Folks,
Trying to use a MC34063 as a current source I found that it works well on the simulator but does not in real life. What I did is essentially running it "pedal to the metal", inverting input grounded, and letting it limit the inductor peak current.
What happens is that it drops around 70% in linear regulator fashion, nothing in there oscillates and, of course, this gets it hot.
Is there some undocumented pathology that prevents the thing from working when "floored"?
-- Regards, Joerg http://www.analogconsultants.com/
How, pray tell, are you doing that? Schematic? Even an LTspice schematic will do >:-} ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
The touchstone of liberalism is intolerance
Got a sim to run?
I built a wideband switching current source that simulated nicely and worked badly.
Gave up and went linear.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
On 2016-04-05 19:48, John Larkin wrote:
Yes, got a sim but it only works if you have the MC34063 model. I'll add those in another post. The whole thing is a bicycle light I wan't to built for my montain bike and then also my road bike. You can't buy such lights. I'll try to post the model and symbol in the next post:
Version 4 SHEET 1 880 680 WIRE -1520 -816 -1520 -864 WIRE -1168 -800 -1168 -864 WIRE -1360 -752 -1360 -864 WIRE -1520 -704 -1520 -736 WIRE -1424 -704 -1520 -704 WIRE -1360 -640 -1360 -656 WIRE -1168 -640 -1168 -720 WIRE -1168 -640 -1360 -640 WIRE -1520 -608 -1520 -704 WIRE -1360 -608 -1360 -640 WIRE -704 -528 -800 -528 WIRE -656 -528 -704 -528 WIRE -528 -528 -656 -528 WIRE -400 -528 -528 -528 WIRE -1360 -512 -1360 -544 WIRE -800 -512 -800 -528 WIRE -1520 -496 -1520 -528 WIRE -704 -480 -704 -528 WIRE -656 -480 -656 -528 WIRE -624 -480 -656 -480 WIRE -400 -480 -400 -528 WIRE -400 -480 -432 -480 WIRE -1360 -384 -1360 -448 WIRE -1232 -384 -1360 -384 WIRE -704 -384 -704 -400 WIRE -704 -384 -1152 -384 WIRE -624 -384 -704 -384 WIRE -400 -384 -432 -384 WIRE -256 -384 -400 -384 WIRE -208 -384 -256 -384 WIRE -80 -384 -128 -384 WIRE 112 -384 -80 -384 WIRE -1360 -368 -1360 -384 WIRE -256 -352 -256 -384 WIRE -80 -352 -80 -384 WIRE 112 -336 112 -384 WIRE -800 -288 -800 -432 WIRE -800 -288 -944 -288 WIRE -752 -288 -800 -288 WIRE -656 -288 -752 -288 WIRE -624 -288 -656 -288 WIRE -400 -288 -432 -288 WIRE -752 -272 -752 -288 WIRE -400 -272 -400 -288 WIRE -256 -256 -256 -288 WIRE -80 -256 -80 -288 WIRE 112 -256 112 -272 WIRE -1360 -192 -1360 -288 WIRE -1328 -192 -1360 -192 WIRE -1056 -192 -1136 -192 WIRE -624 -192 -656 -192 WIRE -400 -192 -400 -208 WIRE -400 -192 -432 -192 WIRE -752 -176 -752 -208 WIRE -656 -176 -656 -192 WIRE -400 -176 -400 -192 WIRE -944 -144 -944 -288 WIRE -1328 -96 -1504 -96 WIRE -1056 -96 -1056 -192 WIRE -1056 -96 -1136 -96 WIRE -1056 -80 -1056 -96 WIRE -944 -48 -944 -64 WIRE -1504 0 -1504 -96 WIRE -1360 0 -1504 0 WIRE -1328 0 -1360 0 WIRE -1104 0 -1136 0 WIRE -1104 16 -1104 0 WIRE -1328 96 -1360 96 WIRE -1104 96 -1104 80 WIRE -1104 96 -1136 96 WIRE -1360 112 -1360 96 WIRE -1104 112 -1104 96 FLAG -400 -176 0 FLAG -256 -256 0 FLAG -400 -384 SwE FLAG -656 -288 Vcc FLAG -656 -192 Inv FLAG -528 -528 SwC FLAG -752 -176 0 FLAG -400 -288 Osc FLAG -656 -176 0 FLAG 112 -256 0 FLAG -1104 112 0 FLAG -1360 0 Vcc FLAG -1360 112 0 FLAG -1056 -80 0 FLAG -80 -256 0 FLAG -1520 -496 0 FLAG -1520 -864 VCC FLAG -1360 -864 VCC FLAG -1168 -864 VCC FLAG -944 -48 0 SYMBOL voltage -944 -160 R0 WINDOW 123 0 0 Left 2 WINDOW 39 31 105 Left 2 WINDOW 0 32 32 Left 2 WINDOW 3 32 80 Left 2 SYMATTR SpiceLine Rser=0.1 SYMATTR InstName V1 SYMATTR Value PULSE(0 8.4 0 30m 30m 10m 100m) SYMBOL cap -768 -272 R0 SYMATTR InstName C2
SYMBOL res -784 -416 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R1 SYMATTR Value 1 SYMBOL MC33063A -528 -336 M0 WINDOW 0 0 176 Center 2 SYMATTR InstName X1 SYMBOL cap -416 -272 R0 SYMATTR InstName C3 SYMATTR Value 1000p SYMBOL schottky -272 -288 M180 WINDOW 0 24 64 Left 2 WINDOW 3 25 0 Left 2 SYMATTR InstName D1 SYMATTR Value MBRS130L SYMATTR Description Diode SYMATTR Type diode SYMBOL ind -224 -368 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 5 56 VBottom 2 WINDOW 39 56 56 VTop 2 SYMATTR InstName L1
SYMATTR SpiceLine Rser=0.1 Rpar=10k SYMBOL LED -96 -352 R0 SYMATTR InstName D2 SYMATTR Value LXK2-PW14 SYMATTR Description Diode SYMATTR Type diode SYMBOL cap 96 -336 R0 SYMATTR InstName C1
SYMBOL res -720 -496 R0 SYMATTR InstName R3 SYMATTR Value 1k SYMBOL MC33063A -1232 -48 M0 WINDOW 0 0 176 Center 2 SYMATTR InstName X2 SYMBOL cap -1120 16 R0 SYMATTR InstName C5
SYMBOL res -1376 -384 R0 SYMATTR InstName R4 SYMATTR Value 10k SYMBOL diode -1376 -608 R0 SYMATTR InstName D3 SYMATTR Value 1N4148 SYMBOL diode -1376 -512 R0 SYMATTR InstName D4 SYMATTR Value 1N4148 SYMBOL res -1248 -368 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R2 SYMATTR Value 4k SYMBOL pnp -1424 -656 M180 SYMATTR InstName Q1 SYMATTR Value 2N3906 SYMBOL res -1536 -832 R0 SYMATTR InstName R5 SYMATTR Value 1k SYMBOL res -1536 -624 R0 SYMATTR InstName R6 SYMATTR Value 10k SYMBOL res -1184 -816 R0 SYMATTR InstName R7 SYMATTR Value 1MEG TEXT -984 -568 Left 2 !.tran 0 80m 1n TEXT -664 -16 Left 2 ;C5 at 0.047u only for sim TEXT -664 16 Left 2 ;Set to 47uF for 1sec periods
Subcircuit for MC34063:
Version 4 SHEET 1 880 680 WIRE -1520 -816 -1520 -864 WIRE -1168 -800 -1168 -864 WIRE -1360 -752 -1360 -864 WIRE -1520 -704 -1520 -736 WIRE -1424 -704 -1520 -704 WIRE -1360 -640 -1360 -656 WIRE -1168 -640 -1168 -720 WIRE -1168 -640 -1360 -640 WIRE -1520 -608 -1520 -704 WIRE -1360 -608 -1360 -640 WIRE -704 -528 -800 -528 WIRE -656 -528 -704 -528 WIRE -528 -528 -656 -528 WIRE -400 -528 -528 -528 WIRE -1360 -512 -1360 -544 WIRE -800 -512 -800 -528 WIRE -1520 -496 -1520 -528 WIRE -704 -480 -704 -528 WIRE -656 -480 -656 -528 WIRE -624 -480 -656 -480 WIRE -400 -480 -400 -528 WIRE -400 -480 -432 -480 WIRE -1360 -384 -1360 -448 WIRE -1232 -384 -1360 -384 WIRE -704 -384 -704 -400 WIRE -704 -384 -1152 -384 WIRE -624 -384 -704 -384 WIRE -400 -384 -432 -384 WIRE -256 -384 -400 -384 WIRE -208 -384 -256 -384 WIRE -80 -384 -128 -384 WIRE 112 -384 -80 -384 WIRE -1360 -368 -1360 -384 WIRE -256 -352 -256 -384 WIRE -80 -352 -80 -384 WIRE 112 -336 112 -384 WIRE -800 -288 -800 -432 WIRE -800 -288 -944 -288 WIRE -752 -288 -800 -288 WIRE -656 -288 -752 -288 WIRE -624 -288 -656 -288 WIRE -400 -288 -432 -288 WIRE -752 -272 -752 -288 WIRE -400 -272 -400 -288 WIRE -256 -256 -256 -288 WIRE -80 -256 -80 -288 WIRE 112 -256 112 -272 WIRE -1360 -192 -1360 -288 WIRE -1328 -192 -1360 -192 WIRE -1056 -192 -1136 -192 WIRE -624 -192 -656 -192 WIRE -400 -192 -400 -208 WIRE -400 -192 -432 -192 WIRE -752 -176 -752 -208 WIRE -656 -176 -656 -192 WIRE -400 -176 -400 -192 WIRE -944 -144 -944 -288 WIRE -1328 -96 -1504 -96 WIRE -1056 -96 -1056 -192 WIRE -1056 -96 -1136 -96 WIRE -1056 -80 -1056 -96 WIRE -944 -48 -944 -64 WIRE -1504 0 -1504 -96 WIRE -1360 0 -1504 0 WIRE -1328 0 -1360 0 WIRE -1104 0 -1136 0 WIRE -1104 16 -1104 0 WIRE -1328 96 -1360 96 WIRE -1104 96 -1104 80 WIRE -1104 96 -1136 96 WIRE -1360 112 -1360 96 WIRE -1104 112 -1104 96 FLAG -400 -176 0 FLAG -256 -256 0 FLAG -400 -384 SwE FLAG -656 -288 Vcc FLAG -656 -192 Inv FLAG -528 -528 SwC FLAG -752 -176 0 FLAG -400 -288 Osc FLAG -656 -176 0 FLAG 112 -256 0 FLAG -1104 112 0 FLAG -1360 0 Vcc FLAG -1360 112 0 FLAG -1056 -80 0 FLAG -80 -256 0 FLAG -1520 -496 0 FLAG -1520 -864 VCC FLAG -1360 -864 VCC FLAG -1168 -864 VCC FLAG -944 -48 0 SYMBOL voltage -944 -160 R0 WINDOW 123 0 0 Left 2 WINDOW 39 31 105 Left 2 WINDOW 0 32 32 Left 2 WINDOW 3 32 80 Left 2 SYMATTR SpiceLine Rser=0.1 SYMATTR InstName V1 SYMATTR Value PULSE(0 8.4 0 30m 30m 10m 100m) SYMBOL cap -768 -272 R0 SYMATTR InstName C2
SYMBOL res -784 -416 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R1 SYMATTR Value 1 SYMBOL MC33063A -528 -336 M0 WINDOW 0 0 176 Center 2 SYMATTR InstName X1 SYMBOL cap -416 -272 R0 SYMATTR InstName C3 SYMATTR Value 1000p SYMBOL schottky -272 -288 M180 WINDOW 0 24 64 Left 2 WINDOW 3 25 0 Left 2 SYMATTR InstName D1 SYMATTR Value MBRS130L SYMATTR Description Diode SYMATTR Type diode SYMBOL ind -224 -368 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 5 56 VBottom 2 WINDOW 39 56 56 VTop 2 SYMATTR InstName L1
SYMATTR SpiceLine Rser=0.1 Rpar=10k SYMBOL LED -96 -352 R0 SYMATTR InstName D2 SYMATTR Value LXK2-PW14 SYMATTR Description Diode SYMATTR Type diode SYMBOL cap 96 -336 R0 SYMATTR InstName C1
SYMBOL res -720 -496 R0 SYMATTR InstName R3 SYMATTR Value 1k SYMBOL MC33063A -1232 -48 M0 WINDOW 0 0 176 Center 2 SYMATTR InstName X2 SYMBOL cap -1120 16 R0 SYMATTR InstName C5
SYMBOL res -1376 -384 R0 SYMATTR InstName R4 SYMATTR Value 10k SYMBOL diode -1376 -608 R0 SYMATTR InstName D3 SYMATTR Value 1N4148 SYMBOL diode -1376 -512 R0 SYMATTR InstName D4 SYMATTR Value 1N4148 SYMBOL res -1248 -368 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R2 SYMATTR Value 4k SYMBOL pnp -1424 -656 M180 SYMATTR InstName Q1 SYMATTR Value 2N3906 SYMBOL res -1536 -832 R0 SYMATTR InstName R5 SYMATTR Value 1k SYMBOL res -1536 -624 R0 SYMATTR InstName R6 SYMATTR Value 10k SYMBOL res -1184 -816 R0 SYMATTR InstName R7 SYMATTR Value 1MEG TEXT -984 -568 Left 2 !.tran 0 80m 1n TEXT -664 -16 Left 2 ;C5 at 0.047u only for sim TEXT -664 16 Left 2 ;Set to 47uF for 1sec periods
Symbol for MC34063:
Version 4 SymbolType BLOCK RECTANGLE Normal 96 160 -96 -160 TEXT 0 0 Center 2 MC33063A PIN -96 -144 LEFT 8 PINATTR PinName SwC PINATTR SpiceOrder 1 PIN -96 -48 LEFT 8 PINATTR PinName SwE PINATTR SpiceOrder 2 PIN -96 48 LEFT 8 PINATTR PinName Osc PINATTR SpiceOrder 3 PIN -96 144 LEFT 8 PINATTR PinName Com PINATTR SpiceOrder 4 PIN 96 144 RIGHT 8 PINATTR PinName Inv PINATTR SpiceOrder 5 PIN 96 48 RIGHT 8 PINATTR PinName Vcc PINATTR SpiceOrder 6 PIN 96 -48 RIGHT 8 PINATTR PinName Ipk PINATTR SpiceOrder 7 PIN 96 -144 RIGHT 8 PINATTR PinName DrC PINATTR SpiceOrder 8
Just a regular buck. Feedback (INV) to ground, the load is an LED that is to be driven in a (somewhat) constant current fashion. There is a 2nd MC34063 running flat-out but only used to regularly bump the current for an additional strobe effect. All for personal use, on my bicycles. Mainly so car drivers see me better and so dirt bikers don't crash into me on the trails.
I attached it in the response to John, then the MC34063 model schematic plus symbol in the 2nd response post to him. Got an Eagle schematic as well.
It's just for sports, normally one would use a micro controller for that. And I might if the 34063 turns out to be a dud.
-- Regards, Joerg http://www.analogconsultants.com/
There are specific LED switcher-driver chips. LTC has some, which means there will be LT Spice models and LT Spice reference designs.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Yes, for you and me that's easy. However, the motivation behind this was to make a very visible tail light that almost everyone in the world can copy without having access to Digikey or Mouser. With stuff they either already have or can easily scavenge out of discarded electronics. Once it works well and passes my personal trail tests (commercial lights generally don't) I want to post it on the web.
I also wanted it to be easily adaptable to higher voltage batteries. The guy on a rickshaw might not have the funds to buy a 8.4V Li-Ion battery.
-- Regards, Joerg http://www.analogconsultants.com/
Make it out of discretes!
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Guys, I got it going. Long story shory, a hair crack in a capacitor. Never had that before. The blink mode still doesn't work right but that's just a matter of resistor values.
-- Regards, Joerg http://www.analogconsultants.com/
12V SLA battery, 12V-to-110V modified sinewave inverter, 25W CFL, under-hood work light (to hold the CFL)?
:D
Michael
No kidding, I would. But I wanted it to fit into a housing of a cheap old-style tail light that can easily be found. So you have about one square-inch and 1/4" in height (but only on part of that surface). Also, nothing should become too hot and no electrolytics.
I got it going, it was a hair crack in a cap. Still have to adjust the blink mode. It is supposed to drop the steady background light and continue flash-only when the battery gets low. That way the rider will notice a low battery yet can continue home safely because the power consumption will drop way down. Even if that's still 10 miles up into the hills like in my case.
It is almost unbelievable how crude, flimsy and weak bicycle "lighting systems" are when compared to motor vehicles. I want to change that.
-- Regards, Joerg http://www.analogconsultants.com/
Gave up and went linear.
60Wh Li-Ion plus Cree XM-L run at 7.5W will do. That is what I have on the mountain bike. Once I waited at a red traffic light and a guy on a Harley pulled up next to me. He looked at my light, held his hand in front of his to muffle it, saw that mine outshined his big light and looked at me in disbelief.-- Regards, Joerg http://www.analogconsultants.com/
Ooh, nice!
Michael
To make a "current source" you need to regulate current >:-} ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
The touchstone of liberalism is intolerance
It sure is nice. At 7.5W it lights up a bush road or singletrack dirt trail bright enough to barrel down there at 15mph after dark. 20mph would be better but that would require 15-20W of LED lighting.
-- Regards, Joerg http://www.analogconsultants.com/
[LTSpice schematic]
That's what Isense is for. It regulates the inductor current. If you make the inductance large enough the ripple will be low and thus the LED current will become almost constant and independent of supply voltage. Which it now does after I found a hair crack in a capacitor. Which begs the question, how will ceramic multi-layer caps fare on a mountain bike that is used on quite brutal trails at speeds north of 15mph?
I've done this a lot with other chips, placing a brick on VFB and just regulating the peak inductor current. That can require handing out sick bags before a design review.
-- Regards, Joerg http://www.analogconsultants.com/
What's your target LED current? Looks like a job for an LM339 >:-} ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
The touchstone of liberalism is intolerance
About 100mA with 300mA peaks. An LM339 becomes like molasses when the battery voltage drops to 6V.
-- Regards, Joerg http://www.analogconsultants.com/
Hah, I believe that. When we reach the highway on return from our night hikes, my mate Kevin regularly gets flashed by cars who want him to dim his high-beams... three XM-L lights across his chest... even though they're turned down to 10% by then anyway. It's a custom-built rig with his own controller that even has digitised voice reporting.
I joke that he has to keep them turned down when the weather is dry, for fear of starting grass fires 100m away :)
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