XC9271 Series

30V Driver Transistor Built-in Step-Down DC/DC Converters

The XC9271 series are 30V operation step-down DC/DC converter ICs with an internal driver transistor. The internal Nch driver transistor is driven by bootstrap to achieve a stable, high-efficiency power supply up to an output current of 2.0A. Low ESR capacitors such as ceramic capacitors can be used for the load capacitor (CL).

A 0.8V reference voltage source is incorporated in the IC, and the output voltage can be set to a value from 1.2V to 12.0V using external resistors (RFB1, RFB2).

300kHz or 500kHz can be selected for the switching frequency. The generation of unneeded noise can be reduced by synchronization with an external CLK within the range ±25% of the internal clock using the 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 4.6V or lower.

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

Your news

Jun 2, 2014
Product News
30V, 2A Step-Down DC/DC Converter Operates to 105℃ XC9270/XC9271 Series
Apr 2, 2014
Product News
【New Product Leaflet】XC9270/XC9271

Typical Application Circuit


Input Voltage Range 7~30V
FB Voltage 0.8V(±2%)
Oscillation Frequency 300kHz,500kHz
Maximum Output Current: 2.0A
Control Methods PWM/PFM
Soft-Start Externally Set (set by external capacitor C)
Protection Circuits Over Current Protection 3.2A(TYP.)
Integral Latch Method(XC9271A)
Automatic Recovery(XC9271B)
Thermal Shut Down
Low ESR Capacitor Low ESR Ceramic
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 is the standby current?

The current that flows through the IC in the standby mode. The standby mode means the state where the IC has been turned off by the CE function.

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