XB431-LM

The XB431 is precision 1.24 V shunt regulators capable of adjustment to 30 V. Negative feedback from the cathode to the adjust pin controls the cathode voltage, much like a non- inverting op amp configuration (Refer to Symbol and Functional Diagrams). A two- resistor voltage divider terminated at the adjust pin controls the gain of a 1.24 V band- gap reference. Shorting the cathode to the adjust pin (voltage follower) provides a cathode voltage of a 1.24 V. The XB431 have respective initial tolerances of 1.5%, and functionally lend themselves to several applications that require zener diode type performance at low voltages. Applications include a 3V to 2.7V low drop- out regulator, an error amplifier in a 3V off- line switching regulator and even as a voltage detector. These parts are typically stable with capacitive loads greater than 10 nF and less than 50 pF.

Applications

• Shunt Regulator
• Series Regulator
• Current Source or Sink
• Voltage Monitor
• Error Amplifier
• 3- V Off- Line Switching Regulator
• Low Dropout N- Channel Series Regulator

Key features

• Low- Voltage Operation/Wide Adjust Range (1.24 V/30 V)
• Temperature Compensated for Industrial
• Low Operation Current (55μA)
• Low Output Impedance (0.25 Ω)
• Fast Turn- On Response