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Class D Switching Power Amplifiers and Power D/A conversion

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Old 20th August 2009, 05:29 PM   #11
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Lucky you I've blown about 2dozen of driver chips (but not this type) to learn to use them. I found out some practical points about using driver IC.
- Supply pins of the driver IC must by bypassed by ceramic smd caps as near as possible to the pins. If possible, use uninterrupted ground plane for connecting all ground points of a classD amp. Ground plane around driver IC not necessarily mean 0V plane, but can also be -VCC plane
- Gate resistor value. I also found out about 22ohm is good practically. But this R must be high-dissipation (0.5Watt or more, I use smd 47ohm//47ohm to dissipate heat). Lower than this may blown the chip, higher give bad square wave or difficult to control dead time.
- We must put capacitor (I use 470nF) right directly from drain lead of upper mosfet to source lead of lower mosfet (I use pin-to-pin connection, to minimize lead length). It's like a bridge hovering between D-upper to S-lower mosfet. Extra ceramic capacitor from upper drain to ground and lower source to ground makes it better.
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