Shorted capacitor

Hi, all…

Please help explain what is the purpose of 0 ohm resistor conneted in paralell with the capacitor. At first I thought the capacitor was shorted, I then realized it is not but the short comes from the 0 ohm resistor connected across it. I have attached the picture bellow.

1 Like

Hello moetimolateli,

A zero Ohm resistor is another name for a wire. This wire just happens to be in the form of a resistor. In this example, it is a surface mount form factor. These “wires” are easily installed using a pick and place machine.

In general, there are two purposes for the zero Ohm jumper:

  1. A form of hardwire programming. Various circuit options are enabled or disabled by removing the resistor. These options could be programming as when a microcontroller looks for a ground on a specific pin. They could also be physical as a particular part of a circuit may be enabled or disabled.

  2. A convenient method of routing a signal on a PCB. When the PCB artwork is being produced the designer will occasionally find a challenging wire run. The zero Ohm resistor allow the designer to fly over other wires thereby simplifying the PCB.

The MD5001T data sheet identifies pin 2 as the remote on/off control line. The standard diagram shows a switch with a bypass capacitor. My best guess is that the designer followed the common practice of integrating the reference design into the PCB. The jumper is used to permanently enable the device. The capacitor is along for the ride.



1 Like

Hi, APDahlen

Interesting staff, and well explained. Thank you.

1 Like