Complementary PWM in LPC19 Series

[lpcware]

Content originally posted in LPCWare by Ranjith Shanbhag on Tue Jun 02 06:36:13 MST 2015
Hi,

We are working on the synchronous buck converter application using "LPC1549JBD100E". We need to use separate PWM outputs with complementary features to control 8 MOSFET's. We wanted to control all 8 MOSFET's using different PWM chanels i.e. different duty cycles with programmable/configurable dead time. We have noticed "Up to 8 single-edge or dual-edge controlled PWM outputs with independent duty cycles and common PWM cycle length" as per LPC user manual (please refer LPC15xx User manual, page no.222).

Please let us know how to implement the complementary PWM to control 8 MOSFET's(4 TOP and 4 Bottom) in our synchronous buck converter.


Thanks,
Ranjith R Shanbagh

[lpcware]

Content originally posted in LPCWare by mc on Mon Jun 08 09:24:57 MST 2015
Hi Ranjith,
SCT0 and SCT1 can generate upto 8 PWM each,whereas SCT2 and SCT3 upto 6 PWM each. In  center aligned mode, it is easy to generate dead time. One match register will determine the frequency of PWM and other two match registers can be used for duty cycle of complementary PWM.

[lpcware]

Content originally posted in LPCWare by Ranjith Shanbhag on Wed Jun 03 00:39:31 MST 2015
Hi,

Thanks for your Feedback.


whether it is possible to generate complementary PWM-with-deadtime for two channels using only SCT0 or SCT1 or SCT2 or SCT3????

[lpcware]

Content originally posted in LPCWare by starblue on Tue Jun 02 08:56:40 MST 2015
Did you look at the SCT cookbook? Not exactly what you need, but the PWM-with-deadtime example for two channels could be a start.
http://www.nxp.com/documents/application_note/AN11538.zip