XCM524 Series

600mA Synchronous Step-Down DC/DC Converter + 500mA LDO,with Delay Function Voltage Detector

The XCM524 series is a multi combination module IC which comprises of a 600mA driver transistor built-in synchronous step down DC/DC converter and a high speed, high current LDO regulator with voltage detector function. The device is housed in small USP-12B01 package which is ideally suited for space conscious applications. The DC/DC converter and the LDO blocks are isolated in the package so that noise interference from the DC/DC to the LDO regulator is minimal.

The DC/DC converter block with a built-in 0.42ΩP-channel MOS driver transistor and 0.52ΩN-channel MOS switching transistor, designed to allow the use of ceramic capacitors. The DC/DC enables a high efficiency, stable power supply with an output current of 600mA to be configured using only a coil and two capacitors connected externally.

The LDO regulator block is precise, low noise, high ripple rejection, low dropout positive voltage regulators with built-in voltage detector. The LDO is also compatible with low ESR ceramic output capacitors. Good output stability is maintained during load fluctuations due to its excellent transient response. The current limiter's fold back circuit also operates as a short circuit protection for the output current.

The voltage detector block of the contains delay circuit. The delay time can be controlled by an external capacitor.

The detector monitors the input voltage of the voltage regulator.

Typical Application Circuit


Input Voltage Range 2.7V~6.0V
Output Voltage Range 0.8V~4.0V(Accuracy ±2%)
High Efficiency 92%(TYP.)
Output Current 600mA(MAX)
Oscillation Frequency 1.2MHz,3.0MHz(±15%)
Protection Circuits Current Limiter Circuit Built-In,(Constant Current & Latching),Soft-Start
Control Fixed PWM, Auto PWM/PFM
MaximumOutput Current 500mA(600mA limit)(2.5V≦VROUT≦4.9V)
Dropout Voltage 200mV@IROUT=100mA
Operating Voltage Range 2.0V~6.0V
Operating Voltage Range 0.9V~5.1V(0.1V increments)(Accuracy ±2%)
VD Detect Voltage Range 2.0V~5.5V(0.1V increments)(Accuracy ±2%)
VR.VD Temperature Stability ±100ppm/℃(TYP.)
High Ripple Rejection 65dB(10kHz)
Low ESR Capacitor Low ESR Ceramic
Operating Ambient Temperature -40℃~85℃
Environmentally Friendly EU RoHS compliant, Pb free



Quality Reports


QuestionWhat does the standby mode mean in the case of the multi channel IC?

It means the state where the entire IC has been turned off. For Torex products, it means that the pin voltages of EN1 and EN2 are both 0V.

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.

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.