General Description
The APL431 is a 3-terminal adjustable voltage reference with specified thermal stability over applicable commercial temperature ranges. Output voltage may be set to any value between Vref (2.5 V) and 20 V with two external resistors (see Figure 2). When used with an photocoupler, the APL431 is an ideal voltage reference in isolated feedback circuits for 2.5V to 12V switching-mode power supplies. This device has a typical output impedance of 0.1Ω. Active output circuitry provides a very sharp turn-on characteristic, making the APL431 excellent replacements for zener diodes in many applications, including on-board regulation and adjustable power supplies.

Features
• Precise Reference Voltage to 2.500V
• Guaranteed 0.5%, 1% or 2% Reference Voltage Tolerance
• Sink Current Capability, 1mA to 100mA
• Quick Turn-on
• Adjustable Output Voltage, VO = Vref to 20V
• Low Operational Cathode Current, 250µA Typical
• 0.1Ω Typical Output Impedance
• SOT-23, SOT-23-5, SOT-89, SO-8, TO-92 and TO-92S Packages

Applications
• Linear Regulators
• Adjustable Power Supply
• Switching Power Supply