Buck regulator IC from Allegro MicroSystems

The high step-down ratio made possible by an ‘on’ time of less than 50 ns permits a wide output voltage range from 0.8 V to 15 V at 3 A from an input supply voltage range from 9 V to 46 V. Standby current is less than 100 microampere.

The device’s capability for high switching frequencies (up to 2 MHz) leads to the use of smaller and lower-value ancillary components such as inductors and capacitors, while the high level of integration means that a minimal number of external components are needed. As a result, the A4403 provides a compact, flexible and cost-effective solution for office automation, industrial and consumer applications.

Optimal drive circuits are utilised to minimise switching losses, and the switching frequency is maintained constant as the input voltage modulates the ‘on’ time. This feed-forward control ensures excellent line correction. An external resistor pulled up to the input supply programs the ‘on’ time.

When power is initially applied and the device is enabled, a user-configurable soft-start function is implemented to minimise inrush current and to prevent output overshoot. Internal housekeeping and bootstrap supplies are provided which only require the addition of one small ceramic capacitor. A top-off charge pump is also provided to ensure correct operation at light loads.

Internal diagnostics provide comprehensive protection against overcurrents, input undervoltages, and overtemperature conditions. The device is rated for an operating temperature range from -40ºC to +105ºC.

The A4403 is supplied in a 16-contact, 4 × 4 × 0.75 mm QFN package (suffix EU) with exposed pad for enhanced thermal dissipation. It is lead (Pb) free, with 100% matt tin lead-frame plating.