Programmable DC/DC converter reduces solution size

14th March 2014
Nat Bowers

The AP3440 is a PWM synchronous buck DC/DC converter suited for low-voltage, high-density power systems. Introduced by Diodes Incorporated, the converter's switching frequency is programmable from 0.2-2MHz, enabling a reduction in the size of external inductors and capacitors and simplification of power supply design.

The buck converter’s operating frequency is set using a timing resistor and is also easily synchronised with an external system clock applied to the same resistor input pin. A supply voltage range of 2.95-5.5V makes the AP3440 well suited for both 3.3 and 5V bus systems.

Packaged in the thermally enhanced V-QFN3030-16 package and integrating a pair of very low on-resistance N-channel power MOSFETs, the converter is capable of driving a 4A load at an efficiency level as high as 94%. The AP3440 ensures excellent line and load regulation, with its current mode control providing fast transient response and cycle-by-cycle current limit.

The buck converter’s built-in protection features include over-current and over-voltage protection, thermal shutdown, and a programmable under-voltage lockout (UVLO) function. The UVLO level is internally set at 2.6V, but is easily increased by programming the threshold using a resistor divider network on the enable pin.

To help minimise inrush currents and to support power-up sequencing, the AP3440 also integrates a soft-start function, programmed via an external capacitor. The inclusion of an open-drain ‘Power Good’ output signals that the device output is within 93% and 107% of its nominal voltage and helps to further reduce circuit footprint.

The AP3440 buck converter from Diodes Incorporated is available now, priced at $0.25 (USD) each in 10,000 unit quantities.

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