USB Connection for STM32F072C8T6

[Justin K.]

Posted on March 19, 2018 at 19:28

Hello,

I saw in the datasheet that the max USB voltage input for the STM32F072C8T6 is approximately 3.6 V. Since the USB data voltage can go up to 5 V, I was wondering how one would make the connection between the USB to this MCU. If a voltage translator is required, could you please recommend one for this MCU?

Or, am I incorrect and you can get away with just directly connecting the USB to the MCU USB data lines?

Thank you.

#usb #stm32f072c8t6 #stm32f0

[waclawek.jan]

Posted on March 19, 2018 at 22:19

Since the USB data voltage can go up to 5 V

No, it can't.

And no worry, even if there's some short on the cable: the DM/DP pins are 5-volt tolerant, see the pins table (they are FT type).

Btw. VDDIO2-USB transceiver operating voltage specification is for the *supply* voltage to the USB transceiver.

JW

[Justin K.]

Posted on March 20, 2018 at 04:51

Thank you for the info!

Just a quick follow up question. I noticed there is a 3V3 pull-up using a BJT in some of the schematics on one of the data lines, depending on if it's full or fast speed. Is this necessary and part of the required specs for the USB 2.0 when using the STM32 with USB interface capabilities?

[waclawek.jan]

Posted on March 20, 2018 at 16:15

The pullup is needed only for the 'F1; other families have it built-in.

The pullup may be fixed; the transistor-controlled version allows software-disconnect.

JW