Is PMIC_ON_REQ controlled by firmware? Or it is raised high after providing of NVCC_SRTC only as response of i.mx536

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Is PMIC_ON_REQ controlled by firmware? Or it is raised high after providing of NVCC_SRTC only as response of i.mx536

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akshaybanknal
Contributor I

Hi,

I would like to know behavior of PMIC_ON_REQ pin (ball:W14) on I.mx536. When this pin will raise to high to indicate that all power supplies provided to i.mx536 are ok? Is this pin behavior is software controlled or..it is mere indication of NVCC_SRTC rail is high.

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igorpadykov
NXP Employee
NXP Employee

Hi Akshay

you can consider it as just "indication of NVCC_SRTC rail is high".

It is an output signal generated by SRTC timer, located in ALWAYS ON domain.

It allows (in systems, equipped with an Always On low power supply- coin cell

or similar) to do the following:

- Pre-program SRTC timer to some interval ;

- Put system to SRTC mode (all system but SRTC is OFF) ;

- Wake up and boot system upon time expiration.

SRTC generates short active low pulse at PMIC_ON_REQ output when timer expired.

Best regards

chip

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akshaybanknal
Contributor I

Hi,

First of all, thanks for your prompt reply.

You gave me good answer; but still I have some queries; that I have mentioned below:

We are using following Part in our project:

->MCIMX536AVV8C

We are referring to following document for Hardware Design:

->i.MX53 System Development User’s Guide (Version Details: MX53UG Rev. 1 3/2011)

1. We have connected PMIC_ON_REQ (ball:W14) to PWR_ON (Pin:20) of PMIC LTC3589HUJ-1.

2. We are facing problem with PMIC_ON_REQ: This pin never turns high to drive PWR_ON.

3. So currently we are driving PWR_ON pin by external source.

4. We have tested and identified that PMIC_ON_REQ never turns high even if all power domains of i.mx536 are high & having recommended voltages & also i.mx536 is working fine.

So we would like to know...& with reference to your previous reply;

1. Should we write anything in firmware / bootloader to drive this pin high?

2. Should we do any settings to SRTC timer to drive this pin high?

Regards,

Akshay Banknal.

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igorpadykov
NXP Employee
NXP Employee

Hi Akshay

LTC3589 PWR_ON should not be used with i.MX53 as noted in SCH-26751 p.5

(i.MX53 Sabre AI schematic).

General information about the PMIC_ON_REQ :

it is an output signal generated by timer, located in ALWAYS ON domain.

It enables (in systems, equipped with an Always On low power supply- coin cell

or similar) to do the following:

- Pre-program SRTC timer to some interval ;

- Put system to SRTC mode (all system but SRTC is OFF) ;

- Wake up and boot system upon time expiration.

SRTC generates short active low pulse at PMIC_ON_REQ output when timer expired,

signal should be connected to the PMICs ON input.

Also it is described in i.MX53 Security Reference Manual

< http://www.freescale.com/webapp/sps/download/mod_download.jsp?colCode=MCIMX53SRM >

Best regards

chip

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