XCL224 Series

0.7A Inductor Built-in Step-Down “micro DC/DC” Converters

The XCL224 series is a synchronous step-down micro DC/DC converter which integrates an inductor and a control IC in one tiny package (2.25mm×1.5mm, h=0.75mmMAX). 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 XCL224 series uses synchronous rectification at an operating frequency of 3.0MHz. The XCL224 series uses HiSAT-COT+automatic PWM/PFM switching control. The maximum load current can be selected either 700mA.

The series have a high speed soft-start as fast as 0.3ms 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 PGND pins. The power consumption will be less than 1.0μA.

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

Typical Application Circuit


Input Voltage 2.5V~5.5V
Output Voltage 0.8V~3.6V (±2.0%)
Oscillation Frequency 3.0MHz
Output Current 700mA
Efficiency 88% (VIN=5.0V,VOUT=3.3V/300mA)
Control Methods HiSAT-COT
100% Duty Cycle
Automatic PWM/PFM switching control (XCL224)
Circuit Protection Thermal Shut Down
Current Limit Circuit (Drop)
Short Circuit Protection
Functions Soft-Start Circuit Built-In
Output Capacitor Low ESR Ceramic Capacitor
Operating Ambient Temperature -40℃~+105℃
Environmental Friendly EU RoHS Compliant, Pb Free



Technical Document


QuestionHow 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.

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.