Why have two resistors in parrallel

Thread Starter

Rocks45

Joined Jul 12, 2017
14
So i have two resistors on a IC's VCC pin connected to GND i dont think thats a voltage divider?or Is It?THe VCC pin is from a step down converter i cant figure it out.thanks
 

AlbertHall

Joined Jun 4, 2014
12,157
You might use two resistors in parallel to get a specific value not available as a standard value or because the power dissipation would be too great for one resistor but it seems unlikely that either of those would apply in the circumstances you describe.

Can you post the schematic for your circuit, please.
 

Thread Starter

Rocks45

Joined Jul 12, 2017
14
I dont have a schematic just from looking on a pcb.I guess my biggest question is why would you put that on the VCC pin that on average is using min. 250ma on the IC and running @ 3.3V. Iam looking at almost a watt of power over one resistor,even if i split it up iam still almost half a watt on the VCC pin.Just seems weird to me putting a resistor on the VCC pin for whatever reason.Or am i wrong?
 

dl324

Joined Mar 30, 2015
15,115
Just seems weird to me putting a resistor on the VCC pin for whatever reason.Or am i wrong?
It seems strange, but we have too little information to say one way or the other.

You have the board. Trace out and post a schematic for power circuitry from input to the VCC pin. Post the voltage before and after the resistor(s).
 
A couple of reasons come to mind:

The resistors are used elsewhere, so the # of different parts is less.
A part of the cost is due to the number of different components.
so, Two 1K resistors (500 ohms) instead of say a 470 ohm resistor. Adding a 470 ohm resistor increases the assembly time if that's the only one.
They needed a minimum load on the power supply so the PS would operate correctly.
1/Rt=1/R2+1/R2+....1/Rn

To increase power dissipation.

There are cases were three series resistors are not equivalent to the sum of the three resistors because of parasitics.
 

AnalogKid

Joined Aug 1, 2013
10,125
You've posted three times, and said that the power being dissipated is over 1/2 watt. How do you know this when
1. The IC part number is a secret.
2. The resistor value(s) are a secret.
3. The function of the circuit is a secret.
4. The power source is a secret.

ak
 

WBahn

Joined Mar 31, 2012
27,411
I dont have a schematic just from looking on a pcb.I guess my biggest question is why would you put that on the VCC pin that on average is using min. 250ma on the IC and running @ 3.3V. Iam looking at almost a watt of power over one resistor,even if i split it up iam still almost half a watt on the VCC pin.Just seems weird to me putting a resistor on the VCC pin for whatever reason.Or am i wrong?
So, reading between the lines because you don't seem to want to provide useful details, these two resistors 27 Ω each?

That's what would be required to have two in parallel draw a combined 250 mA from a 3.3 V supply.
 
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