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UCC5350-Q1: UCC5350-Q1 internal Vcc1 supply voltage and IN+ pin voltage problem

Part Number: UCC5350-Q1
Other Parts Discussed in Thread: UCC5320


Regarding the Vcc1 supply voltage and IN+ pin voltage IN UCC5350-Q1 chip, according to Figure 9-8, IN+ and Vcc1 pins inside the chip are connected through a diode in the red box below:

1, when the IN+ voltage is 3.3V, after the voltage drop of the diode is transmitted to Vcc1, will the voltage of Vcc1 be greater than the minimum value of its supply voltage 3V? If it is greater than 3V, will it cause the chip to open in advance?

2. What is the diode voltage drop between the internal IN+ and Vcc1? When the IN+ voltage is 3.3V, how to assess the risk of early chip opening?

  • Hi Zhixia,

    Here is the measured IV information for that ESD cell on UCC5320:

    0.6 0.182
    0.65 0.756
    0.7 2.65
    0.75 6.93
    0.8 16.2
    0.85 33
    0.9 60
    0.95 99
    1 152
    1.05 210
    1.1 276
    1.15 350
    1.2 425

    Since the supply current is only 1mA, I think that the device will definitely be "ON" if IN+ reaches a value between 0.65V and 0.7V above the supply UVLO threshold. Which is usually 2.6V. 


    You might be okay with 3.3V, but as soon as it hits 3.35 to 3.34V the input will be powered through this ESD cell.

    Best regards,