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Torex Semiconductor Launches the XC9273 Series of 5.5V Synchronous Step‐down DC/DC Converters

Published: Feb 21,2017

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Torex Semiconductor has launched the XC9273 series of 5.5V synchronous step‐down DC/DC converters featuring Torex’s unique HiSAT‐COT fast transient response control.

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The XC9273 is a feature rich Step‐Down DC/DC Converter that utilises Hi‐SAT COT, Torex’s own ‘Constant

On‐Time’ architecture, to deliver extremely fast transient response performance and high efficiency.

With Hi‐SAT COT the XC9273 only needs one low cost 47μF ceramic capacitor at the output side, whilst competitors often need multiple capacitors to achieve similar levels of performance. Hi‐SAT COT also provides less fluctuation in oscillation frequency against load and input voltage when compared to traditional COT control architectures. Adding extra capacitance at the output will allow the user to reduce output ripple further if required

With a 0.6V ±1.0% reference voltage source the output voltage can be set freely from 0.8V using external resistors. Furthermore, it is possible to control the output voltage dynamically using an external digital‐to‐ analog converter (DAC). Users can choose either a 1.2MHz or 3.0MHz switching frequency and output currently up to 3.0A are possible from an input Voltage range of 2.7V ~ 5.5V. Selecting the 3.0MHz internal switching frequency also allows the user to choose a smaller external Coil for space sensitive applications.

The XC9273 also allows the engineer to select different features using the MODE pins. Using a High or Low signal the engineer can select PWM control or PWM/PFM auto switching control (MODE1), Short Protection with latch or hiccup mode (MODE2) and optional CL discharge with soft OFF (MODE3). The integral soft start time can be adjusted with an external capacitor (CSS) and a Power Good feature is also included to help with system power‐up sequencing.

The XC9273 series will be forced to stop operating by additional protection circuits, such as a thermal shutdown circuit when the chip’s temperature reaches 150˚C and a UVLO (Under Voltage Lock Out) circuit when the input voltage decreases below 2.4V. Both of the above functions are implemented using hysteresis, and will allow the XC9273 to resume normal operation when the chip’s temperature drops below

120˚C and when the input voltage increases to 2.5V respectively.

Samples are now readily available in the QFN0404‐24C package measuring 4.0 x 4.0 x h0.75mm and Torex can also provide fully populated EVB upon request. The operating temperature range is ‐40OC to +105OC making the XC9273 the ideal choice for more demanding Point of Load applications where higher currents and fast transient response are required.

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