PCA9450 can not be configured in SNVS mode

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PCA9450 can not be configured in SNVS mode

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wenqiuzhang
Contributor I

Hi sir,

We want to change the output voltage and power on sequence of PCA9450 before the it steps into RUN mode.

When 5V(VSYS) power on, and PCA9450 step into SNVS mode, we use I2C to config the related register, and PCA9450 didn't response with any errors, and we also read this register which configured, it wasn't been changed.

However we pull-up the PMIC_ON_REQ, the PMIC steps into RUN mode, then, change the value of the output voltage, it works.

Is is normal?

By the way, if we do not use the CLK_32K_OUT, is that means the PCA9450 not need the external 32.768KHz crystal?

Thanks a lot!

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ErikaC
NXP TechSupport
NXP TechSupport

Hello, 

Thank you for your patience, It seems that it is not possible to modify those registers until the POR_B pin is in high state, (the POR_B pin is the pin that goes high when the power up sequence is finished) so it is not possible to modify the voltages before the power up sequence.

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ErikaC
NXP TechSupport
NXP TechSupport

Hello,

Regarding your first question, let me check with the applications team, are you using the PCA9450 EVB?

If you do not use the CLK_32K_OUT, does that mean the PCA9450 does not need the external 32.768KHz crystal? Yes, it does not need the external crystal. . If external 32.768 kHz crystal oscillator is not populated, CLK_32K_OUT pin outputs 32 kHz clock from internal 32 kHz oscillator.

Hope this helps.

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