droput voltage versus load curve for part LP3878-ADJ

thank you, can you please let me know the Vin , Vout conditions under which this curve has been generated? regards Siddharth

The curve was generated from the Typical information in the LP3878-ADJ datasheet Electrical Characteristics table.

Slope = ΔVdo / ΔIout = 474mV / 799.9mA ≈ 592.574 µV / mA

Vout = 3.8V, this is nominal Vout

Vin = (Vout-100mV + Vdo) , or whatever is required to get Vout to drop 100mV from nominal Vout to 3.7V to force the dropout condition.

thanks can you please confirm the reason for dropping Vout by 100mV specifically in Vin = (Vout-100mV + Vdo 

It is describing the test method 'condition' used to ensure that the pass element is fully in dropout mode when it is measured.

Some datasheets call for Vout to drop some percentage from the nominal voltage, others set the input voltage to some defined value.

" ... if Dropout of Regulation is defined as when VOUT=2%VOUT? ..."

I don't see this condition listed in the LP3878-ADJ datasheet.

Not knowing the device where this condition is used, my answer could be out of context.

This condition would suggest that the Vin is lowered until Vout has fallen by 2% of it's original value, then Vin-Vout is measured.

So if the nominal Vout is 5.0V, the the input voltage would be lowered until the output voltage has fallen 100mV from the nominal value, if the nominal Vout is 3.3V the output voltage would be lowered by 66mV.

Keep in mind that this is the defined test condition. In actual use of the device 'Vdo' is the minimum Vin-Vout value where the pass element goes into saturation, active regulation of the output voltage ceases, and there is ANY perceptible drop in the output voltage. The Vin-Vout value that is measure with the output voltage dropped by 100mV is still considered valid if Vout has only dropped by 1mV.

Hi, can anyone help me with the voltage reference LT6656BIDC, i see in the datsheet block diagram back to back diodes connected on the input and output pins, can any one give some idea of their purpose and turn on voltage/current