Design Con 2015
Breaking News
Comments
Newest First | Oldest First | Threaded View
bk11
User Rank
Manager
re: Sleep current is, to a first approximation, irrelevant
bk11   4/25/2014 2:46:55 PM
NO RATINGS
It really depends on the application.  This month I experienced two instances of battery failure in devices where sleep current largely defines the battery life.  In both cases, a CR2025 is used to drive a micro that sleeps until a key is pressed.

The first instance, a DVD player remote control, died at about a year old.  The control was found under some books, and had been there a while, likely pressing buttons the whole time.  If that hadn't happened, I suspect the battery might have outlasted the player.

The second was the key fob transmitter on a 10 year old car.  I've had the car since new, so I know the battery had never been replaced.  The dead battery showed a few millivolts, and the new battery stopped working after a couple of days.  I measured the sleep current, and it was way too high to support a 10-year battery life.  Scrubbing the PCB with flux remover dropped the sleep current to a much more reasonable level.  I was going to replace the battery in the second fob (which gets more use) but I think I'll wait until it (or the car) dies just to see what the lifetime is.

I think in both of these cases, the battery would normally have outlived the device, or at least the original owner, making it essentially maintenance-free to the original customer.

alex_m1
User Rank
CEO
Re: Useful current draw
alex_m1   4/25/2014 12:05:17 PM
NO RATINGS
True.

And one cn do better than 200ua/mhz. energy micro takes 150ua/mhz in active mode and 45ua/mhz in automated peripherial mode. And the peripheral cans do interesting things on their own.

dt_hayden
User Rank
CEO
Useful current draw
dt_hayden   4/25/2014 10:56:57 AM
NO RATINGS
The statement about 10mA draw based on 200uA/MHz and maximum clock rate of 48MHz not being useful is pretty misleading.  Quite a lot can be done with microcontrollers running at less than their maximum clock speeds, although wasteful programming and inefficient compliers can certainly result in the requirement to run at full speed.    Efficient design practices generally payoff in less power, less rfi, less heat, and possibly smaller size/less weight.

The information about the internal resistance change is interesting.  We saw a similar issue when looking for supercapacitors to power SSDs during power interruptions.

dt_hayden
User Rank
CEO
teaser article
dt_hayden   4/25/2014 10:47:54 AM
NO RATINGS
What is the purpose of putting a teaser article here with the rest of the article at another site?  Increased ad revenue?

AZskibum
User Rank
CEO
Re: Are vendors telling the truth?
AZskibum   4/25/2014 10:04:01 AM
NO RATINGS
It depends on the application. I can think of one in particular in which the product stays plugged into the AC mains 24/7 and the coincell is needed only to retain certain data in RAM during periods of power outage or when the product is moved from one room to another, which is infrequently. These products typically last a decade or longer without depleting the coincell.

Susan Rambo
User Rank
Blogger
Are vendors telling the truth?
Susan Rambo   4/25/2014 9:09:25 AM
NO RATINGS
Good story about investigating the claims of MCU vendors on cell battery life. Some of the claims are outrageous. We need more engineers helping debunk marketing claims.



Top Comments of the Week
Flash Poll
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
<b><a href=Betajet">

The Circle – The Future's Imperfect in the Present Tense
Betajet
5 comments
The Circle, a satirical, dystopian novel published in 2013 by San Francisco-based writer Dave Eggers, is about a large, very powerful technology company that combines aspects of Google, ...

Max Maxfield

Recommended Reads From the Engineer's Bookshelf
Max Maxfield
27 comments
I'm not sure if I read more than most folks or not, but I do I know that I spend quite a lot of time reading. I hate to be idle, so I always have a book or two somewhere about my person -- ...

Martin Rowe

Make This Engineering Museum a Reality
Martin Rowe
Post a comment
Vincent Valentine is a man on a mission. He wants to make the first house to ever have a telephone into a telephone museum. Without help, it may not happen.

Rich Quinnell

Making the Grade in Industrial Design
Rich Quinnell
16 comments
As every developer knows, there are the paper specifications for a product design, and then there are the real requirements. The paper specs are dry, bland, and rigidly numeric, making ...

Special Video Section
The LT8640 is a 42V, 5A synchronous step-down regulator ...
The LTC2000 high-speed DAC has low noise and excellent ...
How do you protect the load and ensure output continues to ...
General-purpose DACs have applications in instrumentation, ...
Linear Technology demonstrates its latest measurement ...
10:29
Demos from Maxim Integrated at Electronica 2014 show ...
Bosch CEO Stefan Finkbeiner shows off latest combo and ...
STMicroelectronics demoed this simple gesture control ...
Keysight shows you what signals lurk in real-time at 510MHz ...
TE Connectivity's clear-plastic, full-size model car shows ...
Why culture makes Linear Tech a winner.
Recently formed Architects of Modern Power consortium ...
Specially modified Corvette C7 Stingray responds to ex Indy ...
Avago’s ACPL-K30T is the first solid-state driver qualified ...
NXP launches its line of multi-gate, multifunction, ...
Doug Bailey, VP of marketing at Power Integrations, gives a ...
See how to ease software bring-up with DesignWare IP ...
DesignWare IP Prototyping Kits enable fast software ...
This video explores the LT3086, a new member of our LDO+ ...
In today’s modern electronic systems, the need for power ...