XCL221 Series

0.5A Inductor Built-in Step-Down “micro DC/DC” Converters

The XCL221 series is a synchronous step-down micro DC/DC converter which integrates an inductor and a control IC in one tiny package (2.0mm×2.5mm, h=1.0mm). An internal coil simplifies the circuit and enables minimization of noise and other operational trouble due to the circuit wiring. A wide operating voltage range of 2.5V to 5.5V enables support for applications that require an internally fixed output voltage (0.8V to 3.6V). The XCL221 series uses synchronous rectification at an operating frequency of 1.2MHz. The XCL221 series uses HiSAT-COT(*) synchronous rectification.

The series have a high speed soft-start as fast as 0.25ms (TYP.) in typical for quick turn-on. With the built-in UVLO (Under Voltage Lock Out) function, the internal P-channel driver transistor is forced OFF when input voltage becomes 2.0V or lower. When CE=Low, the integrated CL discharge function which enables the electric charge at the output capacitor CL to be discharged via the internal discharge switch located between the LX and GND pins. The power consumption will be less than 1.0μA.

(*) HiSAT-COT is an original Torex term for High Speed Transient Response.

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Jul 1, 2015
Product News
Low noise, higher efficiency with our unique fast transient response control!Step-down "micro DC/DC" converter with integrated 500mA output current coil

Typical Application Circuit


Input Voltage Range 2.5V~5.5V
Output Voltage 0.8V~3.6V(±2.0%)
Oscillation Frequency 1.2MHz
Output Current 0.5A
Efficiency 93%(VIN=5.0V,VOUT=3.3V/200mA)
Control Methods HiSAT-COT Control
100% Duty cycle
Protection Circuits Thermal Shut Down
Current Limit Circuit (Drop)
Short Circuit Protection
Functions Soft-Start
CL Discharge
Capacitor Low ESR Ceramic
Operating Ambient Temperature -40℃~+105℃
Environmentally Friendly EU RoHS compliant, Pb free



Technical Document

Quality Reports


QuestionWhat is the soft-start function?

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