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Widebands That You Would or Wouldn't Buy 
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LQFP112 - Up with the play

Joined: Fri Nov 29, 2013 12:10 am
Posts: 109
Here is the other side of the PCB.

Again, "part number for part number" the same as the LC-1. With a few exceptions.
Some of them are so old, I would be worried about an EOL notice.

I did a little poking around with the scope. I verified that they are using PWM for DAC now, with an opamp for output buffering.

The 5v rail is pretty noisy.


Unlike the LC-1, there is no MAX202/MAX232 for the serial outputs. So, I will check to see if they still conform. Or, are just +12v and ground, now.

The case is semi-sealed. There is a channel for o-ring cord around the perimeter. But, no seal at the joints. The strain reliefs are pretty solid.

I don't understand the mounting ears. They are not flush with the back of the housing. So, if you tighten them down, they may break off or bend. It looks like it is intended to be mounted on standoffs. Maybe there is a kit.

It LOOKS like the +12v power ( red wires ) goes directly to the sensor heater. This could be a problem if power is hooked up backwards. Power would flow through the MOSFET's freewheel diode? Although, with the simplified wiring, it is probably a lot less likely to happen on the LC-2, than before. The LC-1 has a big blocking diode in that circuit.

The CPU is the same as the LC-1. Except for the different DAC interfaces, I say it's 50/50 whether the LC-1 firmware could run on the LC-2 and vis-versa. I don't have time to to buzz it out.

This one goes back into the drawer until they release new sw/fw to fix the "instant mode" issue. I ordered a new PLX 3rd Gen unit to play with. Seems this is the year of the new wideband design.


Attachments:
inside2.jpg
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Mon Dec 09, 2013 3:28 am
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
Posts: 241
Location: Toronto Canada
Thanks again for the pictures.

The switching regulator is a huge mystery to me, the max peak load on the 5v rail will be under 100ma, typical would probably be in the range of 50ma. The serial connector is it a 4 wires? If it is 4 wires then my guess is that innovate is planning to offer expansion stuff for the LC2 which taps power from the LC2's switching regulator, if it is not 4 wire then I have no idea.

When you get the PLX unit, please take pictures of the PCB and post them up.

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Mon Dec 09, 2013 4:40 am
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
Posts: 241
Location: Toronto Canada
Hentai wrote:
Toalan any plans on making a wideband that can read even richer than .63 lambda?


For my normal line of lambda controllers probably not, if I will do it I will probably just do it for the open source SLC Free design. Bosch only specifies accuracy of 0.01 lambda at 0.68 and leaner, if I go richer then the burden is on me to ensure accuracy below 0.68, it might mean I have to specify that my controllers will only work with the sensors I sell and I have to test each sensor I sell with richer than 0.68 lab gas. For the open source SLC Free design, people will be more forgiving I hope and probably cool with stuff not being super accurate below 0.68.

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Mon Dec 09, 2013 4:59 am
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LQFP112 - Up with the play

Joined: Fri Nov 29, 2013 12:10 am
Posts: 109
The serial connectors are 4-wire. but, no connection to the 5v rail. One of them seems to have RX TX and 2 ground wires. The other one has RX TX 1 ground and one floating. This matches what is shown in the LM-2 manual. The floating wire seems to be the "*MTS Sense" wire which would be grounded by the 2nd ground wire of another device. ok, that makes sense.

So, the switcher remains a mystery. I would guess that there are some low value resistor dividers or some such to try to give better noise immunity, by keeping impedances low, somewhere.

The switcher is an LT1767 which is a really expensive 1.5A regulator. They must be expecting a high current draw because they use a 2.2uH inductor. According to the datasheet that means that it goes discontinuous at anything under ~750mA. Unless they WANT it to operate in discontinuous mode. Which is nuts. Unless I am missing something.


Tue Dec 10, 2013 2:27 am
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
Posts: 241
Location: Toronto Canada
Does the unit have a TVS diode on the 12v power input? If so can you make out the model? I suppose perhaps innovate is also targetting industrial customers running 24v power rails, so they need a high efficientcy switcher. If the TVS diode is near or below 24v then I am wrong, if it is above 24v then maybe I am correct.

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Tue Dec 10, 2013 3:27 am
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LQFP112 - Up with the play

Joined: Fri Nov 29, 2013 12:10 am
Posts: 109
I was thinking along the same lines. I was thinking 28v for aircraft use.

But, I am guessing, no. The LT1767 is only rated to 25v Vin. That would be an awfully thin margin @ 24v.
Plenty of modern switchers go to 36v or 40v.

I didn't see a TVS.

Plus, the heater looks like it is connected directly across the power lines via the MOSFET.
And.... from Bosch :

"Maximum system supply voltage Vbatt,max ≤ 16.5 V
Minimum frequency of heater voltage control ≥ 2 Hz
Note: the use of the sensor with 24V power systems is
not permissible except if a voltage converter system is used.
"

Maybe they are working on a dual-channel unit w/ a slave PCB that gets it's power from this one. Or, some other kind of "combo-device".
Dual-channel would be nice.


Tue Dec 10, 2013 8:37 am
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LQFP112 - Up with the play

Joined: Fri Nov 29, 2013 12:10 am
Posts: 109
Looks like.... If you have seen the PLX SM-AFR GEN2 PCB, you have seen the PLX SM-AFR GEN3 PCB.

They are identical. Must be a firmware update.

Waiting for the 3rd shoe to drop :)


Fri Dec 20, 2013 12:04 pm
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
Posts: 241
Location: Toronto Canada
Hi,

Can you take a pic of the gen 3? I thought I had a gen 2 but it might be a gen 1, I have to check when I get home.

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Fri Dec 20, 2013 11:56 pm
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LQFP112 - Up with the play

Joined: Fri Nov 29, 2013 12:10 am
Posts: 109
The GEN1 PLX is a 2-board design. With the sensor connector on the daughter board.


Attachments:
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PLX_GEN2.jpg [61.38 KiB]
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File comment: PLX GEN1
plx-gen1.jpg
plx-gen1.jpg [ 24.06 KiB | Viewed 3792 times ]
Sun Dec 22, 2013 6:18 am
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
Posts: 241
Location: Toronto Canada
I thought it was more than that, between gen 1 and gen 2 they upped their warranty from 6 months to a year, I expected gen 2 to be better designed in terms of protection and temperature rating.

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Sun Dec 22, 2013 7:19 am
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