Proper PCB layout is extremely important in a high-current, fast-switching circuit to provide appropriate device operation and design robustness. The UCC27332-Q1 gate driver incorporates short propagation delays and powerful output stages capable of delivering large current peaks with very fast rise and fall times at the gate of power switch to facilitate voltage transitions very quickly. Very high di/dt can cause unacceptable ringing if the trace lengths and impedances are not well controlled. The following circuit layout guidelines are recommended when designing with these high-speed drivers.

• Place the driver device as close as possible to power device to minimize the length of high-current traces between the driver output pins and the gate of the power switch device.
• Place the bypass capacitors between VDD pin and the GND pin as close to the driver pins as possible to minimize trace length for improved noise filtering. TI recommends having two capacitors; a 100-nF ceramic surface-mount capacitor placed less than 1mm from the VDD pin of the device and another ceramic surface-mount capacitor of few microfarads added in parallel. These capacitors support high peak current being drawn from VDD during turnon of power switch. The use of low inductance surface-mount components such as chip capacitors is highly recommended.
• The turnon and turn-off current loop paths (driver device, power switch and VDD bypass capacitor) should be minimized as much as possible in order to keep the stray inductance to a minimum. High di/dt is established in these loops at two instances – during turnon and turn-off transients, which induces significant voltage transients on the output pins of the driver device and gate of the power switch.
• Wherever possible, parallel the source and return traces of a current loop, taking advantage of flux cancellation
• Separate power traces and signal traces, such as output and input signals.
• To minimize switch node transients and ringing, adding some gate resistance and/or snubbers on the power devices may be necessary. These measures may also reduce EMI.
• Star-point grounding is a good way to minimize noise coupling from one current loop to another. The GND of the driver should be connected to the other circuit nodes such as source of power switch, ground of PWM controller, and so forth, at a single point. The connected paths should be as short as possible to reduce inductance and be as wide as possible to reduce resistance.
• Use a ground plane to provide noise shielding. Fast rise and fall times at OUT pin may corrupt the input signals during transitions. The ground plane must not be a conduction path for any current loop. Instead the ground plane should be connected to the star-point with one trace to establish the ground potential. In addition to noise shielding, the ground plane can help in power dissipation as well.