analog input protection

[z0tya]

Is it possible to use this (max 366) for saving vems analog input pin against overvoltage?
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1084

[SamSpade]

Short answer is no.

For resistive sensors like CLT thermistors and TPS, it will give a totally wrong reading since the chip introduces a resistance in series.  For active sensors like MAP sensors, the chip will clamp the output above GND and to just 3.5V (+5V - 1.5V).  Most MAP sensors (and VEMS) use the full range of 0-5V for the pressure values.

Which inputs did you want protected anyway?

[rob@vems.co.uk]

I'm guessing he means the ALS/Launch inputs.

[Denmark]

Does it matter, if All that The switch is conneted to is Ground, you only need protection if you plan to run something other then a grounded swith

/Skassa

[z0tya]

for example vr sensor for wheelspeed

[rob@vems.co.uk]

That would need something like a LM1815 chip and some pull-down resistors.

[SamSpade]

Yes, the LM1815 Adaptive Variable Reluctance Sensor Amplifier is the proper way of interfacing with a wheel speed sensor, the same way VEMS does it.  In fact you can use the 2nd LM1815 (U12) on the board if you had it installed but don't use it for camsync.

[z0tya]

Yes, the LM1815 Adaptive Variable Reluctance Sensor Amplifier is the proper way of interfacing with a wheel speed sensor, the same way VEMS does it.  In fact you can use the 2nd LM1815 (U12) on the board if you had it installed but don't use it for camsync.

Wow it's a great idea, my vems config is vr/vr and i run wastedspark now, so the 2nd chip is usable.
Can you write how can I use it? Maybe with pics

Thx

[SamSpade]

If you can take a high-res photo of your board I can figure out what changes (resistors, jumpers, etc.) you need to do.  Just need the part of the larger yellow box below.  The 2 LM1815 are the ones boxed.  The lower box are the jumpers.  We may have different jumper settings so it's best we see how yours is set up.

[z0tya]

Thanks!

This the best photo what I have now. Maybe good...
http://www.cosworth.hu/misc/myvems_top.jpg