RT1176 internal DCDC performance

[VictorienV]

Hi NXP support engineer,

I'm working on a custom board with an RT1176 MCU and i'm looking for detailed characteristics about internal DCDC perfomance. I found on datasheet max output current and stability at fixed load (but unknown current).

Please could you share information about load transient response ?

[VictorienV]

Hi Diego,

thanks for your answer.

Our application is an industrial product with high PCB density and cost constraints. Than using an external PMIC isn't a good solution for us.

I made some tests of RT1170 DCDC with transient load condition and amplitude of overshoot/undershoot is very high (see below with a 0.05 to 0.25 A transient load).

RT1170 datasheet recommends a voltage between 1.0 to 1.15V for VDD_SOC_IN ; I interpret table 13 of the datasheet as consumption average values. I fear about CORE power supply stability during CORE computing load or change of operating mode.

[VictorienV]

Hi Diego,

Do you have more information regarding transient performance of RT1170 DCDC ?

[diego_charles]

@VictorienV 

I am very sorry for the delayed response!

At this moment I do not have more characterization  for the DCDC  to share, specifically about the  transient response.

According to the reference manual (IMXRT1170RM) "The on-chip DCDC converter is suitable for consumer and industrial applications up to the rated temperature specified in their respective market datasheets"

But,  you can share more details about your measurement. For example:  DCDC running mode (CCM, DCM, low power) ,  core operationg frequency, temperature. 

According to RM, DCDC improves transient response if running on DCM mode. See below snapshot from the RM. Section 21.6.2 Recommended configuration.

Best regards, 

Diego

[VictorienV]

Thanks for this answer.

I made my measurement with a POR state on RT1170 and didn't check register configuration or try to optimize the configuration.

I have to analyze that and update my measurement to confirm that register setting improve transcient performance.

[diego_charles]

Hi @VictorienV 

Thank you for your reply and bring the attention to this topic. Ok, please feel free to share  if you are still repeating the measurement. 

All the best, 

Diego

[diego_charles]

Hi @VictorienV 

Thank you for reaching out !  I do not have this characterization available, but could you let me know more about your application requirements and why we could help with that additional information ? Lets see what we can do!

As a little note, If the application is for automotive grade, it is better to use an external PMIC instead the on-chip  DCDC. See this snapshot from AN13213 

Regarding the current , we could see this data by checking the DCDC_IN rail specs on the DS. If we pick i.MX RT1170 Crossover Processors Data Sheet for Consumer Products we can find the MAX current , and typical current for this DCDC input rail. Below an snapshot. 

Thank you for your interest!

Diego