XCL205 Series

Inductor Built-in Step-Down “micro DC/DC” Converters

The XCL205 series is a synchronous step-down micro DC/DC converter which integrates an inductor and a control IC in one tiny package (2.5mm×2.0mm, H=1.0mm). A stable power supply with an output current of 600mA is configured using only two capacitors connected externally.

Operating voltage range is from 2.0V to 6.0V (XCL20xG: 1.8~6.0V). Output voltage is internally set in a range from 0.8V to 4.0V in increments of 0.05V.

The device is operated by 3.0MHz, and includes 0.42ΩP-ch driver transistor and 0.52ΩN-ch switching transistor. During stand-by, the device is shutdown to reduce current consumption to as low as 1.0μA or less. With the built-in UVLO (Under Voltage Lock Out) function, the internal driver transistor is forced OFF when input voltage becomes 1.4V or lower.

XCL205B series provide short-time turn-on by the soft start function internally set in 0.25 ms (TYP). XCL205B integrate CL auto discharge function which enables the electric charge stored at the output capacitor CL to be discharged via the internal auto-discharge switch located between the LX and VSS pins. When the devices enter stand-by mode, output voltage quickly returns to the VSS level as a result of this function.

Typical Application Circuit


Input Voltage Range 2.0V~6.0V
Output Voltage Range 0.8V~4.0V(Accuracy ±2.0%)
High Efficiency 90%(VIN=4.2V,VOUT=3.3V)
Output Current 600mA
Oscillation Frequency 3.0MHz(Accuracy ±15%)
Maximum Duty Cycle 100%
Capacitor Low ESR Ceramic
Soft-Start Soft-Start Circuit Built-In
Control Methods PWM
CL High Speed Auto Discharge XCL205B/C
High Speed Soft-Start XCL205B
Other Functions Current Limiter Circuit Built-In,(Constant Current & Latching)



Technical Document

Quality Reports


QuestionTell me about XCL205/XCL206/XCL207 Series.

They are coil-integrated step-down DC/DC converters that achieves both a reduction of the mounting area and good characteristics by means of a simple structure whereby the coil is placed on top of the complete DC/DC converter IC. The only components that are needed to output the output current (maximum of 600 mA) are two capacitors, enabling miniaturization when mounting on the board . The simple structure allows existing mass production pieces to be used without degrading the characteristics of the IC, a major advantage.
To limit the height of the combined coil and DC/DC converter to 1 mm, we developed a new ultra-flat package (USP-6EL) with a height of 0.4 mm for the DC/DC converter.

QuestionWhat is the soft-start function?

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

QuestionHow does the CL discharge function work?

The function rapidly releases the charge remained in the CL capacitor to make the VOUT pin voltage zero. The VOUT pin voltage does not reach zero immediately after being turned off by the CE function due to the charge remained in the connected CL capacitor. While the charge in the CL capacitor is gradually reaching zero, the LSI continues operating and does not work with the CE pin signal, which may cause a malfunction. This is why the discharge is required when turning off the CE pin. A larger capacitance of the capacitor needs longer time to be discharged.

QuestionWhat does CL mean?

Load capacitor. Other companies often refer to it as COUT.

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

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.