GENERAL DESCRIPTION
    AX3131 consists of step-down switching regulator with PWM control. These devise include a reference voltage source, oscillation circuit, error amplifier, internal PMOS and etc.
    AX3131 provides low-ripple power, high efficiency, and excellent transient
characteristics. The PWM control circuit is able to the duty ratio linearly form 0 up to 100%. The converter frequency can be set by outside resistance. The wide range is from 200K to 1.3MHz. AX3131 is build out soft start function that prevent inrush current and overshooting. A shutdown switch, over current protect and short circuit protect functions are built inside, and when SCP happens, the operation frequency will be reduced to 150K. Also, an external compensation block is built in to good stable system.
    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 with exposed pad 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：4.5V to 23V
- Output voltage：VFB to VCC
- Duty ratio：0% to 100% PWM control
- Oscillation frequency：200K~1.3MHz (Outside resistance setting)
- Current Limit (CL), Short Current Protection (SCP)
- External Soft-Start function and Shutdown Function.
- Thermal Shutdown function.
- Built-in internal SW P-channel MOS.
- SOP-8L with exposed pad Pb-Free package.