PF1550 increase OTP_POR_DLY

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PF1550 increase OTP_POR_DLY

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victorpecanins
Contributor II

Hello,

I'm designing a custom board with i.MX6 ULL & PF1550A6.According to datasheet:

At the end of the power-up sequence, the signal RESETBMCU is deasserted some time after the last regulator is brought up (time slot 3 for the A6 version). The delay of the reset signal is set by the register POR_DLY, that is loaded from the OTP memory register OTP_POR_DLY. In all the possible options, the PMIC is shipped with OTP_POR_DLY=2ms:

RESETBMCU is pulled high 2.0 ms to 1024 ms after the last regulator powers up. This
delay is OTP programmable through the OTP_POR_DLY[2:0] bits.

Now, the problem is, I find this time is a bit short and I want to increase it to at least 128ms, to allow the capacitors from  VDD_ARM_CAP & VDD_SOC_CAP to be fully charged before the CPU is released from RESET.

In the reference design, this problem is solved adding a reset supervisor, UM803RS, but I want to avoid using more external ICs and do it all with the PMIC.

The question is: How can I program the OTP_POR_DLY to 128ms? According to datasheet this should be possible, but it's not documented:

OTP (One time programmable) memory for device configuration
– User programmable start-up sequence, timing, soft-start and power-down sequence
– Programmable regulator output voltages and charger parameters

Thanks and best regards,

Victor

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reyes
NXP TechSupport
NXP TechSupport

Hi,

 

I consulted several related people and got the following answers:

 

OTP only allows one-time program since it burn in the fuses of device. There is no document about how-to OTP the PF1550.

 

NXP can OTP for customer for big opportunities (quantity around a million units). For lower qty, according to the applications engineers, our distributors can pre-program the PMICs with the desire configuration before they send them to the customer. Some distributors can program the parts for a cost.

 

Regards,

Jose

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victorpecanins
Contributor II

Hi Alberto thanks for your answer,

Then, please clarify this on the datasheet because it generates confusion among many customers:

OTP (One time programmable) memory for device configuration
– User programmable start-up sequence, timing, soft-start and power-down sequence

I would recommend to add some clarification such as "NXP can customize the OTP on demand."

Best regards,

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reyes
NXP TechSupport
NXP TechSupport

Hi Victor,

I'll contact the documentation and applications teams to see if they can add this information for the next revision of the datasheet.

Thanks for your feedback,

Jose

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victorpecanins
Contributor II

Dear Jose,

Thanks for your quick answer.

Now my question is about the procedure to write on the actual OTP registers. Just a regular I2C write to Addr 0x24 will work? How to connect the VDD_OTP pin? How many times can I program it since it's called OTP, but can be modified?

Thank you,

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reyes
NXP TechSupport
NXP TechSupport

Hi,

 

I consulted several related people and got the following answers:

 

OTP only allows one-time program since it burn in the fuses of device. There is no document about how-to OTP the PF1550.

 

NXP can OTP for customer for big opportunities (quantity around a million units). For lower qty, according to the applications engineers, our distributors can pre-program the PMICs with the desire configuration before they send them to the customer. Some distributors can program the parts for a cost.

 

Regards,

Jose

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reyes
NXP TechSupport
NXP TechSupport

Hi Victor,

Yes, OTP_POR_DLY can be configured to 128ms by OTP programming the OTP_PMIC_CFG1 register ADDR 0x24 from the Register OTP bitmap, bits 4 to 2 (OTP_POR_DLY) to ‘101’, this way, RESETBMCU will go high 128 ms after last regulator.

Have a great day,

Jose

TIC

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