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ADUM2250 Side 1 output Low compatible Question

Category: Hardware
Product Number: ADUM2250

The side 1 (Input) of ADUM2250 is I2C compatible, which has the output Low about 0.9V @current >0.5mA. Does it make a reliable communication with Microcontroller (MCU)?  Most of MCU has an input Low with max 0.33*Vdd, Vdd = 3.3V.  

If it were not reliable, could you suggest any solution for that?  Thank you.

Top Replies

  • Hi, 

    There is a video here that explains why it behaves this way if you're curious. 

    Communication is possible when the MCU specifies 0.3*Vdd or greater. Take care with PMBus devices that specify a minimum input VIL of 0.8V. The Vol of the isolator and Vil of the device will be incompatible in this case. 



  • Thank you. I have watched that video.  To be specific, I have the PIO_0_1 and PIO_0_2 /TRST of  MCU, LPC55S28JBD100K to connect with Side 1 (Input) of ADUM2250.  The Max input low is 0.3*3.3V =0.99V, which is marginal over the output of isolator. Is that 0.09V sufficient to ensure a reliable communication? 

  • The ADuM2250 will communicate with a device specified for 0.3*VDD. The ADuM2250 is fully bidirectional, so Side 1 make face the peripheral if its advantageous to do so. If the peripheral side bus is much shorter (and all devices on that side are compatible) it may be better to face Side1 with weaker drive strength towards the peripheral.