What is the maximum current I can force into the digital potentiometer?
The maximum current is limited by 2 boundaries at a given resistance setting.
1- Terminal voltage range limit
Its the dominant in most settings, in this case the voltage generates by the current and the selected resistance value cannot exceed the supply rails.
ie- Imax = Vdd / RWB
RWB = 5k
Vdd = 5V
Imax = 5V/5k = 1mA
2- Maximum current handling capabilities.
When the part is used in rheostat mode, at lower resistance values, the current is limited by the maximum current density.
This limitations depends on the frequency:
DC = maximum current density
AC (f > 10kHz) = maximum current density / pulse duty factor
AC (f < 10kHz) = maximum current density / sqrt (pulse duty factor)
ie. maximum current density = 3mA
signal frequency = 2kHz
duty = 50%
Imax = 3mA / sqrt(0.5) = 4.2mA
Typically data sheets include a Imax vs. Code graphs for DC current.
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