Well, I made another mistake ordering components. I'm trying to build a battery powered Arduino from components. I need a efficient low voltage drop 3.3V regulator. I brought this one from digikey:
It's got good electrical characteristics. But the package is totally too hard to integrate into a prototyping board. I'm a newbie obviously. Can someone help me find inexpensive 3.3 voltage regulator that's really efficient?
Thanks!
Those are cheap efficient ones, look at the step-up/step-down or step-up ones since you are doing a battery application. However, they are not as cheap as an LM7805/7803 which are not efficient.
Yes, What you want is an MCP1703 from Microchip it's available in TO-92, SOT-223... Easily done with batteries as the input voltage range is 3.9 to 16V and the quiescent current is 2 uA... Microchip might well sample a few.. The data sheet is attached.
Doc
MCP1703.pdf (501 KB)
Thanks. So, it looks like if I'm trying to keep components on top of a prototype board with standard breadboard spacing, should stick with either "DIP" or "TO-xx" type packaging then?
Docedison:
Yes, What you want is an MCP1703 from Microchip it's available in TO-92, SOT-223... Easily done with batteries as the input voltage range is 3.9 to 16V and the quiescent current is 2 uA... Microchip might well sample a few.. The data sheet is attached.Doc
arusr:
Thanks. So, it looks like if I'm trying to keep components on top of a prototype board with standard breadboard spacing, should stick with either "DIP" or "TO-xx" type packaging then?Docedison:
Yes, What you want is an MCP1703 from Microchip it's available in TO-92, SOT-223... Easily done with batteries as the input voltage range is 3.9 to 16V and the quiescent current is 2 uA... Microchip might well sample a few.. The data sheet is attached.Doc
Yep, just make sure it is through hole with at least 0.1 inch spacing (Standard breadboard). If you check Digikey, it will almost always tell you what type of mounting it is, and will definitely tell you the packaging.
Ah, now I know why the LP3981 looked so cool. It has an enable line that was really great. When enable is off, it's consumes almost no current. I can use the digital output of ATMEGA328P to enable it, but keep it powered up all the time from the 4.5V battery source.
So, without an enable on the MCP 1703, I'll have to use a transistor to power the regulator up then? Battery voltage goes to top of transistor, digital out from ATMEGA goes to gate, and I power the MCP1703 only when I need to.
BTW, the 3.3V is powering a RFM69HW, a wireless transmitter which should only be needed 3 or 4 times a day. So I'd like to keep the voltage regulator off most of the time. The RFM69 uses 150mA.
Breakout board? Presumably, if you are using an LDO, the input voltage is a Lithium Ion rechargeable cell. So a maximum of about 4.20V. That translates to a worst-case efficiency of better than 70%, but that gets better as the cell voltage drops.
I'm not sure it is worth the extra cost and complexity of a switch mode buck regulator. In addition, the Pololu 300mA 3.3V regulator requires 5V minimum.
Switch mode regulators also tend to have very low efficiencies when you draw much less than their maximum rated current. LDO linear regulators (the low quiescent current ones, anyway) do -not- become less efficient with less current draw.
The suggested Microchip MCP1703 isn't really better than what you have, as it only seems to come in surface mount.
I made an error the part that I use is an MCP1702.. the numbers are the same.. 16.5 V input Max and 3.9V min @ 2 uA quiescent current... They can be purchased from Microchip direct for $0.48 Ea /0 - 25 pieces. The data sheet is attached. Here is the Link.. http://www.microchip.com/wwwproducts/Devices.aspx?product=MCP1702#pricindAndSamples
Doc
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I just find one interesting on kickstarter:
https://www.kickstarter.com/projects/pnmini/pnmini-positive-negative-power-supply-module-for-m
The efficiency goes to 92%. and it supports both positive and negative output.
I wonder why they don't make a TO version of the LP3981IMM. It's so perfect!!! I try to keep my hobby costs low, but my impatience and ignorance ends up making things more expensive. Arrrr.
I wonder if happygeek is using this forum to promote his kickstart project? Four posts and they're all about the kickstarter?
no.. it's not.. I wish I was..
happygeek:
I just find one interesting on kickstarter:https://www.kickstarter.com/projects/pnmini/pnmini-positive-negative-power-supply-module-for-m
The efficiency goes to 92%. and it supports both positive and negative output.
That depends, can you wait until May for the parts to be delivered. That assumes that the maker meets the schedule. Every single kickstarter project I have backed have been late. Originally I thought the Teensy 3.0 had been on time, but according to its creator, it was a few days late. However when it is compared to the weeks or months of delay I've seen in some other projects, it was very speedy.
In terms of having an enable pin, many of the pololu regulators have an enable pin (the low end regulators tend not to, but the multi-amp regulators do have an enable pin if memory serves).
arusr:
I wonder why they don't make a TO version of the LP3981IMM. It's so perfect!!! I try to keep my hobby costs low, but my impatience and ignorance ends up making things more expensive. Arrrr.
No one in industry is interested in through-hole packages for small parts
these days, those packages are maintained only for legacy components,
or high-power devices. Surface mount is cheaper, faster to assemble robotically,
electronically superior (lower stray inductance).
You need to obtain some break-out boards for common surface mount sizes (avoid the
fine-pitch ones to start with), SOIC8 is a good one to start with.
Some companies will sell you breakout boards pre-built with the chip of your choice,
although it probably costs a bit.
Any chance I can salvage the LP3981 by using breakout boards?
LP3981IMM-3.3/NOPB
datasheet: http://www.ti.com/lit/ds/symlink/lp3981.pdf
From the data sheet, I think I have the "VSSOP" type package. It's 8 pins, so "VSSOP8". But maybe it's not a standard package and only Texas Instruments makes the size.
I believe It is the same as TSSOP, at least according to Digikey. Just see if you can find an 8-pin break out board. (I'm not finding one with a quick search). I do know they exist however. A bigger one will also work, since you don't need to use all of the pins.
I've used this company. They sent me the wrong adapter, and sent two replacements by overnight mail. I will -definitely- be doing business with them again.
http://www.proto-advantage.com/store/product_info.php?products_id=2200046
Here is the breakout board with stainless steel stencil and solder paste.
http://www.proto-advantage.com/store/product_info.php?products_id=2210046