XC9235/XC9236/XC9237 Series
ETR0514-009
600mA Driver Tr. Built-In, Synchronous Step-Down DC/DC Converters
■GENERAL DESCRIPTION
☆GreenOperation Compatible
The XC9235/XC9236/XC9237 series is a group of synchronous-rectification type DC/DC converters with a built-in 0.42Ω
P-channel driver transistor and 0.52ΩN-channel switching transistor, designed to allow the use of ceramic capacitors. Operating
voltage range is from 2.0V to 6.0V (A∼C types), 1.8V to 6.0V (D∼G types). For the D/F types which have a reference voltage
of 0.8V (accuracy: ±2.0%), the output voltage can be set from 0.9V by using two external resistors. The A/B/C/E/G types have
a fixed output voltage from 0.8V to 4.0V in increments of 0.05V (accuracy: ±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, 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 1.0μA or less. The B/F/G types 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 driver transistor is forced OFF when
input voltage becomes 1.4V or lower.
The B to G types integrate CL auto discharge function which enables the electric charge at the output capacitor CL to be
discharged via the internal auto-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.
Two types of package SOT-25 (A/B/C types only) and USP-6C are available.
■APPLICATIONS
●Mobile phones, Smart phones
●Bluetooth headsets
●Mobile WiMAX PDAs, MIDs, UMPCs
●Portable game consoles
●Digital cameras, Camcorders
●MP3 Players, Portable Media Players
●Notebook computers
■FEATURES
P-ch Driver Transistor Built-In
N-ch Driver Transistor Built-In
Input Voltage
Output Voltage
High Efficiency
Output Current
Oscillation Frequency
Maximum Duty Cycle
Control Methods
■TYPICAL APPLICATION CIRCUIT
●XC9235/XC9236/XC9237
A/B/C/E/G types (Output Voltage Fixed)
: ON resistance 0.42Ω
: ON resistance 0.52Ω
: 2.0V ~ 6.0V (A/B/C types)
: 1.8V ~ 6.0V (D/E/F/G types)
: 0.8V ~ 4.0V
: 92% (TYP.)
: 600mA
: 1.2MHz, 3.0MHz (+15%)
: 100%
: 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 (A/B/C types only), USP-6C
CL High Speed Discharge
: B/C/D/E/F/G types
High Speed Soft Start
: B/F/G types
* Performance depends on external components and wiring on the PCB.
■TYPICAL PERFORMANCE
CHARACTERISTICS
●Efficiency vs. Output Current（fOSC=1.2MHz, VOUT=1.8V）
●XC9235/XC9236/XC9237
100
D/F types (Output Voltage Externally Set)
PWM/PFM Automatic Sw itching Control
90
Efficiency: EFFI (%)
Efficency:EFFI(%)
80
VIN= 4.2V
70
60
50
PWM Control
VIN= 4.2V
3.6V
2.4V
3.6V
2.4V
40
30
20
10
0
0.1
1
10
100
1000
Output Current:IOUT(mA)
1/32
