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.

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Typical Application Circuit

Features

Packages

Package	SOP-8FD	Number of Pins	8
Pcs/Reel	1,000	Package Size(mm)	6.0 x 4.9 x 1.55
Package Dimensions [0.1MB] Taping Specifications [0.1MB] Package Power Dissipation [0.1MB] Perspective [0.1MB] Control Plan [0.1MB]

DATA SHEET

Technical Document

Quality Reports

FAQ

How 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.

What is the soft-start function?

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

What 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.

What 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 R_FB1 and R_FB2 values, using the following formula: V_OUT = Vref × (R_FB1 + R_FB2)/R_FB2