const-current thing
in [Design]
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From: Jan Panteltje on 25 May 2010 14:23 On a sunny day (Tue, 25 May 2010 14:17:55 -0400) it happened Spehro Pefhany <speffSNIP(a)interlogDOTyou.knowwhat> wrote in <to4ov5pc8gp94cduuv5rmdncal7au9564c(a)4ax.com>: >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-- If I was to design foe in a car, I would have the electronics on a regulated supply. Output from a micro driving a LED would NO WAY go to an unregulated source. Interior lighting would be adjustable, color and brightness, so same story. For the headlights 10 mA is not enough. Small silicon farmland if you ask me :-) 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. > >
From: Hammy on 25 May 2010 14:23 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. According to the datasheet it's been around at least since Nov 2009 so it must be selling. Vishay makes the SST series. http://www.vishay.com/docs/70711/70711.pdf
From: John Larkin on 25 May 2010 15:13 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, I have a night light that's a Tadiran lithium cell with an Avago green LED and a 1.5M resistor. It should last at least 20 years. If you need more light, you can hold it in your mouth and bridge the resistor with your tongue. Hands-free adjustable dimming! John
From: Jan Panteltje on 25 May 2010 15:20 On a sunny day (Tue, 25 May 2010 12:13:05 -0700) it happened John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in <i58ov556i8fma9i12mha5b7nhcven5upr1(a)4ax.com>: >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, > >I have a night light that's a Tadiran lithium cell with an Avago green >LED and a 1.5M resistor. It should last at least 20 years. > >If you need more light, you can hold it in your mouth and bridge the >resistor with your tongue. Hands-free adjustable dimming! > >John In yoiur mouth? How about this tooth inspection LED? ftp://panteltje.com/pub/tooth_inspection_LED_img_1970.jpg hehe
From: Phil Hobbs on 25 May 2010 18:33
On 5/25/2010 1:38 PM, Jim Thompson wrote: > 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 Figure 5 is what has me worried. A 15% current decrease occurs over seconds. Great idea, no cigar for the implementation. Still, it's a lot cheaper than the LTC thing. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net |