Lowest power ARM MCU?

I'm looking for the lowest power ARM7 MCU out there... one with the
best mips/watt ratio. Its hard to compare the benchmarks used by
various manufacturers since they measure active Idd in various ways,
but the process technology (130nm, 90nm etc) is almost never specified.

I've been looking at the LPC2101 which I believe is built with a 90nm
process, but Ive heard there are intel parts that are built on 65nm
without having found one. I have a grand total budget of 1-2mW with
which I'm trying to get a 32-bit chip to control a 128x64 STN LCD. I
can run any chip at 32KHz, or even 1MHz, but more mips are always
better. Something above 64kbyte sram.

ghazanhaider wrote:
> I'm looking for the lowest power ARM7 MCU out there... one with the
> best mips/watt ratio. Its hard to compare the benchmarks used by
> various manufacturers since they measure active Idd in various ways,
> but the process technology (130nm, 90nm etc) is almost never specified.
>
> I've been looking at the LPC2101 which I believe is built with a 90nm
> process, but Ive heard there are intel parts that are built on 65nm
> without having found one. I have a grand total budget of 1-2mW with
> which I'm trying to get a 32-bit chip to control a 128x64 STN LCD. I
> can run any chip at 32KHz, or even 1MHz, but more mips are always
> better. Something above 64kbyte sram.

I don't think you will be interested in the Intel parts.  They are not
MCUs and require external program storage.  I believe the Atmel SAM7
parts have the lowest power level for a given MIPS.  You can find more
info in a comparison chart at www.gnuarm.com.  Go to the resources page
and scroll down to the ARM Chips section.  There you will find an ARM
MCU comparison chart with details such as power consumption.  It
displays better in Firefox than IE.  I believe the power numbers for
the Atmel parts assume you provide a separate Vcore voltage of 1.8
volts.  If you use the internal LDO the power levels will be higher.

I recall someone mentioning that there is an async part coming out that
will consume power according to your processing requirements.  It may
be Philips, I don't recall.  This would save you the trouble of
matching the clock to your MIPS requirement.

ghazanhaider wrote:
> I'm looking for the lowest power ARM7 MCU out there... one with the
> best mips/watt ratio. Its hard to compare the benchmarks used by
> various manufacturers since they measure active Idd in various ways,
> but the process technology (130nm, 90nm etc) is almost never specified.
>
> I've been looking at the LPC2101 which I believe is built with a 90nm
> process, but Ive heard there are intel parts that are built on 65nm
> without having found one. I have a grand total budget of 1-2mW with
> which I'm trying to get a 32-bit chip to control a 128x64 STN LCD. I
> can run any chip at 32KHz, or even 1MHz, but more mips are always
> better. Something above 64kbyte sram.

LPC3180  is the current leader, 90nm process, .9 V core, about
0.5mW/Mhz at 13Mhz(so I guess you can run it at 2-4 Mhz but the power
levels don't usually scale down linearly due to a fixed leakage
current) 128kb RAM, hardware floating point unit, like all leading edge
stuff, it is samples now, no production

http://www.standardics.philips.com/products/lpc3000/lpc3180/

oops,forget my post,  it's ARM9, you were looking for ARM7

I'd tend to think the 2101/2/3 would be your best bet. It also depends
on what on-chip peripherals are being used because this chip can power
down some of them when they aren't used. Also, sometimes the power
ratings are over the temperature range, and you can get better than
that with typical numbers. I think you're looking at 7 ma for 10 Mhz at
room temp. If you only need 1 Mhz it should be much lower than this.

Eric wrote:
> I'd tend to think the 2101/2/3 would be your best bet. It also depends
> on what on-chip peripherals are being used because this chip can power
> down some of them when they aren't used. Also, sometimes the power
> ratings are over the temperature range, and you can get better than
> that with typical numbers. I think you're looking at 7 ma for 10 Mhz
> at room temp. If you only need 1 Mhz it should be much lower than
> this.

AT91R40008 (256 kB internal SRAM) is 0,83 mW/MHz.
Recalc: 8,3 mW/10 MHz @ i1.V => 4.6 mA @ 25'C.

The LPC2101 would therefore be 50% more power hungry.

-- 
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB

Does Atmel have a device with flash that should be considered for low
power applications? Most modern Atmel Arm chips seem to target the high
integration market, and I figured they'd use a lot of current.

Since I have your attention, this might be a good time to ask about
upcoming products. Philips is very vocal about their lpc2888 and the
lpc23xx and lpc24xx upcoming devices. But I rarely see insights into
what Atmel is doing. Would it be possible for you to tell us what's
coming? My current desire is to use USB OTG (on-the-go)... but I
constantly look for low power devices also (non-usb, of course). I'd
like to trade-up from the MSP430 on one of my apps ...

On 30 Apr 2006 21:04:33 -0700, "ghazanhaider"
<ghazan.haider@gmail.com> wrote:

>I'm looking for the lowest power ARM7 MCU out there... one with the
>best mips/watt ratio. Its hard to compare the benchmarks used by
>various manufacturers since they measure active Idd in various ways,
>but the process technology (130nm, 90nm etc) is almost never specified.
>
>I've been looking at the LPC2101 which I believe is built with a 90nm
>process, but Ive heard there are intel parts that are built on 65nm
>without having found one. I have a grand total budget of 1-2mW with
>which I'm trying to get a 32-bit chip to control a 128x64 STN LCD. I
>can run any chip at 32KHz, or even 1MHz, but more mips are always
>better. Something above 64kbyte sram.

Have you considered another core?  The ARM wasn't designed for low
power operation, really. Ulf will tell you that Atmel is best, of
course :-)


PIC24 is a good compromise, with a wide instruction word (24 bits) but
16 bit data paths. It is (I believe) 0.25 micron. Not that geometry is
going to give you a reliable idea of consumption... It performs better
at 40 MHz than an ARM7 at 60MHz... Also has an excellent interrupt
structure and low cost tools... Its host port can be used for
interfacing to external LCD etc.

-Andrew M

Andrew M wrote:
> On 30 Apr 2006 21:04:33 -0700, "ghazanhaider"
> <ghazan.haider@gmail.com> wrote:
>
>> I'm looking for the lowest power ARM7 MCU out there... one with the
>> best mips/watt ratio. Its hard to compare the benchmarks used by
>> various manufacturers since they measure active Idd in various ways,
>> but the process technology (130nm, 90nm etc) is almost never
>> specified.
>>
>> I've been looking at the LPC2101 which I believe is built with a 90nm
>> process, but Ive heard there are intel parts that are built on 65nm
>> without having found one. I have a grand total budget of 1-2mW with
>> which I'm trying to get a 32-bit chip to control a 128x64 STN LCD. I
>> can run any chip at 32KHz, or even 1MHz, but more mips are always
>> better. Something above 64kbyte sram.
>
> Have you considered another core?  The ARM wasn't designed for low
> power operation, really. Ulf will tell you that Atmel is best, of
> course :-)
>

I just proved that Atmel can do better than the Philips 7 mA ;-)

BTW: the LPC2101 is not 90nm, it is 0,14 or 0,16
-- 
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB

Eric wrote:
> Does Atmel have a device with flash that should be considered for low
> power applications? Most modern Atmel Arm chips seem to target the high
> integration market, and I figured they'd use a lot of current.
>
> Since I have your attention, this might be a good time to ask about
> upcoming products. Philips is very vocal about their lpc2888 and the
> lpc23xx and lpc24xx upcoming devices. But I rarely see insights into
> what Atmel is doing. Would it be possible for you to tell us what's
> coming? My current desire is to use USB OTG (on-the-go)... but I
> constantly look for low power devices also (non-usb, of course). I'd
> like to trade-up from the MSP430 on one of my apps ...

You should have read my post above...

I believe the Atmel SAM7 MCU parts have the lowest power level for a
given MIPS.  You can find more info in a comparison chart at
www.gnuarm.com.  Go to the resources page and scroll down to the ARM
Chips section.  There you will find an ARM MCU comparison chart with
details such as power consumption.  It displays better in Firefox than
IE.