MSP430F1121A: Internal Reference Issue at 3,3V

Alberto,

How are they measuring the VREF voltage without a VREF+ pin? Are they using precise and accurate measurement tools capable of uV? 0.47 to 0.5 V is only guaranteed for test conditions of 2.2/3 V, the customer needs to re-evaluate their devices using these voltages and ensure that the other test condition settings have been followed as well.

Regards,
Ryan

Ryan,

thanks for your feedback.
Can you kindly confirm and comment on the fact that Vref could be possibly higher at higher Vcc=3.3V?
Even if this is out of specs, do we have other cases / tests made at 3,3Vdc?

Thanks,
Alberto

There is no test data provided for 3.3 V, the customer will need to evaluate this themselves.

Regards,
Ryan

Ryan,

can we provide a rough extimation of expected shift?
For example, in case of 10% varioation of Vcc (3 to 3,3V) can customers expect 10% of Vref variation?

thanks and regards,
Alberto

Ryan,

can you kindly clarify your statement? You mention 0,52V, where the value in DS is in ratio Voltage / Vcc. So do you mean 0,52Volt or 0,52 as pure number?

thanks,

Alberto

Alberto,

I meant the latter (ratio), sorry for the confusion.

Regards,
Ryan

Ryan,
thanks for the clarification.
Said this, customer is asking me to provide summarization as following:

They are using signal “V(Ref050)” as described in datasheet where typical value of this “V(Ref050)” is 48% of power supply (in case of 3.0V power supply it is 1.44V). In their case (3.3V power supply) they saw reaction around 1.68V and this value is projection of cca 51% of 3.3V power supply.

To rewrite my question, what I need to know is:

1. Where is threshold (percentage from supply voltage or volts) for “V(Ref050)” in case of 3.3V power supply
2. How big is the tolerance range for “V(Ref050)” – you alredy informed that 52% is maximum but where is minimum?
3. Are values mentioned above guaranteed by design and all parts that they will use will fit (simply said they need to perform tolerance analysis and need data)?

thanks and regards,
Alberto

Alberto,

All information available has been provided, estimated tolerances are not guaranteed since they are not stated in the datasheet as tested specifications. Any further investigation will require input from the Design Team but I am not sure that they have worked on this test data either.

Regards,
Ryan