XC9252 Series

30V Operation Low Quiescent Current Step-down DC/DC Controller IC

The XC9252 series is a 30V operation step-down DC/DC controller IC. The external P-ch driver transistor is used to achieve a stable operation under low input voltage. Low ESR capacitors such as ceramic capacitors can be used for the load capacitor (CL).

A 0.8V reference voltage source is incorporated, and the output voltage can be set freely from 1.0V using external resistors (RFB1, RFB2).

300kHz to 600kHz can be selected for the switching frequency by connecting an external resistor to the ROSC pin. The generation of unneeded noise can be reduced by this synchronization with an external CLK within ±25% of the internal clock using the MODE/SYNC pin. In automatic PWM/PFM control, the IC operates by PFM control when the load is light to achieve high efficiency over the full load range from light to heavy.

The soft start time can be set as desired by adding an external capacitance to the SS pin.

With the built-in UVLO function, the driver transistor is forced OFF when input voltage becomes 2.5V or lower.

Internal protection circuits include over current protection, short-circuit protection, and thermal shutdown circuits to enable safe use.

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Oct 17, 2013
Product News
【New Product Leaflet】XC9252 Series
Jun 5, 2013
Product News
105°C Step-Down DC/DC Controller with 30V Operation and Low Supply Current XC9252 Series


Input Voltage Range 3.0V~30V (AbsoluteMax Rating 36V)
FB Voltage 0.8V(±2%)
Quiescent Current 30μA(@300kHz)
Oscillation Frequency 280kHz~550kHz (External Resistor)
External Clocking Synchronous ±25% of the internal clock
Protection Circuits Over current limit
Integral latch method(XC9252C)
Automatic return(XC9252A/B)
Thermal shutdown
Capacitor Low ESR Capacitor
Operating Ambient Temperature -40℃~+105℃
Environmentally Friendly EU RoHS compliant, Pb free



Technical Document

Quality Reports


QuestionHow does the GO function of DC/DC converters work? Does it work just like a regulator?

Torex regard the PWM/PFM automatic switch control function as Green Operation (GO) in the case of DC/DC. The GO function is defined as the switching operation between the PFM mode for a small output current and the PWM mode for a large output current. The PFM control method controls the output current by increasing and decreasing the fall time according to the output current while keeping a pulse width. The PWM control method controls the output current by adjusting the pulse width of the rise time, which keeps the rise/fall time interval constant and increases the efficiency at a heavy load. By switching between the PFM control for a small output current and the PWM control for a large output current, the quiescent current can be controlled for both of heavy and light loads.

QuestionWhat is the soft-start function?

The function to soften the rise to prevent the inrush current.

QuestionWhat does the FB product mean?

An IC for which any output voltage can be set by the reference voltage of the FB pins and the external dividing resistor. The output voltage is determined by the RFB1 and RFB2 values, using the following formula: VOUT = Vref × (RFB1 + RFB2)/RFB2

QuestionHow does UVLO (under voltage lockout) work?

This circuit forcibly turns off the driver transistor when VIN drops below the UVLO voltage. If the input voltage recovers to the value which is equal to the specified value or more, UVLO will be released to resume the switching operation. It is resumed by the soft-start function. The paused state by UVLO is not the shutdown. The pulse output is stopped, but the internal circuit is operating.

QuestionWhat is PFM control and PWM control?

PFM control is a method to control the output current by maintaining a constant pulse width, and increasing and decreasing the OFF time according to the output current. Since the PWM control adjusts the pulse width of the ON time to control the output current, the cycle of the ON and OFF time becomes constant, which increases the efficiency during a heavy load. The current consumption during a heavy loading and light load is controlled by switching to PWM control when the output current is high, and to PFM control when the output current is low.