5

UC19431

UC29431

UC39431

UC39431B

Optocoupler Application

The two amplifier circuit architecture employed in the

UC39431 is most advantageous for the optocoupler ap-

plication. The error amplifier provides a fixed open loop

gain that is available to apply flexible loop compensation

of either poles or zeroes. A fixed transconductance am-

plifier provides a linear current source compared to the

typical transistor’s exponential output characteristics. It

also eliminates the traditional optocoupler’s CTR varia-

tions with power supply and voltage, and the need to

suffer the additional voltage drop of a series resistor.

Magnetic Amplifier Controller Application

The UC39431 makes an excellent controller for magnetic

amplifier regulated outputs. Working from either a square

wave drive or from a PWM signal controlled by another

output, a saturable reactor provides highly efficient con-

trol, requiring only a reset current which can be gener-

ated from its own output.

APPLICATION INFORMATION (cont.)

Figure 3. Magnetic amplifier controller application.

UDG-95090