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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 02:56pm 15 Sep 2017

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Hello folks.

While wading through the Microchip MAPS(Microchip Advanced Parts Selector) for a few things, I came across these very interesting looking LDO regulators:

MCP1755 LDO Regulator with PwrGood and Shutdown pins

They have a wide Vin of 3.6v to 16v, 300mA output current, standard output voltages of 1.8V, 2.5V, 3.0V, 3.3V, and 5.0V, 68 microamp quiescent current, only needs 1uF caps, True Foldback Current Protection, Short-circuit protection, Over-temperature protection and has PowerGood and ShutDown pins on the 5-pin versions of the device.

The latter two are very useful to have in many situations, but mainly the ShutDown pin I expect, as this allows the Micromite to switch the regulator off and on at will. In my case, I have projects where I use RF modules that sometimes don't have enable or sleep lines, and a regulator like this can do that job for you, along with supplying the needed voltage to the module, and is neater then using the MOSFET+NPN+Pullup method I have been using up until now.

The PowerGood pin could be used to let the Micromite know something had gone wrong with a device being powered from that regulator, if it tried to suck too much current or something.

Only 66c each. If you buy 26 or more, they drop to only 56c each!

Smoke makes things work. When the smoke gets out, it stops!

erbp
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Joined: 03/05/2016
Location: Australia
Posts: 195

Posted: 03:30pm 15 Sep 2017

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RS Components in Oz sell these at AU$1.00 for the 3.3v version (min qty 10) and AU$1.21 for the 5.0v version (min qty 6). They do free shipping (within Australia) on orders placed via the web.

I haven't used these devices but they do look interesting.

Phil.

Edit: To clarify - RS Components only stock the MCP1755S versions - these are the 3 pin versions that do NOT support the Power Good and Shutdown signals. Also the prices quoted above include GST, the prices on their website are ex GST.Edited by erbp 2017-09-17

CaptainBoing

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Joined: 07/09/2016
Location: United Kingdom
Posts: 2170

Posted: 08:02pm 15 Sep 2017

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things have come a long way since the 78xx series

68uA(!)Edited by CaptainBoing 2017-09-17

lew247

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Joined: 23/12/2015
Location: United Kingdom
Posts: 1702

Posted: 05:21am 16 Sep 2017

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Really nice
The only limitation is
[quote]300 mA Output Current for all output voltages[/quote]
Ideal for micromite but if you want to power other devices such as an Esp8266 no good you'd need another reg too

Grogster

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Posted: 07:55pm 17 Sep 2017

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Agreed. I tend to fall back on the LM1117 series of regulators, which you can get in several preset voltages, and they can do 800mA or so, and they come in a nice TO-252 package which is small, but still able to pass reasonable current and uses the PCB as a heatsink.

Smoke makes things work. When the smoke gets out, it stops!

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 08:12pm 17 Sep 2017

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If you want a means of switching power rails, look at the SY6280
It has adjustable current limiting and an enable pin.

Not a regulator and can switch 2.4 to 5.5 Volts.

Bought some to play with but still in the gunna-do pile.

Jim

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WhiteWizzard
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Joined: 05/04/2013
Location: United Kingdom
Posts: 2944

Posted: 09:10pm 17 Sep 2017

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TassyJim said ..... but still in the gunna-do pile.

I love that choice of wording

Grogster

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Location: New Zealand
Posts: 9610

Posted: 03:26pm 20 Sep 2017

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These seemed like a great deal till I went to buy them, and if you want less then a full reel(4000), it costs you US$10 re-reeling charge per part, so for two types of regulator, that adds US$20 to the cost which is substantial, really, and then freight on top of that.

Not quite so attractive anymore.

For the HC12 power switching I was planning to use them for, I think I will just reassign the pin I was going to use for the regulator shut-down line, to the SET line on the HC12, and software-sleep the module instead.

Smoke makes things work. When the smoke gets out, it stops!

redrok

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Joined: 15/09/2014
Location: United States
Posts: 209

Posted: 01:49pm 23 Sep 2017

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Hi Grogster;

Grogster said Hello folks.

Just a heads up on this regulator.
The spec calls for a minimum load current of 1mA for the voltage to stay within specification. So when running at 3.3V there should be a 3.3K resistor from VCC to GND.
This may be a problem if you want to run at extremely low power consumption.

Check "Note 2" in the speck sheet.

I see this in quite a few LDO regulators.

There are some that are specked to 0mA loads though.

redrokEdited by redrok 2017-09-24

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