XCL301 Series

Inductor Built-in Inverting “micro DC/DC” Converters

The XCL301 series is a inverting micro DC/DC converter which integrates a P-channel FET, an inductor and a control IC in one tiny package (2.5mm×2.0mm, H=1.00mmMAX). A wide operating voltage range of 2.7V to 5.5V enables support for applications that require an internally fixed output voltage (-3.3V).

The XCL301 series uses automatic PFM/fixed off time PWM. In automatic PFM/fixed off time PWM 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 device provides a stable inverting power supply to be configured using only a SBD and two capacitors connected externally.

During stand-by, all circuits are shutdown to reduce current consumption to as low as 0.1μA(TYP) or less. With the built-in UVLO (Under Voltage Lock Out) function, the internal P-channel MOS driver transistor is forced OFF when input voltage becomes 2.2V or lower. The XCL301 integrate CL High Speed discharge function which enables the electric charge at the output capacitor CL to be discharged via the internal discharge.

Typical Application Circuit


Input Voltage Range 2.7V~5.5V
Output Voltage -3.3V
Output Voltage accuracy ±2.0%
Max. Output Current -50mA@VOUT=-3.3V, VIN=3.3V (TYP)
Internal Driver 1.3Ω (Pch Driver Tr.)
Quiescent Current 40μA (TYP.)
Control Methods PFM / Fixed off time PWM Auto
Transient Response -50mV(VIN=3.3V,VOUT=-3.3V,IOUT=1mA→50mA)
Transient Response 550mA
Function Current Limit
CL High Speed Discharge
Ceramic capacitor
Operating Ambient Temperature -40℃~+85℃
Environmentally 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.