled all the time so as to work all the functions properly. The CPU will automatically turned off this clock during deepsleep mode.
  • So, for any devices or peripherals that needs to be operated immediately after a deepsleep weakeup, IMO clock is use as a reference clock.

Thanks & Regards

Abhishek Kulkarni