Well well, I may have to apologize to the humble 7135s…
I just reconfigured the driver and ran a test with the MCU (Attiny13A) completely bypassed. I simply tapped into the MCUs positive voltage supply (4.3v zener controlled) and fed that directly in the Vcc harness controlling the 48x 7135s. This would force them into a constant-on (high only) mode of operation.
The results are very telling. WE FINALLY HAVE PROPER REGULATION!!! and at a much lower voltage overhead than before.
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This graph shows the results of running the MCU-less setup off the iCharger at 8.7v, faded graph is the older test at the same voltage for comparison. Everything connected up the same way.
I thought my current meter had locked up for a moment there, couldn’t believe what I was seeing, solid stable regulation for almost 5minutes! At the full theoretical current limit of 17.85A, with the MCU active I had to feed the thing 9.1v! before it would show me those figures and then it only maintained it briefly.
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Of course I thoroughly verified my results with state of the art measuring equipment…
Yep, she’s flat alright :bigsmile:
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SOOOooo Attiny 13A, what the heck are you doing?? But certainly you’re not switching those 7135s with enough authority or something else fishy is going on. Maybe the Attiny doesn’t like the heat? Need to study it’s data sheet a bit and see what could be causing this. I assume we can trust that the STAR firmware is doing a good job at 100% duty cycle? I can’t wait for my little Rigol scope to finally get here so I can have a better look into what’s actually going on on the PWM line.
Thoughts welcome guys, I’m a little stumped as to what’s going on once again. But the finger is firmly pointed at the Attiny13A at this stage…
I am rather pleased to finally see some regulation and more expected performance from this setup, it just too bad I had to lose all my lower modes to get there…
Cheers
Linus
PS. I just checked and the annoying Warm up flicker is also completely gone running in this MCU-less configuration. Just solid stable output at much lower battery pack voltages.