The AP3503 is a 340kHz fixed frequency, current mode, PWM synchronous buck (step-down) DC-DC converter, capable of driving a 3A load with high efficiency, excellent line and load regulation. The device integrates N-channel power MOSFET switches with low on-resistance. Current mode control provides fast transient response and cycle-by-cycle current limit. The AP3503 employs complete protection to ensure system security. Including output Over Voltage Protection, input Under Voltage LockOut, programmable soft-start, Over Temperature Protection to safeguard the circuit. This IC is available in PSOP-8 package.