Adjustable shunt regulator reduces standby dissipation

22nd April 2015

Siobhan O'Gorman

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An adjustable shunt regulator which features a 50μA minimum cathode current that is significantly lower than equivalent industry standard 431 devices has been introduced by Diodes Incorporated.This enables manufacturers of switch-mode power supplies to 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 characteris¬tics, a low temperature coefficient and low output impedance. The regulator 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 50μA. This key differentiator makes the device well suited as a Zener diode substitute in SMPS.

The output voltage of the 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. These packages are fully RoHS compliant and totally lead-, halogen- and antimony-free ‘green’ devices.

The AP431i low operating current shunt regulator also offers higher performance at a lower cost than competitive devices and is priced at $0.023 each and sold in 10,000-piece quantities.