600mA Synchronous Rectification Step-Down DC/DC Converters—XC9235/9236/9237 Series

The XC9235/9236/9237 series are DC/DC converters with synchronous rectification characteristics, built-in P-ch drivers with an on-resistance of 0.42Ω and N-ch drivers with an on-resistance of 0.52Ω, and are compatible with ceramic capacitors. Only one coil and two capacitors are used externally to achieve high efficiency and a stable output current of 600mA. The operating voltage range is from 2.0V to 6.0V. The output voltage is internally set, and the interval of 50mV is selected within the range of 0.8V to 4.0V (accuracy: ±2.0%). The built-in clock controller has two types of 1.2MHz and 3.0MHz, and the appropriate operating frequency can be selected according to the specific application. The XC9235 series works in fixed PWM mode, the XC9236 series works in PWM/PFM automatic switching mode, and the XC9237 series can select fixed PWM mode or PWM/PFM automatic switching mode through an external control signal. The chip features high-speed load response, low ripple, and high conversion efficiency over the entire load range (from light load to high load current).

Built-in soft start and current limiting protection circuit. Using the standby function, the chip stops working and the current consumption can be reduced to 1.0μA or lower. With the built-in UVLO (undervoltage lockout) function, when the input voltage is as low as 1.4V, the internal P-ch driver is turned off.

The XC9235B/F/G, XC9236B/F/G, and XC9237B/F/G series have an internally set soft-start time of 0.25ms (TYP), so they can start up quickly in a very short time.

XC9235B/C/D/E/F/G, XC9236B/C/D/E/F/G, XC9237B/C/D/E/F/G have an internal self-discharge function for the load capacitor CL, which can release the charge on the load capacitor through the automatic discharge switch between the LX and VSS pins. When the device enters standby mode, the output voltage can quickly return to the VSS level through this function.

Two packages are available: SOT-25 (A/B/C series) and USP-6C.

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