XC9235 Datasheet, PDF (1/28 Pages) Torex Semiconductor – 600mA Driver Tr. Built-In, Synchronous Step-Down DC/DC Converters

XC9235/XC9236/XC9237 Series
ETR0514-007
600mA Driver Tr. Built-In, Synchronous Step-Down DC/DC Converters
˙GENERAL DESCRIPTION
ˑGreenOperation Compatible
The XC9235/XC9236/XC9237 series is a group of synchronous-rectification type DC/DC converters with a built-in 0.42Њ
P-channel driver transistor and 0.52ЊN-channel switching transistor, designed to allow the use of ceramic capacitors. The ICs
enable a high efficiency, stable power supply with an output current of 600mA to be configured using only a coil and two
capacitors connected externally. Operating voltage range is from 2.0V to 6.0V. Output voltage is internally set in a range from
0.8V to 4.0V in increments of 50mV (accuracy: ʶ2.0%). With the built-in oscillator, ether 1.2MHz or 3.0MHz can be selected
for suiting to your particular application. As for operation mode, the XC9235 series is PWM control, the XC9236 series is
automatic PWM/PFM switching control and the XC9237 series can be manually switched between the PWM control mode and
the automatic PWM/PFM switching control mode, allowing fast response, low ripple and high efficiency over the full range of
loads (from light load to heavy load).
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 1.0ЖA or less. With the built-in UVLO (Under Voltage Lock Out) function, the internal
P-channel driver transistor is forced OFF when input voltage becomes 1.4V or lower.
The XC9235B/XC9236B/XC9237B series provide short-time turn-on by the soft start function internally set in 0.25 ms (TYP).
The XC9235B(C)/XC9236B(C)/XC9237B(C) integrate C_L auto discharge function which enables the electric charge at the output
capacitor C_L to be discharged via the internal auto-discharge switch located between the L_X and V_SS pins. When the devices
enter stand-by mode, output voltage quickly returns to the V_SS level as a result of this function.
Two types of package SOT-25 and USP-6C are available.
˙APPLICATIONS
˔Mobile phones
˔Bluetooth equipment
˔PDAs, portable communication modem
˔Portable games
˔Digital cameras, video cameras
˔Cordless phones
˔Notebook computers
˙FEATURES
P-ch Driver Transistor Built-In : ON resistance 0.42Њ
N-ch Driver Transistor Built-In : ON resistance 0.52Њ
Input Voltage
: 2.0V ~ 6.0V
Output Voltage
: 0.8V ~ 4.0V
High Efficiency
: 92% (TYP.)
Output Current
: 600mA
Oscillation Frequency
: 1.2MHz, 3.0MHz (+15%)
Maximum Duty Cycle
: 100%
Control Methods
: PWM (XC9235)
PWM/PFM Auto (XC9236)
PWM/PFM Manual (XC9237)
Soft-Start Circuit Built-In
Current Limiter Circuit Built-In (Constant Current & Latching)
Low ESR Ceramic Capacitor Compatible
Packages
: SOT-25, USP-6C
C_L High Speed Discharge
ʢXC9235B(C)/XC9236B(C)/XC9237B(C) Seriesʣ
High Speed Soft Start
ʢXC9235B/XC9236B/XC9237B Seriesʣ
* Performance depends on external components and wiring on the PCB.
˙TYPICAL APPLICATION CIRCUIT ˙TYPICAL PERFORMANCE
CHARACTERISTICS
˔Efficiency vs. Output CurrentʢFOSC=1.2NHz, VOUT=1.8Vʣ
100 ^{PWM/PFM Automatic Sw itching Control}
90
80
70
VIN= 4.2V
60
3.6V
50 ^2.4V
40
30
PWM Control
VIN= 4.2V
3.6V
2.4V
20
10
0
0.1
1
10
100
1000
Output Current:IOUT(mA)
1/28