ZHCSGO0A June 2017 – February 2024 TPS549B22
PRODUCTION DATA
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Though operating the TPS549B22 within absolute maximum ratings without ringing reduction techniques is possible, some designs can require external components to further reduce ringing levels. This example uses two approaches: a high frequency power stage bypass capacitor on the VIN pins, and an R-C snubber between the SW area and GND.
The high-frequency VIN bypass capacitor is a lossless ringing reduction technique which helps minimizes the outboard parasitic inductances in the power stage, which store energy during the low-side MOSFET on-time, and discharge after the high-side MOSFET is turned on. For this example two 2.2-nF, 25-V, 0603-sized high-frequency capacitors are used. The placement of these capacitors is critical to the effectiveness. The excellent placement is shown in Figure 8-1.
Additionally, an R-C snubber circuit is added to this example. To balance efficiency and spike levels, a 1-nF capacitor and a 1-Ω resistor are chosen. In this example a 0805-sized resistor is chosen, which is rated for 0.125 W, nearly twice the estimated power dissipation. See Snubber Circuits: Theory, Design and Application for more information about snubber circuits.