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[ARM] LPC1769 Dead time control problem

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Newbie level 4
May 7, 2015
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Hai all..
I am using LPC1769 to generate PWM with dead time using MCPWM peripheral. The problem is normal PWM is max duty cycle is 48% , inverted PWM should be max duty cycle 48%. But inverted PWM is getting minimum 52% duty cycle. Dead time is 2usec. Can any one help me?

Define your drivers , switches and load ESR.

Skew occurs when Ciss rises with lower RdsOn for each stage.

I assume lpc1769 output RdsOn is 25 Ohm from recollection of Vol/Iol. See end of spec for actual values, and show schematic and waveforms with load ESR.

PWM.pngI am not using any drivers, just absorbed wave forms in scope. see the attached image.
pwm switching frequency = 10khz
dead time = 2usec
yellow color = PWM
Blue color = Inverted PWM

Good, now show output pins and how this complementary output is generated with load/no load.

Asymmetric delays are often created with series R and //diode to input Ciss for asymmetric delays to enhance deadtime. Driver Chips do this internally with single ended inputs.

LPC1769 has MCPWM peripheral. so, it will also generate complementary output. The complementary out put will get at GPIO pins.

Oh , ok, but they don't satisfy your need for deadtime, so try something else and contact OEM, your purchasing and/or Distributor support with an Incident Report.

Consider a bridge driver chip after you define the load specs.
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