350 micro ohm resistor for shunt current sensing

[madusanka]

hi to all,

i need 350micro-ohm shunt resistor for current sensing in ADE7757 ic, but i couldn't find this resistor in the market. i search few electronic supplies companies bt they dnt have this resistor.. any one have idea about this problem .can i use another resistor instead of this ?:-(

plz reply me soon.

thanx,

 

[Tahmid]

Hi,
This is an uncommon value. A more common value is 1 mohm(0.001 ohm). If the current sensing doesn't need to be absolutely precise, you could parallel 1 mohm (0.001 ohm) to obtain a resistance of 333 uohm.

You can find 350 micro ohm resistor here: WSMS5515L3500JK Vishay/Dale Résistances détection de courant - CMS

Hope this helps.
Tahmid.

 

[FvM]

Of course, you don't need exactly 350 µOhm for the energy measurement chip, they have programmable amplifiers and full scale scalibration, and you can place a voltage divider, if you prefer hardware adjustment. You have to keep the input voltage of the current measurement channel, and I guess, you want to limit the power dissipation. But a certain resistor range would be still possible. 300 and 500 µOhm are however quite common values for low ohmic resistors. For large AC currents, a current transformer or di/dt (rogowski) sensor would be preferable in my opinion anyway.

 

[chuckey]

For current sensing with a resistor of this value you will need a four terminal device.
Frank