Custom AMC7135 Driver

[PilotPTK]

@Rufusbduck

Cool stuff, thanks for the look under the hood. Feels like I’m taking a break from working on my pinto to check out a Shelby

Glad you enjoyed the sneak-peak! Just remember, no-one builds up a Shelby as their first project!

PPtk

[AlexGT]

Great work! Where did you buy the thermal epoxy? How does it compare to arctic silver epoxy?

[PilotPTK]

@AlexGT

Great work! Where did you buy the thermal epoxy? How does it compare to arctic silver epoxy?

Thanks Alex. Compliment appreciated

The Wakefield Deltabond 155 can be bought from lots of Electronics distributors. Newark, for instance, is but one of them.
http://www.newark.com/wakefield-solutions/155/adhesive-epoxy-tube-6fl-oz-us/dp/00Z743

How does it compare to Arctic Silver Adhesive? Honestly - I wish I could say for sure. I can’t find (and I JUST looked again) any meaningful datasheet on the stuff.
http://www.arcticsilver.com/arctic_silver_thermal_adhesive.htm
I trust wakefield - they’ve been in the Thermal management game for a LONG time, and they’re well respected in applications way more important than overclocking a gaming computer. My opinion of Arctic silver has never been that high - It’s more of a marketing shill than anything. Additionally - Arctic silver fully admits that their material is quite electrically capacitive - that’s bad for some types of electronics (including buck/boost drivers). Kids overclocking their PC use Arctic Silver, Engineers and Scientists using Wakefield… There’s probably a reason

PPtk

[MRsDNF]

What to say? ORSM. I dont understand how the different components work but do understand what you wanted to achieve. Good stuff.

[Match]

PilotPTK,

In a word, Wow! Outstanding execution of design. It almost seems a pity to use it for a mere P60

[PilotPTK]

@Match

PilotPTK,

In a word, Wow! Outstanding execution of design. It almost seems a pity to use it for a mere P60

Match, coming from you, that is quite a compliment! Thank You!

I know, I know… But I like the P60 form-factor… I can’t help it

[ruffles]

Total respect for your work. I’m a little sad that you don’t want to commercialize these (you’d be right in line, price-wise with George’s Taskled drivers, fwiw), but there’s a lot to be said for not taking on an outlandish number of projects.

[JohnnyMac]

Amazing work, PPtk!! You never fail to impress.

[budynabuick]

@PilotPTK

@Match

PilotPTK,

In a word, Wow! Outstanding execution of design. It almost seems a pity to use it for a mere P60

Match, coming from you, that is quite a compliment! Thank You!

I know, I know… But I like the P60 form-factor… I can’t help it

+1! Me too. I don’t think that price ($25)is crazy at all.

Keith

[willie]

Bravo!!! Nothing like making something truly unique for yourself. Cheers, Willie

[nitro]

I’ll be buying tons if they were produced

[kramer5150]

WOW… that left me speachless. Very impressive work.

So your current levels are achieved by powering ON-OFF the 7135 chips independently?

Which side of the 7135 do you switch, the -B or +B… or both?

How well does each 7135 handle the “inrush” of current, or the current surge… with adjacent chips being turned on / off?

Sorry… I dont know how to read schematics very well… thanks!!

[E1320]

All I can say is AWESOME

[Ledsmoke]

HOT! It should have said hot!

As in :

"And does you host actually get that hot that you see a stepdown?"

I am sorry about the typo. I do most of my forum rummaging late evenings early nights and it does show from time to time.

Proof reading my own posts is something I tend to forget.

But thank you for the show and that you also have/take time to answer questions.

[PilotPTK]

@Ledsmoke

HOT! It should have said hot!

As in :

“And does you host actually get that hot that you see a stepdown?”

I am sorry about the typo. I do most of my forum rummaging late evenings early nights and it does show from time to time.

Proof reading my own posts is something I tend to forget.

But thank you for the show and that you also have/take time to answer questions.

That clarifies things a bit Happy to take the time - I’m glad you enjoy reading my ramblings.

P60 hosts don’t have much thermal mass - when running an XM-L at 3 Amps, thats (3 * battery voltage) Watts of heat (at 4.0V, 12 Watts) that gets generated between the emitter and the linear driver. A P60 can’t handle that for long without getting uncomfortably hot. 50C thermal-cut off will almost certainly trigger a step-down after some time of being on.

PPtk

[PilotPTK]

@E1320

All I can say is AWESOME

Glad you like! Quite a compliment coming from our resident Driver Provider

[PilotPTK]

@kramer5150

WOW… that left me speachless. Very impressive work.

So your current levels are achieved by powering ON-OFF the 7135 chips independently?

Which side of the 7135 do you switch, the -B or +B… or both?

How well does each 7135 handle the “inrush” of current, or the current surge… with adjacent chips being turned on / off?

Sorry… I dont know how to read schematics very well… thanks!!

Thank you, that’s very kind.

The 7135 has an on/off input that allows it to be turned on and off. The 7135 is perfectly comfortable being controlled even by high(ish)speed PWM so it’s designed to tolerate switching on and off frequently and rapidly. Because of the way these chips operate, they don’t “See” the current of other chips in parallel Electrically, they have no idea that they’re not all by themselves which means that adjacent chips have very little effect on each other.

PPtk

[bose301s]

@PilotPTK

@bose301s

Awesome, never worked with that particular uC but I know a lot of them do that. I haven’t done much circuit design actually. I wanted to possibly do that after school but took some MEMS classes and Physical Electronics and decided I wanted to get into actual device design more at the semiconductor/materials level, but I would still love to get into circuit design.

Pretty much all modern microcontrollers can use a PWM pin as a regular output. Most uC’s, in fact, have multi-purpose pins which can be setup to use several different internal peripherals - it’s not uncommon to find a pin, for instance, that can be configured as a Digital Input, a Digital Output, and Analog Input, an Analog Comparator Input, and maybe even an Analog (DAC) output. It allows the chip manufacturer’s to cram a ton of options into a small pin-count device.

This particular PIC is a pretty standard PIC16, actually. Very easy to setup and there are TONS of code examples available on the net for this family.

I, too, would love to gain more of a background in semiconductor design/fab, but I’m too deep into circuit design to part ways with it now. The closest I’ve ever gotten to wafer design is some work on ASICs - and that’s probably as close as I’ll ever get.

PPtk

So we’re pretty much the exact opposite of each other in that respect, lol.

[texaspyro]

One thing to be aware of with 7135 type chips… if you try and switch them off via the Vdd pin and an LED is connected, the circuit can still draw a couple of milliamps! The chip is spec’d with a standby current of 100 uA, but that is apparently with no load path connected. For the lowest possible standby current, you want to PWM/enable via an external FET.

[PilotPTK]

@texaspyro

One thing to be aware of with 7135 type chips… if you try and switch them off via the Vdd pin and an LED is connected, the circuit can still draw a couple of milliamps! The chip is spec’d with a standby current of 100 uA, but that is apparently with no load path connected. For the lowest possible standby current, you want to PWM/enable via an external FET.

Haven’t gotten it fired up yet (no time to write micro code), but if that’s true, that would suck. A lot. On a 17mm board, there just isn’t room for much more than I already have!

PPtk