GENERAL DESCRIPTION AX3503 is a high efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. The device is available in an adjustable version. Supply current with no load is 350uA and drops to <1uA in shutdown. The 2.5V to 6V input voltage range makes AX3503 ideally suited for single Li-Ion, two to four AA battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. PWM pulse skipping mode operation provides very low output ripple voltage for noise sensitive applications. Switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors. The internal synchronous switch increases efficiency and decreases need of an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. AX3503 is available in small SOT23-5L, TSOT23-5L and TDFN-8L (3*3) packages.
FEATURES - 2.5V to 6V Input Voltage Range - High Efficiency: Up to 96% - 1.5MHz Constant Frequency Operation - 1A Output Current at VIN=3.6V and VOUT=1.8V - Quiescent Current: 350uA (input < 4.2V) - No Schottky Diode Required - 100% Duty Cycle in Dropout - 0.6V Reference Allows Low Output Voltages - Current Mode Operation for Excellent Line and Load Transient Response - Current limit, Enable function - Short Circuit Protect (SCP) - ≤ 1μA Shutdown Current - SOT23-5L, TSOT23-5L and TDFN-8L (3*3) Pb-Free packages
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