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
☆GO-Compatible
■APPLICATIONS
●Mobile
phones (PDC, GSM, CDMA, IMT2000 etc.)
●Bluetooth
equipment
●PDAs,
Portable communication modem
●Portable
games
●Cameras,
Digital cameras
●Cordless
phones
●Notebook
computers
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 <accuracy:
±1.5%(±
2.0%)>. 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.
■GENERAL
DESCRIPTION
■FEATURES
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
APPLICATION CIRCUIT
■TYPICAL
PERFORMANCE
CHARACTERISTICS
●Efficiency
vs. Output Current
(V
IN
=4.2V, V
OUT
=1.8V)
100
PWM/PFM Automatic Switching Control
90
80
Efficency:EFFI(%)
70
60
50
40
30
20
10
0
0.1
1
10
100
3.0MHz
1.2MHz
3MHz PFM
1.2MHz PFM
3MHz PWM
1.2MHz PWM
3.0MHz
L: 1.5uH (NR3015)
CL: 10uF (ceramic)
3.0MHz
1.2MHz
PWM Control
CIN: 4.7uF (ceramic)
1.2MHz
L: 4.7uH (NR3015)
CL: 10uF (ceramic)
CIN: 4.7uF (ceramic)
1000
Output Current:IOUT(mA)
1/7
XC9235_36_37 ETR_0514_001
XC9235/9236/9237
Series
■PIN
CONFIGURATION
Lx
5
VOUT
4
VIN 6
VSS 5
1 Lx
2 VSS
3 VOUT
1
VIN
3
2
VSS
CE/MODE
CE/MODE 4
SOT-25 (TOP VIEW)
USP-6C
(BOTTOM VIEW)
* Please short the V
SS
pin (pin no. 2 and 5).
* The dissipation pad for the USP-6C package should
be solder-plated in recommended mount pattern and
metal masking so as to enhance mounting strength
and heat release. If the pad needs to be connected
to other pins, it should be connected to the V
SS
pin.
(pin no. 5).
■PIN
ASSIGNMENT
PIN NUMBER
SOT-25
USP-6B
1
6
2
2, 5
3
4
4
3
5
1
PIN NAME
V
IN
V
SS
CE / MODE
V
OUT
Lx
FUNCTION
Power Input
Ground
Chip Enable Mode Switch
Output Voltage Sense
Switching Output
■PRODUCT
CLASSIFICATION
●Ordering
Information
XC9235①②③④⑤⑥
XC9236①②③④⑤⑥
XC9237①②③④⑤⑥
DESIGNATOR
PWM fixed control
PWM / PFM automatic switching control
PWM fixed control PWM / PFM automatic switching, manual switching
SYMBOL
DESCRIPTION
①
DESCRIPTION
Transistor built-in,
Output voltage internally
set (V
OUT
product),
Soft-start internally set
Current limit: 900mA
Output Voltage
A
: CE input logic High Active
②
0~4
③
Output Voltage
0~9,
A~M
6
C
D
M
D
R
L
④
⑤
⑥
Oscillation Frequency
Package
Device Orientation
: Integer number of output voltage
e.g. V
OUT
=2.8V→②=2
: Decimal number of output voltage
50mV increments: 05=A, 15=B, 25=C, 35=D, 45=E, 55=F, 65=H, 75=K,
85=L, 95=M
e.g. V
OUT
=2.8V→②=2,
③=8
V
OUT
=2.85V→②=2,
③=L
600kHz
1.2MHz
3.0MHz
SOT-25 (SOT-23-5)
USP-6C
Embossed tape, standard feed
Embossed tape, reverse feed
2/7
XC9235/9236/9237
Series
■BLOCK
DIAGRAM
Phase
Compensation
R2
Error A mp.
Current Feedback
Current Limit
PW M
Comparator
Logic
VOUT
R1
VIN
V ref w ith
Sof t Start,
CE
PW M/PFM
Selector
Synch.
Buf f er
Drive
Lx
U.V .L.O. Cmp
VSS
R3 U.V .L.O.
Ramp Wave
Generator
OSC
CE/ MODE
Control Logic
R4
CE/MODE
NOTE: The signal from CE/MODE Control Logic to PWM/PFM Selector is being fixed to "L" level inside,
and XC9235 series chooses only PWM control.
The signal from CE/MODE Control Logic to PWM/PFM Selector is being fixed to "H" level inside,
and XC9236 series chooses only PWM/PFM automatic switching control.
■ABSOLUTE
MAXIMUM RATINGS
Ta=25℃
PARAMETER
V
IN
Pin Voltage
Lx Pin Voltage
V
OUT
Pin Voltage
CE / MODE Pin Voltage
Lx Pin Current
Power Dissipation
SOT-25
USP-6C
SYMBOL
V
IN
V
Lx
V
OUT
V
CE
I
Lx
Pd
Topr
Tstg
RATINGS
- 0.3 ~ 6.5
- 0.3 ~ V
IN
+ 0.3 or 6.5V
- 0.3 ~ 6.5
- 0.3 ~ 6.5
±1200
600 *
1100 *
- 40 ~ + 85
- 55 ~ +125
UNITS
V
V
V
V
mA
mW
℃
℃
Operating Temperature Range
Storage Temperature Range
* When mounted on the PC board.
4/7
XC9235/9236/9237
Series
■ELECTRICAL
CHARACTERISTICS
XC9237A18Cxx
PARAMETER
SYMBOL
CONDITIONS
MIN.
V
OUT
=1.8V, FOSC=1.2MHz, Ta=25℃
TYP.
MAX.
UNIT
CIRCUIT
Output Voltage
Operating Voltage Range
Maximum Output Current
V
OUT
V
IN
I
OUTMAX
V
UVLO
I
DD
Istb
FOSC
I
PFM
MAXIPFM
When connected to external components,
CE=V
IN
, I
OUT
=30mA
-
V
IN
=V
OUT
+ 1.5V,
When connected to external components
CE=V
IN
, V
OUT
=0V, Voltage which Lx pin
voltage holding "L" level
V
IN
=CE=3.6V, V
OUT
=set voltage×1.1V
V
IN
=3.6V, CE=0V,
V
OUT
=set voltage×1.1V
When connected to external components,
I
OUT
=100mA
When connected to external components,
CE=V
IN
, I
OUT
=1mA
1.764
1.8
600
1.00
-
-
1020
-
-
100
-
-
-
-
-
-
-
-
0.65
V
SS
-
V
IN
- 0.3
- 0.1
- 0.1
1.800
-
-
1.40
15
0
1200
160
200
-
-
92
0.42
0.52
0.01
0.01
900
±100
-
-
-
-
-
-
1.0
-
1.836
6.0
-
1.78
-
1.0
1380
-
-
-
0
-
-
-
1.0
1.0
-
-
V
IN
0.25
V
IN
- 1.0
-
0.1
0.1
-
20.0
V
V
mA
V
μA
μA
kHz
mA
%
%
%
%
Ω
Ω
μA
μA
mA
ppm/
℃
U.V.L.O. Voltage
Supply Current
Stand-by Current
Oscillation Frequency
PFM Switch Current
Maximum I
PFM
Limit
Maximum Duty Ratio
Minimum Duty Ratio
Efficiency
Lx SW “H” ON Resistance
Lx SW “L” ON Resistance
Lx SW “H” Leak Current
Lx SW “L” Leak Current
Current Limit
Output Voltage
MAXDTY CE=V
IN
, V
OUT
=0V
MINDTY
EFFI
R
LxH
R
LxL
I
LeakH
I
LeakL
I
LIM
△V
OUT
CE=V
OUT
=V
IN
When connected to external components,
CE=V
IN
=3.0V, I
OUT
=100mA
CE=0.5V
IN
, V
OUT
=0V, I
Lx
=100mA
CE=0.5V
IN
, I
Lx
=100mA
V
IN
=V
OUT
=5.0V, CE=0V, Lx=0V
V
IN
=V
OUT
=5.0V, CE=0V, Lx=5.0V
V
IN
=CE=5.0V, V
OUT
=setting voltage x 0.9V
I
OUT
=30mA, -40℃≦Topr≦85℃
V
OUT
=0V, When CE voltage is applied Lx
determine "H"
V
OUT
=0V, When CE voltage is applied Lx
determine "L"
Temperature Characteristics V
OUT
・△topr
CE “H” Voltage
CE “L” Voltage
PWM “H” Level Voltage
PWM “L” Level Voltage
CE “H” Current
CE “L” Current
Soft-Start Time
Latch Time
Short Protection
Threshold Voltage
V
CEH
V
CEL
V
PWMH
V
PWML
I
CEH
I
CEL
T
SS
Tlat
V
V
V
V
μA
μA
msec
msec
When connected to external components,
CE=0V
→
V
IN
, I
OUT
=1mA
V
IN
=CE=5.0V, VOUT=Setting Voltage x
0.9V, Short Lx by 1Ω resistance
The ratio to the output voltage becomes a
threshold voltage
ex.) When V
OUT
=1.8V, V
SHORT
=0.9V (TYP.)
-
1.0
V
SHORT
-
50
-
%
5/7
PCB Design
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