New from Torex Semiconductor the XC9246/XC9247 series is a non-synchronous step-down DC/DC Converter with internal LDMOS N-ch driver. It incorporates an integral bootstrap step-up circuit and the Lx and gate of the N-ch driver operate in phase to reduce high-frequency noise normally associated with older P-ch models.
Operating from input voltages as low as 4.5V up to 16.0V, the XC9246/47 is a versatile DC/DC converter IC aimed at cost sensitive applications. The output voltage can adjusted externally between 1.2V and VIN using two external resistors and output currents up to 1.0A can be achieved with a simple circuit. The XC9246 operates with fixed frequency PWM control whereas the XC9247 has automatic PWM/PFM switching control providing fast response, low ripple and high efficiency over the full range of load conditions.
The XC9246/47 series will be forced to stop operating by various protection circuits, such as a thermal shutdown circuit when the chip’s temperature reaches 150ºC and a UVLO (Under Voltage Lock Out) circuit when the input voltage decreases below a predetermined level set at either 4.0V or 6.3V. Both of the above functions are implemented using hysteresis, and will allow the XC9246/47 to resume normal operation when the chip’s temperature drops below 130ºC and when the input voltage increases to 4.2V or 6.5V respectively.
In addition to these protections, the XC9246/47 comprises a current limiter that monitors the coil current and not only stops the IC when the output current is too high, but if the over current state continues for 1.2ms (typ.) a latch function keeps the driver Transistor OFF until released by EN restart.
Others features of the XC9246/67 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 1ms and an external CR can be connected to extend the time as desired.
The XC9246/47 is available in USP-6C package for applications that require both a small form factor and a good amount of power dissipation, in SOT-26W package for handling even higher power dissipations. Additionally fully populated EVB can be provided upon request.