The APE3520/A is a cost effective, dual-synchronous buck controller targeted for notebook system power supply solutions. It provides 5V and 3.3V LDOs and requires few external components. The 270kHz CLK output (APE3520) can be used to drive an external charge pump which is generating gate drive voltage for the load switches without reducing the main converter’s efficiency.

A constant on-time PWM control scheme operates without sense resistor and provides 100ns response
to load transients while maintaining a relatively constant switching.
The ultrasonic mode enables low acoustic noise at much higher efficiency than forced-PWM operation.
The APE3520/A includes power-up sequencing, the power-good output, internal soft-start and internal
soft-stop output that prevents negative voltages on shutdown.
The APE3520/A is available in a 24-pin QFN package and is specified from -40°C to 85°C ambient temperature range.

FEATURES
Wide Input Range: 6.5V to 28V
Output Range: 2V to 5.5V
Integrate 100mA 5V/3.3V LDO with Switches
Built-in 2V Reference Output (1% Accuracy)
4500ppm/°C RDS-ON Current Sense Compensation
With/Without Ultrasonic Mode Selectable and
Forced-PWM Operation
Low-Side RDS-ON Current Sense
Positive and Negative Current limit
Integrated OV/UV and Thermal Shutdown Protections
Integrated Boost Diode
Power Good (PGOOD) Signal
1.6ms Soft Start and Output Discharge Function (Soft-stop)