While the power supply circuit design is very important to keep the required specification, it is also important to keep the PCB area small.
Power circuit requires many passive components to achieve the performance and the space to lower the power integrity and thermal impacts.
Having the smaller components is always helpful and Torex semiconductor is the one of the key vendor that produces the small voltage regulators.
Their new devices, XCL223/XCL224 the synchronous buck “micro DC/DC” converter with integrated coil, are the ultra small size which dimension is 2.25mm x 1.5mm, and the height is 0.75mm. Yes, integrated coil.
Here is the quick summary in their product news page.
"Torex Semiconductor Ltd. (Tokyo Japan: President, Koji Shibamiya, 6616: 2nd section at Tokyo Stock Exchange) has launched mass production of the XCL223/224 Synchronous Buck “micro DC/DC” Converter with integrated coil. Minimum operating voltage is 2.5V & maximum operating temperature is 105°C.
The XCL223/XCL224 series are ultra-small (external dimensions: 2.25mm x 1.5mm x h0.75mm) step-down micro DC/DC converters with an integrated coil and control IC. These converters achieve the world’s smallest class of miniaturization and height reduction among output types with an output current of 0.4A / 0.7A."
Having the integrated coil is the value adder since the designer does not need to consider the vendor identifications for the external inductor.
The efficiency can be 80%-90% depending on the conditions and it supports HiSAT-COT which is an original Torex term for High Speed Transient Response.
The difference between XCL223 and XCL224 is either PWM control (XCL223) or PWM/PFM control (XCL224).
The typical application circuit described in the product page is very simple, just require the input and output capacitance as below.
The input and output voltage range is
The output current and oscillation frequency is
・Output Current：700mA(Type A)、400mA(Type B)
・Oscillation Frequency ：3.0MHz
I am not sure how the cost is like compared with the conventional step-down converter with the similar specification, but it might be worth it considering the other advantages like PCB space, test, external passive components, mechanical design, etc..
I would think it can be used for the CPU reference designs with the small form factor.
It does not seem like they have the any samples or boards that can be purchased online, unfortunately.
It would be fun to design voltage regulator evaluation boards or breakout boards using this part.