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Voltage drop question using one series resistor

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enrico

enrico

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Dear All,

Is there anybody who can provide me an explanation why is not recommended to place only a series resistor when I want to connect a voltage regulator with 3.3 Volts and reduce the voltage up to another component to 2.8 Volts ?

People just say I shall use a voltage divisor instead, because only a series resistor would consume a lot of current I can burn the component. The component is an IC that works with 2.8 Volts and consume only 50uA.

If true, how to understand that only one resistor is not possible, since the R = 3.3 V - 2.8 V / 50 uA

Please advice.
 

I am not quite sure what you are planning. If you want to reduce a voltage from 3.3V to 2.8V with a single resistor, what value do you choose? If the current you require is fixed, that will be possible, but if it might vary, so will the 2.8V.

Keith
 

It is not convenient because with varying consumption of the 2.8V powered device, its supply voltage would vary too.

Better use a 0.5Vf drop diode in series instead of the resistor. Some schottkys are 0.5V

+3.3V-----------|>|-----------+2.8V
 

    enrico

    enrico

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