Long Press 4sec power down feature in MC34708 PMIC (i.MX535 with MC34708 design)

[SrideviK]

In my custom hardware, which is based on i.MX535 with M34708 PMIC, the OTG port is used as device only for programming using MFG tool initially i.e., during production only.

After programming, anyway the end product requirement is to have only the host functionality. No device mode required.

Hence the OTG port is configured in the OS to perform Host functionality only so that I can attach external devices.

Pls note that without VBUS power, this long press power down functionality works fine. But the USB section does not function.

Pls advice on the workaround for MC34708 so that power button 4 sec long press power down function can still work with the VBUS power applied to PMIC.

The MC34708 VBUS & VUSB power sections are attached for your reference. Both the VBUS & VINUSB are supplied from the 5V_Mains supply (DVDD_5V). Pls advice on the MC34708 register configurations to be done for making this 4sec long press power down feature with the VBUS power applied.

Looking forward for your immediate advice in this regard.

Thanks in advance.

Regards,

Sridevi

[igorpadykov]

Hi Sridevi

I am afraid this is not possible since just applying external voltage to VBUS

pin means "Turn ON" event, this is explained in MC34708 sect.7.5.3.4 Turn On Events:

"USB Attach: VBUS pulled high with corresponding interrupt and sense bits

USBDET and USBDETS. This is equivalent to

plugging in a USB cable connected to a host powering the VBUS line."

Note this behaviour is different from just powering from Battery since

it detects "Turn ON" only from crossing BP level, it allows

power button 4 sec function :

"Battery Attach: This occurs when BP crosses the LOWBATT threshold

which is equivalent to attaching a charged battery to the product."

Best regards

igor

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[SrideviK]

Dear Igor,

Pls advice on how to implement "Power Button System Reset" specified in section 7.5.3.5.

As per this section, I have enabled PWRONxRSTEN bits. But this function does not occur. Pls clarify how to implement this or what could be the problem behind this.

Regards,

Sridevi