GENERAL DESCRIPTION
    AX3109 consists of step-down switching regulator with PWM control. These
devise include a reference voltage source, oscillation circuit, error amplifier, internal
PMOS and etc.
    AX3109 provides low-ripple power, high efficiency, and excellent transient
characteristics. The PWM control circuit is able to very the duty ratio linearly form 0
up to 100%. This converter also contains an error amplifier circuit as well as a
soft-start circuit that prevents overshoot at startup. An enable function, an over
current protect function and short circuit protect function are built inside, and when
OCP or SCP happens, the operation frequency will be reduced. Also, an internal
compensation block is built in to minimum external component count.
    With the addition of an internal P-channel Power MOS, a coil, capacitors, and a
diode connected externally, these ICs can function as step-down switching regulators.They serve as ideal power supply units for portable devices when coupled with the SOP-8L package, providing such outstanding features as low current consumption.
Since this converter can accommodate an input voltage up to 23V, it is also suitable
for the operation via an AC adapter.

FEATURES
- Input voltage：4.0V to 23V
- Output voltage：0.8V to Vcc
- Duty ratio：0% to 100% PWM control
- Oscillation frequency：330KHz typ.
- Soft-start(SS), Current Limit(CL), Enable function.
- Thermal Shutdown function.
- Short Circuit Protect (SCP).
- Built-in internal SW P-channel MOS.
- PDIP-8L Pb-Free package.