XC9135 Series

1A Driver Transistor Built-in, Step-Up DC/DC Converters with Load Disconnection Function

XC9135 series are synchronous step-up DC/DC converters with a 0.2Ω(TYP.) N-ch driver transistor and a 0.2Ω(TYP.) synchronous P-ch switching transistor built-in. A highly efficient and stable current can be supplied up to 1.0A by reducing ON resistance of the built-in transistors.

The series are able to start operation under the condition which has 0.9V input voltage to generate 3.3V output voltage with a 33Ω load resistor, suitable for mobile equipment using only one Alkaline battery or one Nickel metal hydride battery. During the operation of a shutdown, the load disconnection function enables to cut the current conduction path from the input to the output.

The fixed output voltage has 1.8~5.0V (±2.0% accuracy) output voltage range with 0.1V increments. The UVLO function of the XC9135 series is capable to reduce leaking potassium hydroxide by stopping IC operation while battery voltage is declining. The release voltages of UVLO are 0.85V (±6.0% accuracy) and 1.6V (±3.0% accuracy), and selectable voltages range of 0.9V~3.0V.

Typical Application Circuit


Input Voltage Range 0.65V~5.5V
Output Voltage Range 1.8V~5.0V(0.1V increments)
Oscillation Frequency 1.2MHz(Accuracy ±15%)
Input Voltage 1.0A
Output Current 500mA@VOUT=3.3V, VIN=1.8V(TYP.)
Control Methods PWMControl、PWM/PFM auto
Load Transient Response 100mV VOUT=3.3V, VIN=1.8V, IOUT=1mA→200mA
Protection Circuits Over-current limit
Integral latch method
Functions Soft-Start,Load Disconnection Function,CL Auto Discharge Function,Flag-out Function,UVLO
Capacitor Low ESR Ceramic
Operating Ambient Temperature -40℃~+85℃



Technical Document

Quality Reports


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 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.