IgorT
0
- Joined
- Oct 24, 2007
- Messages
- 4,177
- Points
- 0
Keep it platonic and all will be well.. :
LPF Donation via Stripe | LPF Donation - Other Methods
Links below open in new window
ArcticMyst Security by Avery
Driver Ideas. DC/DC stepup AND CCregulation
- Thread starter airy52
- Start date
for sure. Sooooo moving on...... high side amps, or something. Used to allow a negative ground so u can heatsing the diode ( case is negative) I dont understand how to incorporate one into woops schematic, or anything for that matter. or when you cannot ground the case..... or why. anyone know about this?
IgorT
0
- Joined
- Oct 24, 2007
- Messages
- 4,177
- Points
- 0
Why you can not ground the case is obvious from the schematic.. There is a resistor (Rsense) between the negative diode connection and battery ground. That resistor means, the diode leg is at a higher potential.
If you ground the diode base, you short the sense resistor, and the current will go up and kill the diode and/or the regulator.
With an op amp or a sensing IC, you can rearrange the circuit, so the diode base is at the ground, and the regulator still gets it's sense voltage from the amplifier.
In a metal host, you usually lose the heatsinking, if you insulate the AixiZ module. And you don't want to do that.
Luckily, this does not matter with PHR diodes, as the case is not connected to the internal parts.
If you ground the diode base, you short the sense resistor, and the current will go up and kill the diode and/or the regulator.
With an op amp or a sensing IC, you can rearrange the circuit, so the diode base is at the ground, and the regulator still gets it's sense voltage from the amplifier.
In a metal host, you usually lose the heatsinking, if you insulate the AixiZ module. And you don't want to do that.
Luckily, this does not matter with PHR diodes, as the case is not connected to the internal parts.
airy52 said:
I drew a schematic and designed a board for another chip here
http://www.laserpointerforums.com/forums/YaBB.pl?num=1209911140/24#33
but i never made it.
it would be pretty similar to implement with the TPS61200
to get a general idea of the layout look at the third example in my drawing back on the first page
I just had my last exam (YAY!!!) so i can spend some time creating a board with high side current sensing
Alright cool. I'm going over it, il post back when i understand it. I'm gonna try to figure it out without asking as many questions as I have. Thanks.
PS: dont design a circuit for the maxim yet I want to try to do it myself haha. if you do just dont show me I want it to be a challenge.
Thanks. PS: dont design a circuit for the maxim yet I want to try to do it myself haha. if you do just dont show me I want it to be a challenge.
I think even if we found a DC DC converter with everything we needed, low Vin Min, >600mA, buck-boost, current regulation through iLED or Ilim, and all that, it would still be just as easy to use the tps chip. I mean the fb is only .3v, its not much. Although with that first maxim chip, one nice thing is that it has two grounds, one for the circuit and one for powering the chip or something like that. So you dont have to worry about that high side amp, just use the different grounds. I think I'm going to run some tests and I'll let you know how it goes. Probably make a new thread with the chip in the title, I'll see what happens when Vin is > than Vout or the V needed. and some efficiency numbers. Just waiting on my chips. Those hardcore coilcraft people said the company i made up was not a real company but we'll see. anyone know a good way to get coilcraft coils? without paying obviousyl? Thanks!
but we'll see. anyone know a good way to get coilcraft coils? without paying obviousyl? Thanks!airy52 said:nyone know a good way to get coilcraft coils? without paying obviousyl?
well... I've got to say that the best way for one to get something of value is not through chicanery but by honestly paying for it. It may be obvious, but if everybody keeps trying to con Coilcraft or any other company, they will eventually be forced to either tighten up impossibly or just shut down the samples program altogether - then even honest developers will not be able to get them.
I understand when people really can't afford something. Really, I do - have been very poor in the past and am headed into another spell that may be permanent. But:
The coils are not very expensive. I paid only $6.60 for 30 inductors (10 uH, 1 Amp, 0.066 ohm - Taiyo Yuden part #P04SB100M at Newark)
That's .22 each - if you can't afford that, send me a pm and I'll send a couple your way.
DanQ
Hey, don't feel bad... you have a whole culture to buck changing the "get what you can, I want it!" approach ;-)airy52 said:I guess you're right danq.... But samples rock. and if you only need a few i'm usually okay with it. But I guess I'll order some. Now I feel bad....
I just loooked, and they have the 4.7uH version too - same price.
Newark is a great source. Sometimes I get stuff cheaper there than bargain bulk on eBay.
[edit - forgot to add: no minimum order or small-order handling fee! the only obstacle to tiny orders is postage - if you only buy 30 coils, postage will be about $5 via USPS]
yeah, but they are a business and don't just toss parts around - their packaging is amazing. Order a few more items from them and the postage per item is negligible. Need ceramic caps for that buck/boost? how 'bout $0.066 for a 10uf 25V? get 50 of 'em just for the heck of it - $3.30, that's less than a day's worth of ice cream [sub];-)[/sub]airy52 said:
???airy52 said:
did you notice that the link in the above posts goes to a Vishay part, not Coilcraft?
I'm just trying to tell you about a great supplier.
Note also that the specific parts I mentioned are useful in the circuit being discussed...
or were you kidding with that remark?
rkcstr
0
- Joined
- Dec 1, 2007
- Messages
- 1,368
- Points
- 0
yeah, Newark is typically the cheapest for ceramic caps and they typically have resistors close to any value I'm looking for, for about $0.007 each, so I usually by them by the 1000s, LOL. Their selection isnt great, but I usually check their prices before I go anywhere else since they're typically the cheapest. And their packaging IS amazing! Each component (even a single inductor) is put in its own bubble mailer within a box!
