The basic principles of a new high-sensitive multi-element photosensor on the base of avalanche heterostructures with negative feedback (ANF) are considered. The main difference between such a structure and a conventional avalanche photodiode (APD) is non-stationarity of the electrical field strength in the avalanche region caused by the feedback. It is shown that when the non-stationarity is manifested at amplification of a single photocarrier, it changes radically the basic characteristics of the avalanche process. A qualitative physical model of ANF process as well as the results of numerical simulation and some experiments are presented. They show the sharp gain vs. voltage dependence that restricts manufacturing of multi-element APD is essentially smothered by the negative feedback influence. They also exhibit an ability of the ANF-based device to provide a unique, for a solid state photosensor, combination of low noise, high gain and low response time. Two types of the ANF devices -- MOS avalanche structure with pulse supplied voltage, and SiC-Si-based heterostructure with constant supplied voltage -- were realized experimentally. Both of them are shown to be easy in multi-element design manufacturing. The results illustrating the process of a few-photon light pulse registration by the SiC-Si ANF heterostructure are also presented. An opportunity of a new lead in the development of the high-sensitive multi-element photosensors on the base of the ANF technology is discussed.