Lpc2000

Hi, Folks,

Does it still work if I apply a lower voltage to the Vref (2.5V) than 
the norminal VDD (3.3V) ?

Any ideas? 
Thanks 

Lei

The manual says, "This should be norminally the same voltage as Vdd but 
should be isolated to minimize noise and err"

Does it mean that it will not work correctly if I apply a voltage lower 
than Vdd ?

Thanks
Lei  
--- In lpc2000@yahoogroups.com, "fl429" <fl429@y...> wrote:

> Hi, Folks,
> 
> Does it still work if I apply a lower voltage to the Vref (2.5V) than 
> the norminal VDD (3.3V) ?
> 
> Any ideas? 
> Thanks 
> 
> Lei

Hello Lei,

The LPC2136 ADCs have their own power supply thru the Vdda and Vssa 
pins. As the datasheet specifies, you can go down to Vdda=2.5V and 
your ADCs will operate properly. However, keep in mind that the Vref 
level must not be higher than the Vdda, or your ADC will not yield 
correct results. 

The ADC operating conditions are: 
2.5V <= Vdda <= 3.6V and
2.0V <= Vref <= Vdda

The ADC chapter of the LPC2000 datasheets will be updated in future 
to reflect these details.

Regards,

Philips Apps Team



--- In lpc2000@yahoogroups.com, "fl429" <fl429@y...> wrote:
> The manual says, "This should be norminally the same voltage as 
Vdd but 
> should be isolated to minimize noise and err"
> 
> Does it mean that it will not work correctly if I apply a voltage 
lower 
> than Vdd ?
> 
> Thanks
> Lei  
> --- In lpc2000@yahoogroups.com, "fl429" <fl429@y...> wrote:
> > Hi, Folks,
> > 
> > Does it still work if I apply a lower voltage to the Vref (2.5V) 
than 

> > the norminal VDD (3.3V) ?
> > 
> > Any ideas? 
> > Thanks 
> > 
> > Lei

Thanks !
Lei
--- In lpc2000@yahoogroups.com, "philips_apps" <philips_apps@y...> 
wrote:
> Hello Lei,
> 
> The LPC2136 ADCs have their own power supply thru the Vdda and Vssa 
> pins. As the datasheet specifies, you can go down to Vdda=2.5V and 
> your ADCs will operate properly. However, keep in mind that the 
Vref 
> level must not be higher than the Vdda, or your ADC will not yield 
> correct results. 
> 
> The ADC operating conditions are: 
> 2.5V <= Vdda <= 3.6V and
> 2.0V <= Vref <= Vdda
> 
> The ADC chapter of the LPC2000 datasheets will be updated in future 
> to reflect these details.
> 
> Regards,
> 
> Philips Apps Team
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "fl429" <fl429@y...> wrote:
> > The manual says, "This should be norminally the same voltage as 
> Vdd but 
> > should be isolated to minimize noise and err"
> > 
> > Does it mean that it will not work correctly if I apply a voltage 
> lower 
> > than Vdd ?
> > 
> > Thanks
> > Lei  
> > --- In lpc2000@yahoogroups.com, "fl429" <fl429@y...> wrote:
> > > Hi, Folks,
> > > 
> > > Does it still work if I apply a lower voltage to the Vref 
(2.5V) 

> than 
> > > the norminal VDD (3.3V) ?
> > > 
> > > Any ideas? 
> > > Thanks 
> > > 
> > > Lei