I am reading the BAV99 datasheet from ON Semiconductor.

From the table on ELECTRICAL CHARACTERISTICS (page 2)

(TA = 25°C unless otherwise noted) (Each Diode)

Forward Voltage mVdc
IF = 1 mAdc 715mV
IF = 10 mAdc 855mV
IF = 50 mAdc 1.0V
IF = 150 mAdc 1.25V

On page 3 there is the following VI curve graph:

BAV99 VI curve

Clearly at 25°C - 100mA is Vf = 0.9V.

There is huge difference between the table and the IV curve.

  • Which source of information I should trust?
  • Is this (typical) and (maximum) where the table guarantees the diode won't exceed Vf 1.0v at 50mA while the graph is just typical values?
  • 1
    \$\begingroup\$ you have to design your circuit so that it works over the entire range of values, which change with current load, temparature (itself influenced by both V and I load!!) and random part-to-part variation. The range of load and temperature you wish to cover is up to you. \$\endgroup\$ – Pete W Jan 25 at 15:11

The table has the max values for the Vf with that current, it's saying it will not be more than that value. The graph is probably showing a the average value you'll see, but some parts will be above or below that.

As for which value you use, it makes sense to account for what would be worst case for your design, if you're concerned about power dissipation, then taking the max Vf for a given If makes sense.

  • \$\begingroup\$ its used to power a 3V3 regulator with USB if external power supply 5v was not available muxing (~4.5V from USB) with (5V0 power rail). the regulator it self has high drop voltage. the diode is not correct for the application but i don't want to introduce new BOM component in the circuit .. apparently i will change the regulator to low drop one .. \$\endgroup\$ – Hasan alattar Jan 25 at 13:06

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