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From: John Larkin on 25 May 2010 13:28

Most cool:

http://www.onsemi.com/pub/Collateral/NSI45020-D.PDF

I've been wanting constant-current ICs for years. They are finally
starting to happen.

This is 51 cents, q1.

John

From: Jim Thompson on 25 May 2010 13:38
On Tue, 25 May 2010 10:28:42 -0700, John Larkin
<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:

>
>Most cool:
>
>http://www.onsemi.com/pub/Collateral/NSI45020-D.PDF
>
>I've been wanting constant-current ICs for years. They are finally
>starting to happen.
>
>This is 51 cents, q1.
>
>John

Fig 2 is pretty gross. Lousy headroom design. Sheeesh!

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

The only thing bipartisan in this country is hypocrisy
From: whit3rd on 25 May 2010 13:59
On May 25, 10:28 am, John Larkin
<jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote:

> http://www.onsemi.com/pub/Collateral/NSI45020-D.PDF
>
> I've been wanting constant-current ICs for years. They are finally
> starting to happen.

Current-regulator diodes aren't new. Siliconix was making 'em a
decade or more ago (just gate-source shorted JFETs).

J500 series and CR200 etc. were part numbers.

A grounded-base transistor with emitter resistor to negative supply
is cheaper and can do a wider range of currents than a fixed diode.
From: Jan Panteltje on 25 May 2010 14:07
On a sunny day (Tue, 25 May 2010 10:28:42 -0700) it happened John Larkin
<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in
<p22ov5d4ju2fn3pf69ttkvqru1s5aumsqe(a)4ax.com>:

>
>Most cool:
>
>http://www.onsemi.com/pub/Collateral/NSI45020-D.PDF
>
>I've been wanting constant-current ICs for years. They are finally
>starting to happen.
>
>This is 51 cents, q1.
>
>John

These dat 20 mA is a bit high for LEDs used as indicator.
I have some green ones now at 3.3V with 33k (!) in series,
the LEDs drop 2.38 and 2.44 V, so that makes .92 and .86 V over
the resistors, giving a current of about 28 uA, good visibiliy
in bright room light, JUST not blinding when you look directly into it.
ftp://panteltje.com/pub/low_current_LEDs_img_1964.jpg
The blue one is on 10% PWM with 180 Ohm in series on 3.3 V.
That current source product may not sell.
Resistors are cheaper.

From: Spehro Pefhany on 25 May 2010 14:17
On Tue, 25 May 2010 18:07:59 GMT, Jan Panteltje
<pNaonStpealmtje(a)yahoo.com> wrote:

>On a sunny day (Tue, 25 May 2010 10:28:42 -0700) it happened John Larkin
><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in
><p22ov5d4ju2fn3pf69ttkvqru1s5aumsqe(a)4ax.com>:
>
>>
>>Most cool:
>>
>>http://www.onsemi.com/pub/Collateral/NSI45020-D.PDF
>>
>>I've been wanting constant-current ICs for years. They are finally
>>starting to happen.
>>
>>This is 51 cents, q1.
>>
>>John
>
>These dat 20 mA is a bit high for LEDs used as indicator.
>I have some green ones now at 3.3V with 33k (!) in series,
>the LEDs drop 2.38 and 2.44 V, so that makes .92 and .86 V over
>the resistors, giving a current of about 28 uA, good visibiliy
>in bright room light, JUST not blinding when you look directly into it.
> ftp://panteltje.com/pub/low_current_LEDs_img_1964.jpg
>The blue one is on 10% PWM with 180 Ohm in series on 3.3 V.
>That current source product may not sell.
>Resistors are cheaper.

They appear to be aiming this at automotive applications where you
have a big difference in voltages depending on whether the engine
is operating or not-- especially important when you subtract a series
string of LED Vfs from it. Limited application area, but huge
potential in terms of picoacres* of silicon sold.

* 5mils x 5mils ~= 4 picoacres.

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