ST7LITE39 Impedance

[heiko239955_st]

Posted on June 12, 2007 at 05:58

ST7LITE39 Impedance

[heiko239955_st]

Posted on June 11, 2007 at 13:19

Hello!

Can somebody say to me, what's the typical

resistance/impedance of an input pin at

the ST7LITE39.

I've been connected the PIN and declared as

Floating-Input for the ADC (AIN3).

I want to divide the voltage with a second resistor and need the exact value.

Thank you.

Best Regards,

Heiko

[fggnrc]

Posted on June 12, 2007 at 04:22

The replay to your question is in the section 13.8.2 ''I/O Port Pin Characteristics'' of ST7FLITE39 datasheet.

Please, be informed that the input resistance is not linear owing to the input protection diodes.

In my opinion, to attenuate and feed an input signal to the ADC, it is better to attach the AIN3 pin to an external resistor series where flows a current of about 100uA so that the ADC leakage current (1uA) may be ignored.

BR

EtaPhi

[heiko239955_st]

Posted on June 12, 2007 at 05:58

Hi,

thank you for the reply.

I have been changed the configuration with the input divider

of the resistors. Now I'll use a external resistor.

I have been found the note in the users guide.

Now it works well ;-).

Regards,

Heiko