We have some ADP160 1.8v regulators in a gps receiver design and were puzzled when the bare receiver boards were failing when tested outside. After extensive investigation it would appear that the ADP160 regulators shutdown under direct sunlight, and reduce their output level when partially shaded. Has anyone else any experience with this? Is it a fault with the devices? As these receivers are for animal tracking and are often only lightly coated in clear epoxy for protection this is clearly going to be a problem. I am sure there are other designs around the world incorporating these devices that may also be affected by this 'feature'.
Any help/advice would be appreciated.