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I want to use the Infineon IRPS5401, a Power Management IC with PMBUS functionality through the I2C protocol. Infineon suggests using the USB005 dongle https://www.infineon.com/dgdl/ug-usb005.pdf?fileId=5546d462533600a40153568485d32985 for programming purposes with the PowIRCenter software. The dongle is this: enter image description here (image from dongle's datasheet)

The PMIC programming guide describes the configuration circuit with all the hardware settings and connections for programming the PMIC: enter image description here

I want to build a custom PCB for the first programming of the IRPS5401 so if I understand correctly I must use the indicated circuit with the usb005 dongle from Infineon connected to the I2C Data and I2C Clock pins (and GND obviously).

enter image description here (Image from IRPS5401 datasheet with CLK, DATA, and VDDIO pins descriptions)

My problems are two:

  1. The 5V depicted for the sleep and Vcc pins.
  2. The 3.3/5 Vdc depicted for the Vddio pin and pull-up of SDA and SCL.

As I see from the first image, the dongle has 3 pins: GND, SDA, and SCL and hence I can't derive the I2C master voltage from it.

Do I need to plan in my custom-PCB an independent 3.3V for pull-up of I2C data and clock and VDDIO or a 5V?

I think that this depends on the voltage level of the I2C master but the dongle's documentation doesn't have much information about it.

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The USB005 I have in front of me includes pull-up to about 3.4 Vdc. I think technically you could program these without pull-up on SCL and SDA (as the dongle will provide it), but your final board needs pull-up if you intend to communicate with the PMICs during operation (from a MCU, etc).

If I understand your application your making a special board just for getting them programmed and then moving them over your final board. I think this is a good idea. Pullup to 3.3 Vdc on the final board can become a bit of a chicken and egg problem if you are relying on the a PMIC output to pull up to 3.3 Vdc. Not just because it wont be there until the PMIC is programmed, but also because several of the PMIC outputs are pulled to ground until they are programmed, causing problems because the I2C lines may be pulled to ground until the PMIC gets programmed.

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  • \$\begingroup\$ Even if the pull-ups were not an issue, the chip would still need the bus voltage to be present on VDDIO, presumably to set the internal threshold levels. Probably another 3v3 regulator can be used, a few hundred millivolts difference won't be an issue. \$\endgroup\$ – Chris Stratton Sep 16 at 15:16

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