MOSFET Half-Bridge Connection

flux

1:35

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You don’t need diodes there—the pull-up resistors already isolate the gate from a hard short to 28 V. When the transistor pulls the gate down, it only sinks current through the resistor, not straight to ground.
For example:

Table

Gate-nodePull-up resistorPull-down pathResulting current
Q2 GateR9 (100 kΩ to 28 V)Transistor or logic sink through R5I ≈ 28 V / 100 kΩ = 0.28 mA
Q1 GateR10 (100 kΩ to 28 V)Transistor or logic sink through R6I ≈ 28 V / 100 kΩ = 0.28 mA
  • A short is near-zero ohms; your 100 kΩ resistor prevents that.
  • If the gate-driver transistor (or logic) turns on, it simply pulls the gate low through the resistor, drawing ≈0.3 mA.
  • Adding a diode wouldn’t stop any dangerous current—it’d just clamp the gate a diode-drop above ground, but the resistor already limits current safely.
In short: the resistors do the job of isolation and pull-up/pull-down. No extra diodes are required.
Gate resistor spec
Transient suppression
Label nets
Check gate leakage
Place decoupling caps
281 days
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