Amplifier of the ST7 FLITE05/09

[msteinhart]

Posted on July 06, 2004 at 08:38

Amplifier of the ST7 FLITE05/09

[msteinhart]

Posted on June 16, 2004 at 06:53

Hey there,

I'm trying to use the amplifier of the FLITE05. The range should be 0-250mV. But in this range I got a ADC Range from 9 - 113.

When I increase the voltage up to 500 mV, the ADC Value increase up to 200 which is the highest ADC result.

Where is the problem?

[marco32]

Posted on June 16, 2004 at 07:10

I've no experience with the ST7Flite, but i read the datasheet, and i noticed that the range 0-500mV only works if the Vdd is 5V.

[msteinhart]

Posted on June 16, 2004 at 08:15

My Vdd is 5,1V, but the range is in the data sheet from 0V - 250mV. (Chapter 11.4.3.2)

[anshul]

Posted on June 22, 2004 at 14:36

You are right the input voltage range when Vdd is 5 V is indeed from 0 - 250mV.

[anshul]

Posted on June 22, 2004 at 14:40

You are getting ADC range from 9-113 when the input voltage is from 0-250mV which is right.

Voutput = Voffset (200mV) + 8*250mV = 2.2V

Digital value = (2.2*256)/5 = 113

[nicolas_walczak]

Posted on July 06, 2004 at 05:15

I'm not sure to understand what the problem is, but I see on the note of the chapter 11.4.6 that the amplifier is not available on st7Lite05...

[wolfgang2399]

Posted on July 06, 2004 at 06:04

Hi Nico,

referring to the datasheet the OpAmp isn't available on ST7LITES5 but it is on ST7LITE05.

Regards

woro

[anshul]

Posted on July 06, 2004 at 08:38

If you refer page 1 of the datasheet, you would find that ST7Lite05 and ST7Lite09 both have 8-bit ADC with Op-Amp.