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XC9235 Series

600mA Synchronous Step-Down DC/DC Converters

The XC9235 series is a group of synchronous-rectification type DC/DC converters with a built-in 0.42ΩP-ch MOS driver transistor and 0.52ΩN-ch MOS switching transistor, designed to allow the use of ceramic capacitors. Operating voltage range is from 2.0V to 6.0V (types A～C), 1.8V to 6.0V (types D～G). For the D/F types which have a reference voltage of 0.8V (±2.0%), the output voltage can be set from 0.9V by using two external resistors. The types A/B/C/E/G have a fixed output voltage from 0.8V to 4.0V in increments of 0.05V (±2.0%). The device provides a high efficiency, stable power supply with an output current of 600mA to be configured using only a coil and two capacitors connected externally. With the built-in oscillator, either 1.2MHz or 3MHz can be selected for suiting to your particular application.

The soft start and current control functions are internally optimized. During stand-by, all circuits are shutdown to reduce current consumption to as low as 1.0μA or less. The types B/F/G have a high speed soft-start as fast as 0.25ms in typical for quick turn-on. With the built-in UVLO (Under Voltage Lock Out) function, the internal P-channel MOS driver transistor is forced OFF when input voltage becomes 1.4V or lower.

The types B to G integrate 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 VSS pins. When the devices enter stand-by mode, output voltage quickly returns to the VSS level as a result of this function.

Three types of package SOT-25, USP-6C, and USP-6EL and WLP-5-03 are available.

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Feb 13, 2013
Product News
 【New Product Leaflet】WLP XC6602,XC9235 Series

Typical Application Circuit

Features

P-ch Driver Transistor 0.42Ω
N-ch Switch Transistor 0.52Ω
Input Voltage Range 2.0～6.0V(Types A/B/C),1.8V～6.0V(Types D/E/F/G)
Output Voltage Range 0.8～4.0V
High Efficiency 92%(TYP.)
Output Current 600mA
Oscillation Frequency 1.2MHz、3.0MHz
Soft-Start Circuit Built-In
Capacitor Low ESR Ceramic
Control Methods PWM
Functions CL High Speed Auto Discharge(B/C/D/E/F/G),High Speed Soft Start(B/F/G)

Packages

DATA SHEET

Technical Document

Quality Reports

FAQ

QuestionWhat is the soft-start function?
Answer

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

QuestionHow does the CL discharge function work?
Answer

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?
Answer

Load capacitor. Other companies often refer to it as COUT.

QuestionWhat is the standby current?
Answer

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?
Answer

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?
Answer

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.

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