Current Loop

Posted on Dec 16, 2012

This 5-V circuit utilizes a servo-controlled dc/dc converter to generate the compliance voltage necessary for loop-

Current Loop
Click here to download the full size of the above Circuit.

current requirements. This circuit will drive 4 to 20 mA into loads as high as 2 200 with 44 V of compliance. It is inherently short-circuit protected. A current source by definition limits current regardless of the load. The circuit"s input voltage and the 4-mA trim network determine ICl"s positive input voltage. ICl"s output biases the LT1072 switching regulator"s Vc pin. The resistors connected to the regulator"s feedback pin, fb, prevent the circuit output from running away in the event that the load opens up. Normally, IC1 controls the loop. However, if the load opens, IC1 receives no feedback. Under this condition, the FB pin becomes active when it equals 1.2 V and forces the loop to close locally around the regulator by activating IC2"s internal amplifier. Thus, the circuit automatically changes from a current to a voltage regulator, thereby preventing excessive output voltages.

Leave Comment

characters left:

New Circuits



Popular Circuits

Low power temperature controller
Metal locator circuit
90Vrms voltage regulator
Sample and hold circuit II
mic circuit
300w Mosfet Linear Amplifier For 50 Mhz
Test-Measurement 4
Bus Description RS644 LVDS
One second Audible Clock Circuit Schematic
LED Dance Pad
Voltage differential negative feedback circuit
High pressure natural gas shutoff valve drive circuit diagram
By BH-SK-1 produced a single bond Touch light switch
CS51227 by the output of 28V 5A DC power supply circuit