GENERAL DESCRIPTION

AX3701 is a high efficiency monolithic synchronous buck regulator using a constant on-time (COT) architecture. The device is available in an adjustable version. Supply current with no load is about 30uA and drops to <1uA in shutdown. The 2.5V to 6.0V input voltage range makes AX3701 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. The constant on-time control scheme simplifies loop compensation and offers excellent load transient response. The high gain error amplifier in the control loop provides excellent load and line regulation. Proprietary adaptive on-time helps AX3701 to achieve nearly constant switching frequency across load range. AX3701 has cycle-by-cycle current limit and hiccup mode to protect over-load or short circuit fault conditions. 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. AX3701 is available in small SOT-23-5L, TDFN-6L (2*2) packages.

FEATURES

- 2.5V to 6.0V Input Voltage Range

- Output Voltage from 0.6V to VIN

- High Efficiency: Up to 92%

- 1.5MHz Switching Frequency Operation

- 1.2A Output Current

- Quiescent Current: 30uA (input < 4.2V)

- No Schottky Diode Required

- 100% Duty Cycle in Dropout

- 0.6V Reference Allows Low Output Voltages

- Internal 1msec Soft-Start

- Proprietary Fast Transient Constant On Time Architecture Stable with low ESR Ceramic Output Capacitors

- Cycle-by cycle Current limit Protection

- Hiccup Mode for Short Circuit and Over-Load Protect

- ≤ 1μA Shutdown Current

- SOT-23-5L, TDFN-6L (2*2)

- RoHS and Halogen free compliance.