XC9250 Series

Technical Document
General Description
Your news
Typical Application Circuit
Features
Packages
FAQ
Quality Reports
Part numbers
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30V Driver Transistor Built-In Step-Down DC/DC Converters

The XC9250 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 suppressed by synchronizing to an external CLK in a range of ±25% of the free running frequency 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 4.5V 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 27, 2013	Product News	30V, 2A Step-Down DC/DC Converter Operates to 105℃ XC9250/XC9251 Series

Typical Application Circuit

Features

Input Voltage Range	7V～30V
FB Voltage	0.8V±2%
Oscillation Frequency	300kHz 500kHz
Maximum Output Current	2.0A
Control Methods	PWMControl
Soft-Start	External Capacitor (set by external capacitor C)
Protection Circuits	Over Current Protection 3.2A(TYP.) Integral Latch Method(XC9250A) Automatic return(XC9250B) Thermal Shut Down
Low ESR Ceramic Capacitor	Ceramic Capacitor
Operating Ambient Temperature	-40℃~+105℃
Environmentally Friendly	EU RoHS compliant, Pb free

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]

FAQ

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
How does UVLO (under voltage lockout) work?: This circuit forcibly turns off the driver transistor when V_IN 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.
What 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.