A4402: Constant On-Time Buck Converter With Integrated Linear Regulator

The A4402 is a dual-output regulator, combining in a single package a constant on-time buck regulator and a linear regulator (LDO)—each with adjustable output voltages. It is ideal for applications that require two regulated voltages, such as in microcontroller- or DSP-based applications requiring core and I/O voltage rails.

The buck regulator output supplies the adjustable linear regulator to reduce power dissipation and increase overall efficiency. The switching regulator is capable of operating above 2 MHz, allowing the use of small low value inductors and capacitors while avoiding sensitive EMI frequency bands such as AM radio in automotive applications.

Protection features include undervoltage lockout and thermal shutdown. In case of a shorted load, each regulator features overcurrent protection.

The device has an integrated power-on reset with adjustable delay to monitor LDO output voltage and provide a signal that can be used to reset a DSP or microcontroller. It also includes a watchdog circuit.

The A4402 is provided in a 16-pin TSSOP, with exposed pad for enhanced thermal dissipation. It is lead (Pb) free, with 100% matte tin leadframe plating.