The XC9242 and XC9243 series of synchronous step-down DC/DC converters from Torex integrate one P-channel and one N-channel MOS power transistors and can be used with ceramic capacitors. The converters operate with input voltages ranging between 2.7 and 6.0V, and its output voltage can be set between 0.9V and VIN by using two external resistors. They are available with two different switching frequencies, namely, 1.2MHz for applications where high efficiency is critical, and 2.4MHz where space is crucial and when high speed line and load transient responses are required.
The DC/DC converters are forced to stop operating by protection circuits, such as a thermal shutdown circuit when the chip's temperature reaches 150ºC and an under-voltage lock out circuit when the input voltage decreases below 2.5V. Both the functions are implemented using hysteresis, and allow the converters to resume normal operation when the chip's temperature drops below 130ºC and when the input voltage increases to 2.68V. In addition to these protections, the converters comprise a current limiter that not only stops the IC when the output current is too high but also permits the IC to automatically resume normal operation as soon as the over-current condition disappears.
