Low operating-current shunt regulator betters 431 specs, replaces Zeners

April 22, 2015 // By Graham Prophet
The AP431i adjustable shunt regulator, introduced by Diodes Incorporated, features a 50 μA minimum cathode current that is significantly lower than equivalent industry standard 431 devices.

Manufacturers of switch-mode power supplies can target applications that require very low power dissipation, particularly 12V/19V adaptors/chargers, but also TVs and monitors where standby power consumption is of great importance.

With reliable thermal stability over its full operating range, the AP431i three-terminal adjustable shunt regulator features fast turn-on characteristics, a low temperature coefficient and low output impedance. The AP431i has the same electrical specifications as a standard 431, while having an advantage in being able to regulate with a low minimum cathode current, typically 50 μA. This key differentiator makes it well suited as a Zener diode substitute in switch-mode power supplies.

The output voltage of AP431i can be set to any value between VREF (2.5V) and the corresponding maximum cathode voltage (36V). Two grades of initial voltage tolerance are offered, 0.5% and 1%, with three package options available: TO-92 (ammo-pack), SOT-23 and SOT-89.

The AP431i offers higher performance at a lower cost than competitive devices and is priced at $0.09 (10,000).

Diodes Inc. www.diodes.com