Voltage References and Ohm Law

[engr_joni_ee]

Hi,

I have a very basic question on circuit theory. If I connect the output of Voltage Reference 3.3 V ADR4533 (high precision and low noise is required for some application) to two resistors (100 Ohm each) in series, the second resistor is connected to ground. This is a simple voltage divider configuration. According to the data sheet of ADR4533, the maximum output current is 10 mA.

Ohm Law says if 10 mA flows through two 100 ohm resistors in series then the voltage drop across each would be 10 mA x 100 ohm = 1 V and the total voltage across both resistors would be 2 V then how 3.3 V is maintained using ADR4533 ?

 

[dick_freebird]

You are exceeding that datasheet limit and some specs may
no longer apply (such as, output accuracy). The VOUT may
not be maintained, or only under some other limited conditions
(higher min VIN, max temp, expected service life, etc.).

If you want a regulator, then use a regulator.

 

[engr_joni_ee]

What about if I use Voltage Reference with at least 20 mA current ?

 

[KlausST]

Hi,

May I ask why you insist on 100 Ohms?

Klaus

 

[engr_joni_ee]

This is a requirement of load which has two 100 ohm resistors. They have to be powered up by 3.3 V. I just wanted to know whether it is ok to use 3.3 V Voltage Reference ADR4533 or not ?

 

[KlausST]

Hi,

You are aware of Ohm's law.

So it should be no problem for you to calculate the current of two 100 Ohm resistors in series at 3.3V

Klaus

 

[schmitt trigger]

Either you use a higher rated reference or you use a buffer amp.