Any beefy coil driver chips?

Yeah, that stuff went mostly custom. Automotive injectors aren't usually driven that hard either. Here is an interesting FET from that market, looks like they goofed up the CAD symbol:

--
Regards, Joerg

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For you amateurs... that's showing the built-in current limiting ;-)

...Jim Thompson

--
| James E.Thompson, P.E.                           |    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     |
             
 I love to cook with wine     Sometimes I even put it in the food

How about putting a thermistor in series? The coil energizes, the thermistor heats up. It's resistance goes up. Problem solved. If it's mass is small, it cools quickly for the next cycle, yet can be used as long as needed.

--
You can\'t have a sense of humor, if you have no sense!

I tried PIC16F684 using following code: (outputs 25 % duty cycle from pin RA5) Power up timer was turned off

;config 0x0FD4 include "P16F684.inc" clrf PORTA bsf STATUS,0x5 ;bank 1 bcf TRISA,0x5 bcf STATUS,0x5 ;bank 0

silmukka bsf PORTA,0x5 bcf PORTA,0x5 goto silmukka

end

The led on RA5 pin was first on 14,8 us after power up, so it executes first instruction about 10 us after power up.

Note power up timer must be off and there is no such option in 10F series. They take always 18 ms or 1 ms to start. I think cheapest Pic with this option is 12F609. (it is available as 8-lead DFN package).

On a sunny day (Sat, 01 Aug 2009 10:31:42 GMT) it happened "E" wrote in :

Yes, short init, very fast :-)

Did you use the 20MHz xtal or the internal osc?

There are a few issues though that Joerg would need to look in to.

1) How long will the FLASH last (temp etc). 2) How reliable does it start up, I have had one case (say in a few hundred), where my PIC based SWR meter gave wrong ADC readings after startup and subsequently a false SWR alert (still have a second SWR meter in the transmitter to compare). Power down and up again on the PIC box fixed it. So one needs to look at the correct rise times of Vd etc on the PIC to make sure the program always starts correctly. 3) The power down of the PIC must be 100% guaranteed, so it is not still running, or erratically running on low voltage, when the next pulse comes.

"Jan Panteltje" kirjoitti viestissä:h519mk$gm5$ snipped-for-privacy@news.albasani.net...

Internal oscillator at default 4 MHz.

Not enough room. Seriously.

--
Regards, Joerg

http://www.analogconsultants.com/

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Look again, da picture on page one. In particular at where the subtrate is connected to :-)

--
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I assume you mean "body"? Artistic license ?:-)

Did you note the split source? I've done that myself... handy.

...Jim Thompson

--
| James E.Thompson, P.E.                           |    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     |
             
 I love to cook with wine     Sometimes I even put it in the food

Thanks E, that is very interesting (sorry, I don't know your frist name).

Yep, stuff like this close to hot relays needs to be mask programmed for production, but I assume Microchip could do that for the usual (nowadays steep) fees. So testing with flash could be ok.

subsequently a false

sure

That's the concern. It may work several thousand times and then one fine day ... *KABLAM*

While it is no problem to devise my own SVS/POR/BOR (I often do that anyhow because I have learned not to trust many commercial products on this) there needs to be some guarantee by the mfg such as "If you hold RST down for xx microseconds after VCC is above x.x volts it'll be all peaches". That would need to be in the datasheet or some other released document.

running, or erratically

The extermal BOR could pull it into reset and hold it there until it's down to about a volt.

--
Regards, Joerg

http://www.analogconsultants.com/

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Yes, body.

Hey, don't skedaddle over to another topic here, the body connection _is_ wrong. So, I guess your amateur remark was a bit uncalled for :-)

I am not such a fan of split source. Neither of using Rdson to measure currents. The process tolerances are too large, I like to have my own sense resistors so I can push the inductances a bit harder without white knuckles.

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I'm kind of curious as to the type of solenoid coil you're using?

The timing spec's you are spitting out seems a little fast for a conventional coil? I would think the induction in the coil wouldn't allow the response times you are dealing with?

Care to tell us the H value of the coil?

That's an interesting MosFet, Kind of gives me some idea's for it's use in a project, accept with a higher (A) rating.. Interesting internal current limiting circuit. Even the Vgs(t) looks inviting! :)

Does save on part count.

Not much is known at this point but the trick with this kind of stuff is always the same: Design a coil that is rated for a small fraction of the applied voltage. Then apply the full brunt until it reaches nominal current, throttle back, leave it there until the relay contact has leaned into its desired position, ramp down to hold. That's what many chips can do but they are usually too wimpy, lossy, and large. CMOS versions are more enticing but usually too low in rated voltage.

--
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We used a simple audio class D amp chip to drive one of our designs once. A simple mono amp from Fry's comes to mind.

Otherwise FETs or IGBTs

:Need to drive a >30V (several amps) coil but back off once it's on to :avoid a cook-out. This needs to be PWM'd because the drive electronics :can't get hot at all. So I looked at coil driver chips. DRV103 and the :like. Many can't stomach more than 32V which is borderline for me and :the saturation voltage respectively Rdson values, well, yawn. Nothing to :write home about. : :Did I miss a really good chip? Else I'll just roll my own.

Have you considered the Ericsson range of drivers? eg. PBD354x/1

(source) (sink)

Joerg, I suggest you look at IR's IRS2153 or 21531 self-oscillating high-voltage half-bridge ICs. These generate their own low-voltage supply from the coil supply, and they have a 555-like oscillator that you can easily trick into continuous on or off states, besides PWM.

Win