Programmable Buck Converter Helps Shrink Device Size

Programmable Buck Converter Helps Shrink Device Size

Diodes Inc.’s AP3440, a PWM synchronous buck dc-dc converter for low-voltage, high-density power systems, features programmable switching frequency between 200 kHz and 2 MHz. The converter reduces the size of external inductors and capacitors and simplifies overall power-supply design, according to the company.

A timing resistor sets operating frequency, which is easily synchronized with an external system clock applied to the same resistor input pin.  A 2.95- to 5.5-V supply voltage range suits the device for 3.3- and 5-V bus systems.

The AP3440 integrates a pair of low on-resistance, N-channel power MOSFETs, and can drive a 4-A load at efficiencies as high as 94%. Built-in protection features include overcurrent, overvoltage, thermal shutdown, and a programmable undervoltage lockout (UVLO) function.  The UVLO level is internally set at 2.6 V, but can be increased by programming the threshold using a resistor divider network on the enable pin.

To help minimize inrush currents and support power-up sequencing, the AP3440 also integrates a soft-start function, programmed via an external capacitor. 


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