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I was reading about minimizing MOSFET switching loss when I came across an article by Texas Instrument on how to use negative voltage, instead of ground, to faster discharge MOSFET gate capacitance. To create the split voltage (say, +20 V/-5 V to charge/discharge Cgs), one of the schematics uses Zener circuit like below:

Texas Instrument ucc21520

In TI description, "If the isolated power supply, VA, is equal to 25 V, the turn-off voltage will be –5.1 V and turn-on voltage will be 25 V – 5.1 V ≈ 20 V... and there will be steady state power consumption from Rz." Can Rz be removed from the circuit?

Question solved by further reading into "Zener diode voltage stabilizer/regulator". Thank you for reading!

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    \$\begingroup\$ The Rz is a must. It allows the minimal current flow through the diode, so that it stabilises the voltage. It's a very basic zener diode voltage stabiliser, you can search on the web for this question. \$\endgroup\$
    – Marko Buršič
    Commented Mar 31, 2020 at 9:23
  • \$\begingroup\$ Thank you for your suggested keyword of "zener diode voltage stabiliser". \$\endgroup\$
    – bstack
    Commented Mar 31, 2020 at 9:34
  • \$\begingroup\$ You can also look for TIDA that has a little bit rearranged schematics and good explanation on this split power supply: ti.com/lit/ug/tidue55a/tidue55a.pdf \$\endgroup\$
    – Marko Buršič
    Commented Mar 31, 2020 at 9:36
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    \$\begingroup\$ @MarkoBuršič Your comment is the answer, though? \$\endgroup\$
    – Huisman
    Commented Mar 31, 2020 at 9:53

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