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UCC27511: Consult UCC27511 functional issues.

Part Number: UCC27511
Other Parts Discussed in Thread: UCC27517

Dear all:

    I have some functional issues about UCC27511。 

   1. The drive current specification is: 4-A Peak Source and 8-A Peak Sink. The current difference between the two is so large. How is this achieved?

   2. For Noninverting Input circuit, Can the power inductor be removed? if we want to output 3.5A or 4A drive current, how to choose VDD and VSOURCE voltage? What are the specifications of high-speed MOS tubes that require special attention (switching speed, node capacitance, Rdson), how to confirm the specifications?

   3. How does the actual drive current calculate the required current value based on the peripheral device and operating voltage?

  • Hello User,

    Thanks for your interest in our drivers.

    1. The asymmetry of the drive current specification is by design to optimize the turn-off of the MOSFET/IGBT where customers may want to asymmetrically drive their

    power devices, to achieve faster turn-off than turn-on in order to prevent shoot-through when driving complimentary FETs or to minimize Miller current related issues when dealing with IGBTs especially. ON the other hand, too high of gate current can cause overshoot at the gate resulting in EMI in the system and can generally be controlled by a series gate resistance. 

    If you're looking for a driver with symmetric drive strength, you may take a look at UCC27517 with 4-A/source/4A sink current capability from a single output. 

    2.  Are you asking how the drive strength varies with respect to supply range? What are you referring to with VSOURCE? 

    The peak current of the driver is highest at higher VDD levels typically >12V while maintaining the VDD within the recommended operating conditions.

    3. You can determine the required drive strength based on gate charge, desired turn-on/off times (i.e. 0.1us) by using dQ/dt = C * dVDD / dt = Ipk 

    where dQ=gate charge, dt = turn-on/off times, Ipk = peak current required out of the driver.

    You can estimate the peak current out of the driver from: Ipk = VDD / R where VDD = gate drive voltage and R = total impedance (internal + external) on the turn-on/off paths.