The TPS53129 is a dual, adaptive on-time D-CAP2TM mode synchronous buck controller. The TPS53129 enables system designers to complete the suite of various end equipment's power bus regulators with cost effective, low component count, and low standby current solution. The main control loop for the TPS53129 uses the D-CAP2TM mode control which provides a very fast transient response with no external components. The TPS53129 also has a circuit that enables the device to adapt to both low equivalent series resistance (ESR) output capacitors such as POSCAP or SP-CAP, and ultra-low ESR, ceramic capacitors. The fixed frequency emulated adaptive on-time control supports seamless operation between PWM mode at heavy load condition and reduced frequency operation at light load for high efficiency down to milliampere range.The device provides convenient and efficient operation with input voltages from 4.5 V to 24 V and output voltages from 0.76 V to 5.5 V.