Hi Christoph, I believe we were a little terse when we stated that it was 'not recommended'. Really we should say that it is not recommended under certain power supply configurations. The internal reference is typically 2.5V. So if we look at the recommend configuration table: Basically, what we are trying to convey is that the reference should be divided if your supply is lower than 5V. The switches in the DAC resistor ladder require some minimum supply headroom to operate. So if you have a lower supply, you require a lower reference voltage. For example, note that in the recommended operating conditions we show that with a 2.7V supply the reference can be at most (VDD-0.2)/2 or 1.25V if the divider is disabled. If the divider is enabled, then we can have a reference input of 2.5V. So there is some debate if having the resistor divider disabled by default is the best configuration, but it is safe if the VDD supply is 5V to 5.5V. I will also convey to the team that we should expand this explanation if we revise the PDS. thanks, Paul
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