AwaXe_v2dot5 (Athena Warm Asic for the X-ifu Electronics - version 2.5) is an upgrade ASIC developed for the Warm Front End Electronics (WFEE) of the future X-ray space telescope ATHENA. This 2.5 version integrates an ultra-low gain-drift LNA (Low Noise Amplifier), a buffer and 8 configurable current sources developed for a breadboard version (Phase A) of the X-IFU (X-ray Integral Field Unit) readout chaine - ATHENA space observatory. This ASIC also includes series bus RS485/I2C for slow control using RadHard by Design digital library and a differential thermometer for high common-mode noise rejection HK (HouseKeepig and Telemetry). This ASIC is one of the AwaXe and SQmux ASIC families developed at APC for the SQUID/TES readout. This development is funded by CNES and CNRS. This chip is developed to demonstrate the readout of one cryogenic multiplexer (Frequency domain SQUID multiplexer in the 1-6 MHz) for the X-IFU instrument.