Date: 14/01/2009

Valley current-mode control buck-type DC-DC converter

A4403 from Allegro is a new 3 A buck converter working on the principle of valley current-mode control. This control scheme allows very low switch on times to be achieved, making it ideal for applications that require high switching frequencies combined with high input voltages (9 V - 46 V) and low output voltages (0.8 V - 15 V). The right applications for this device are automation, industrial and consumer applications.

This device works at high switching frequencies of up to 2 MHz allowing smaller and lower value inductors and capacitors. The switching frequency is maintained constant, as the input voltage modulates the on-time. This feed-forward control ensures line correction. An external resistor pulled up to the input supply programs the on-time.

The other features of this device are,
1. User-configurable soft-start function to minimize inrush current
2. Internal housekeeping and bootstrap supplies are provided
3. A top-off charge pump is provided to ensure correct operation at light loads.
4. Protection features include over-current, under-voltages, and over-temperature.

Package: 4 mm × 4 mm, 0.75 mm QFN
RoHS compliant: Yes