You mean 9.375KHz phase-correct/18.75KHz fast PWM, Tom E?
AMC7135 PWM LED control – works? @ Pratik Panda
The aforementioned above link has errors on the period scale. Actual turn-on/turn-off times: 80μs/40μs.
Of course, 9.375/18.75KHz PWM frequency is outrageously fast (and wrong!) to drive AMC7135s. However, if you are to question my reasoning, have another cup of evidence:
HKJ's Test/Review of Qlite Rev.A 7135*8 Multiple Modes Circuit Board 3.04A
A little briefing of HKJ's quotes:
“The driver does not disable pwm at high.”
“Due to the fast pwm, the driver does not turn fully on. This makes the driver drop out of regulation at a fairly high voltage.”
“Due to the high pwm frequency, the curve it not square, but rounded.”
“In low mode the light is never in regulation.”
Fellows, the irregular shape and level of the regulator's output during the turn-on phase tells me its efficiency barely reaches 40% for that 8μs (turn-on) period.
With all of this in mind, it is clear to me that:
AMC7135's switching frequency is slow, so if PWMing them this has to be taken into account: slower PWM frequency (much slower!). I wouldn't go above 2-3KHz to minimize the impact on energetic efficiency.
0K. Time for a brief retreat.
Cheers ^:)
Originally posted on Thu, 12/08/2016 - 05:35; edited for fixups.