Lpc2000

Ed see below

if you still have open questions I will do my best to answer them 

Robert


--- In lpc2000@yahoogroups.com, "edmiller613" <edmiller613@y...> wrote:
> 
> The LPC213x User Manual contains the following Note in Table 143:
> 
> "Note: if the A/D converter is used, signal levels on analog input 
> pins must not be above the level of V3A at any time. Otherwise, A/D 
> converter readings will be invalid."
> 
> Are you saying that the User Manual is wrong?
> 

In all devices with ADCs before the LPC2130 series, a signal >Vdd on
any pin "that could be used as analog input" screws up the ADC even if
it is defined as digital input. On the LPC2130 series the digital
input can now exceed Vdd. If the input is configured as analog input
you violate the spec (results in ADC wrong results) if exceeding Vdd.
Summary: if 5V on an analog input pin -> results corrupted, if 5V on a
pin that could be analog in but is configured as digital in -> no
corruption 

Confused?  Everything clear?


> 
> --- In lpc2000@yahoogroups.com, "philips_apps" <philips_apps@y...> 
> wrote:
> > 
> > First of all a happy and successful New Year to everybody!
> > 
> > There have been some questions about 5V tolerance of analog pins.
> > All device on the market before the LPC2130 series can not tolerate 
> 5V
> > on any pin that is configured or can be configured as analog input 
> pin.
> > Starting with the LPC2130 series, pins that are not configured as
> > analog inputs (but could be) will no longer have a negative effect 
> on
> > the ADC result. 
> > Please keep in mind that the pin 0.25 DAC output is not 5V tolerant
> > even  if used as digital I/O.  The effect will be that it starts
> > sinking current if not externally limited to the bitter end of 
> thermal
> > destruction. So at the very least limit the current if you expect 
> more
> > than Vdd on that pin.
> > 
> > Another question was there about 3.3V being up and running while 5V
> > are connected to some I/O pins. If you generate the 3.3V off the 5V
> > input using a voltage regulator, the delay will be short to have 
> 3.3V
> > after 5V, in fact it might actually be at 3.3V before the voltage
> > reaches 5V externally. The important issue is that during a longer
> > period of time with a pin externally driven up to 5V and no Vdd for
> > the microcontroller, there will be stress to the gate oxide and 
> sooner
> > or later the device will die. So, don't do that but do not worry 
> about
> > a 3.3V voltage generated from a 5V during power up. 
> > 
> > Hope I did not add to the confusion but answered to some of your 
> concerns.
> > 
> > Off to a good start, Robert