☆GO-Compatible
Preliminary
◆Synchronous Step-Down DC/DC Converters
◆High Efficiency
: 92%
◆Low Ripple
: 10mV
◆Output Current
: 600mA
◆Oscillation Frequency
: 600kHz,
1.2MHz, 3.0MHz
◆PWM Fixed Control
: (XC9235 series)
◆PWM/PFM Automatic Switching Control : (XC9236 series)
◆Manual Selection of Switching Control : (XC9237 series)
◆Maximum Duty Ratio
: 100%
◆Ceramic Capacitor Compatible
◆Ultra Small Packages
: SOT-25, USP-6C
■APPLICATIONS
■GENERAL DESCRIPTION
■FEATURES
The
XC9235/9236/9237
series
is
a
group
of
synchronous-rectification type DC/DC converters with a
built-in 0.42 Ω P-channel driver transistor and 0.52 Ω
N-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 1.8V to 6.0V.
Output voltage is internally programmable in a range from
0.8V to 4.0V in increments of 50mV . With the built-in oscillator, oscillation frequency is
selectable from 600kHz, 1.2MHz, and 3.0MHz to make
available the frequency best suited 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 load (from
light load to high output current conditions).
The soft start and current control functions are internally
optimized. During standby, all circuits are shutdown to
reduce current consumption to as low as 1.0μA or less.
With the built-in U.V.L.O. (Under Voltage Lock Out) function,
the internal P-channel driver transistor is forced OFF when
input voltage becomes 1.4V or lower.
Two types of
package, SOT-25 (250mW) and USP-6C (100mW), are
available.
■TYPICAL APPLICATION CIRCUIT
●Mobile phones (PDC, GSM, CDMA, IMT2000 etc.)
●Bluetooth equipment
●PDAs, Portable communication modem
●Portable games
●Cameras, Digital cameras
●Cordless phones
●Notebook computers
P-Ch Driver Tr. Built-In
N-Ch Synchronous Driver
Tr. built-in
Input Voltage Range
Output Voltage Range
High Efficiency
Output Current
Oscillation Frequency
: ON resistance 0.42Ω
: ON resistance 0.52Ω
: 1.8V~6.0V
: 0.8V~4.0V
(50mV increments)
: 92% (TYP.)
: 600mA
: 600kHz, 1.2MHz, 3.0MHz
(Fixed frequency accuracy ±15%)
: SOT-25 (SOT-23-5), USP-6C
Packages
Soft-Start Circuit Built-In
Current Limiter Circuit Built-In (Constant Current & Latching)
Low ESR Ceramic Capacitor Compatible
* Performance depends on external components
and wiring on the PCB.
■TYPICAL PERFORMANCE
CHARACTERISTICS
●Efficiency vs. Output Current
(VIN=4.2V, VOUT=1.8V)
100
PWM/PFM Automatic Switching Control
3.0MHz
80
Efficency:EFFI(%)
90
L: 1.5uH (NR3015)
CL: 10uF (ceramic)
70
CIN: 4.7uF (ceramic)
3.0MHz
60
PWM Control
1.2MHz
50
1.2MHz
3.0MHz
40
1.2MHz
L: 4.7uH (NR3015)
30
3MHz PFM
1.2MHz PFM
20
3MHz PWM
10
CL: 10uF (ceramic)
CIN: 4.7uF (ceramic)
1.2MHz PWM
0
0.1
1
10
100
1000
Output Current:IOUT(mA)
1/7
XC9235_36_37 ETR_0514_001
XC9235/9236/9237
Series
■PACKAGING INFORMATION
●SOT-25 (SOT-23-5)
●USP-6C
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