Atomic clocks provide enhanced accuracy, stability, and timing precision compared to quartz-based technologies. However, the size and power consumption of existing atomic clocks far exceeds that those of quartz-based clocks, not preventing their deployment in portable applications.The goal of the MAC-TFC proposal is to develop and demonstrate all the necessary technology to achieve an ultra-miniaturised, low-power an ultra-miniaturised caesium atomic clock, presenting a short-term stability of 5x10-11 over 1 hour while operating on the power of an AA battery, with less than 200 mW power consumption.Phased technology development approaches are planned. The first phase focuses on establishing theoretical limits of MEMS atomic clocks and demonstrating practical design and fabrication feasibilities, optimizing the performances of atomic resonator. Then, the second phase of proposal aims at demonstrating and developing the technologies of the building blocks for the miniaturized clock including a fully customised semiconductor laser, an innovative approach of filing the clock cell with alkali vapour and a low-power ASIC for the analog Radio Frequency (RF) electronics. The third phase is concentrated on the final chip-level integration and package of two alternative prototypes of MEMS atomic clock using LTCC technology. The physics package includes a micromachined cell with well controlled alkali vapour, a semiconductor laser , collimatting/polarizing microoptical elements and a photodetector. Finally, a fourth phase is devoted to the testing the final assembly of the physics package together with the developed electronics, as well as setting the basis for technology transfer and pre-industrialisation for potential applications.To this aim, MAC-TFC brings together a consortium made of 4 major academic institutions (UFC, UniNE, WUT, UUlm), 2 research institutes ( VTT, CEA) and 3 industrial partners, SAES, ASU, OSA.