Reading Figaro TGS2620 Solvent Vapors sensor

Marco Dassi

Part Number: LMP91000
Other Parts Discussed in Thread: ADS1100,

Hello,

I've to build a alcohol %vol meter using the Figaro TGS2620 sensor, but there's a problem: the cable from CPU board to the sensor can be 2 - 3 meters long. Having read that the sensor requires a very precise voltage (specs are 5.0V +/- 0.2V), I'm scared about voltage drops along the cable (not counting interferences etc), so I'm thinkin' about making a small PCB inside the sensor housing which contain the AFE and the ADC; this way, only power supply and I2C bus will be carried in the cable

Which solution do you think it's better for this PCB?

1. 5.00V regulator (using a LM4120 as voltage reference, buffered by a transistor) to power the sensor, heater and 16-bit ADC (ADS1100);

2. same as 1., but using a LMP91000. Will it work, anyway?

Any suggestion is welcome, component price is not a limit (finally!), but the system have to be very precise.

Thank you and best regards,

- marco

over 3 years ago

0 Marco Dassi over 3 years ago

Prodigy 200 points

Ok, sorry, I didn't notice that the LMP91000 is "only" a front end; the ADS1100 ADC is still required.

So, what's better for a long sensor cable:

1. a small PCB inside the probe with AFE and ADC;

2. a "4-wire-like" (RTD way) to measure the sensor resistance

Thanks again

0 Josh Wyatt over 3 years ago in reply to Marco Dassi

TI__Guru* 91086 points

Dear Marco -

I think your idea of using cable for I2C and power (alone) is better than putting sensor signals over a long cable.

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Reading Figaro TGS2620 Solvent Vapors sensor