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Registered Member #14
Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383
Steve McConner wrote ...
Well, they would convert the circuit design hassle into assembly programming hassle.
Atmel sell a range of tiny AVRs designed to drive lamp ballasts and the like. I think they have that niche.
With internal switch and sinchronous rectifiers?
Steve McConner wrote ...
It must be an inverting converter with positive input and negative output. The only buck-boost converters with positive input and positive output are the Cuk and SEPIC, and they both require two inductors, but your board only has one.
The LM3410 doesn't seem to do inverting.
How it is possible that it uses direct negative-ground connection? It can be only boost or only buck, or SEPIC, but i don't see two inductors and the only capacitors are tied to negative ground...
The solution must be simple but brilliant...
EDIT:
What it the "inductor" is in reality a small transformer? using a flyback topology? It could make sense.
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
See the last picture in the microflexdrive manual, there appears to be a BGA IC in the shadow of the inductor, between the ceramic caps. I found hints that the flexdrive was based on the TPS63010 , which is in a tiny 20-pin BGA that looks to be about the right size. It's a grounded-input grounded-output buck boost converter, so it makes sense. The SOT23-5 chip on the other side of the board might be a current sense amplifier or something like that.
Registered Member #14
Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383
Anders M. wrote ...
See the last picture in the microflexdrive manual, there appears to be a BGA IC in the shadow of the inductor, between the ceramic caps. I found hints that the flexdrive was based on the TPS63010 , which is in a tiny 20-pin BGA that looks to be about the right size. It's a grounded-input grounded-output buck boost converter, so it makes sense. The SOT23-5 chip on the other side of the board might be a current sense amplifier or something like that.
The 5-pin chip gets hot according to forum discussion under heavy load. In fact people make efforts in heatsinking it as good as possible (also the manual says it). But the difference amplifier makes sense, since the output is grounded.
Registered Member #1334
Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615
TheMerovingian wrote ...
I came across those small switchmode constant currend power supplies with buck-boost capabilities and I want to replicate some similar...
I suspect this is based on the TPS61040/TPS61041 - I have used exactly these devices for constant current sources for laser diodes. Should also say that I really like these chips as a general purpose LV switcher - they are just very nice & easy...
In fact, my youngest son & I have just made an anodising setup so that we can turn nice knurled laser pens and anodise them with nice colours as a little side-line for him...
Registered Member #14
Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383
Nicko wrote ...
TheMerovingian wrote ...
I came across those small switchmode constant currend power supplies with buck-boost capabilities and I want to replicate some similar...
I suspect this is based on the TPS61040/TPS61041 - I have used exactly these devices for constant current sources for laser diodes. Should also say that I really like these chips as a general purpose LV switcher - they are just very nice & easy...
In fact, my youngest son & I have just made an anodising setup so that we can turn nice knurled laser pens and anodise them with nice colours as a little side-line for him...
Cheers
THe front IC is the TPS63010 as shown in photo. THe 5 pin device may be de-facto the IC you have pointed out (heatsinking) , it is unclear why it is designed this way.
I have found valid alternatives to the TPS63030 in a more convenienta package, small but solderable (i have used a similar ic , the TPS61200DRCT 3.25 x 3.25 footprint, in a similar package for a micro dc-dc boost converter for DAFC single cells to power 3.3V leds).
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Tiny DC-DC constant current switching power supply
