The new XC9248 series from Torex is a synchronous step-down (buck) DC/DC converter with two integrated N-ch driver Transistors and bootstrap configuration. The input voltage range is 4.5V to 18V and the maximum output current is 2.2A. Using the internal 0.8V reference voltage, the output voltage can be set using two external resistors within a range of 1.0V to 12V.
The XC9248 utilises a fixed PWM control method for high efficiency which also generates low levels of output ripple.
The operation temperature range is -40 OC to +105OC making the XC9248 the ideal choice for more demanding applications. To save cost, inexpensive Ceramic Capacitors can be used at the output and the DC/DC’s internal 500kHz switching frequency means a small external Coil can be deployed.
The XC9248 includes Over Current and Lx short circuit protection and there is an integral VOUT short circuit protection circuit to prevent excessive inrush current. With the Over Current and VOUT short-circuit protection circuits the designer can select either a Latch or Auto-restart configuration depending on the application requirements.
The 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 3.8V. Both of the above functions are implemented using hysteresis, and will allow the XC9248 to resume normal operation when the chip’s temperature drops below 125°C and when the input voltage increases to 4.5V respectively.
Others features of the XC9248 series include a chip enable pin to turn the IC on and off, a CL discharge function to quickly discharge the output capacitor when the IC is turned off, and an integral soft-start circuit to help limits rush current and output voltage overshoot when starting. The soft start time is fixed internally at 2.8ms and an external CR can be connected to extend the time as desired.
The XC9248 is readily available in a SOP-8FD package measuring 6.0mm x 4.9mm x 1.55mm and the package incorporates an exposed GND tab to maximise heat dissipation.