XC9247 Series

16V Driver Transistor Built-In Step-Down DC/DC Converters

XC9247 series is a 16V step-down DC/DC converter with a built-in driver transistor. The series provides high efficiency, and a stable power supply with output currents up to 1A. The series is designed for use with small ceramic capacitors.

The series has a 1.0V reference voltage, and using externally connected resistors, the output voltage can be set freely. With an internal switching frequency of 1.2MHz, small external components can be used. The soft-start time is internally set to 1.5ms (TYP.), but can be adjusted to set a longer time using an external resistor and capacitor.

In PWM/PFM switching control mode, provides fast response, low ripple and high efficiency over the full range of loads (from light load to heavy load).

With the UVLO (Under Voltage Lock Out) function, the internal driver transistor is forced OFF when input voltage becomes lower than detect voltage. The series includes current limit, thermal shutdown, and short-circuit protection.

Two types of package SOT-26W and USP-6C are available.

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Oct 11, 2012
Product News
16V Step-down DC/DC Converter with Internal Driver Tr. XC9246 / XC9247 Series

Typical Application Circuit

Features

Input Voltage Range 4.5V~16V
(The VIN range depends on the product)
Output Voltage Range 1.2V~5.6V(VFB=1.0V)
(The VIN range depends on the product)
Output Current 1A(VIN≧6V and VOUT/VIN≦50%)
1A(VIN<6V and VOUT/VIN≦40%)
Efficiency 90%(VIN=12V,VOUT=5V,IOUT=200mA)
Oscillation Frequency 1.2MHz
Maximum Duty Cycle 80%
Soft-Start Internally fixed 1.5ms
Adjustable by RC
Control Methods PWM/PFM automatic switching control
Protection Circuits Current Limit(Integral Latching)
Thermal Shut Down
Short Circuit Protection
UVLO 4.15V,5.65V,7.65V
Capacitor Low ESR Ceramic
Operating Ambient Temperature -40℃~+85℃
Environmentally Friendly EU RoHS compliant, Pb free

Packages

DATA SHEET

Technical Document

Quality Reports

FAQ

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

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?
Answer

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

QuestionWhat does the FB product mean?
Answer

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?
Answer

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.

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