XC9235/XC9236/XC9237
Series
600mA Driver Tr. Built-In, Synchronous Step-Down DC/DC Converters
ETR0514-005
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. 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:
±2.0%).
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 1.0μA 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 0.2 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.
■GENERAL
DESCRIPTION
☆GreenOperation
Compatible
■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
N-ch Driver Transistor Built-In
Input Voltage
Output Voltage
High Efficiency
Output Current
Oscillation Frequency
Maximum Duty Cycle
Control Methods
: ON resistance 0.42Ω
: ON resistance 0.52Ω
: 2.0V ~ 6.0V
: 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, USP-6C
C
L
High Speed Discharge
（XC9235B(C)/XC9236B(C)/XC9237B(C)
Series）
High Speed Soft Start
（XC9235B/XC9236B/XC9237B
Series）
* Performance depends on external components and wiring on the PCB.
■TYPICAL
APPLICATION CIRCUIT
■TYPICAL
PERFORMANCE
CHARACTERISTICS
●Efficiency
vs. Output Current（FOSC=1.2NHz, V
OUT
=1.8V）
100
90
80
Efficency:EFFI(%)
70
60
50
40
30
20
10
0
0.1
1
10
100
1000
Output Current:IOUT(mA)
2.4V
VIN= 4.2V
3.6V
PWM Control
VIN= 4.2V
3.6V
2.4V
PWM/PFM Automatic Sw itching Control
1/29
XC9235/XC9236/XC9237
Series
■PIN
CONFIGURATION
Lx
V
OUT
5
4
V
IN
V
SS
CE/MODE
6
5
4
1
2
3
Lx
V
SS
V
OUT
* Please short the V
SS
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
(No. 5) pin.
1
V
IN
2
V
SS
3
CE/MODE
SOT-25
(Top View)
USP-6C
(BOTTOM VIEW)
■PIN
ASSIGNMENT
PIN NUMBER
SOT-25
USP-6C
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
A
B
C
0~4
DESCRIPTION
: CE input logic High Active
: CE input logic High Active, high speed soft start, C
L
discharge
(Under Development)
: CE input logic High Active, C
L
discharge
: Integer number of output voltage
e.g. V
OUT
=2.8V→②=2, V
OUT
=3.3V→②=3
: Decimal number of output voltage
50mV increments: 0.05=A, 0.15=B, 0.25=C, 0.35=D, 0.45=E,
0.55=F, 0.65=H, 0.75=K, 0.85=L, 0.95=M
e.g. V
OUT
=2.8V→②=2,
③=8
V
OUT
=2.85V→②=2,
③=L
: 1.2MHz
: 3.0MHz
: SOT-25 (SOT-23-5)
(B and C series are under development)
: USP-6C
: Embossed tape, standard feed
: Embossed tape, reverse feed
DESCRIPTION
Transistor built-in,
Output voltage internally set
(V
OUT
product),
Soft-start internally set
Output Voltage
①.
②
③
Output Voltage
0~9, A~M
④
Oscillation Frequency
C
D
M
E
⑤
Packages
⑥
Device Orientation
R
L
2/29
XC9235/XC9236/XC9237
Series
■BLOCK
DIAGRAM
●XC9235A
/ XC9236A / XC9237A
●XC9235B(C)
/ XC9236B(C) / XC9237B(C)
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.
Diodes inside the circuit are ESD protection diodes and parasitic diodes.
■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
(*Ta=25℃)
SOT-25
USP-6C
Operating Temperature Range
Storage Temperature Range
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
±1500
250
100
- 40 ~ + 85
- 55 ~ + 125
UNIT
V
V
V
V
mA
mW
O
C
O
C
3/29
XC9235/XC9236/XC9237
Series
■ELECTRICAL
CHARACTERISTICS
XC9237A18Cxx, V
OUT
=1.8V, FOSC=1.2MHz, Ta=25℃
PARAMETER
Output Voltage
Operating Voltage Range
Maximum Output Current
U.V.L.O. Voltage
Supply Current
Stand-by Current
Oscillation Frequency
PFM Switching Current
Maximum I
PFM
Limit
Maximum Duty Cycle
Minimum Duty Cycle
Efficiency
(*2)
SYMBOL
V
OUT
V
IN
I
OUTMAX
V
UVLO
I
DD
I
STB
FOSC
I
PFM
MAXI
PFM
MAXDTY
MINDTY
EFFI
CONDITIONS
When connected to external components,
V
IN
=V
CE
=5.0V, I
OUT
=30mA
MIN.
1.764
2.0
TYP.
MAX.
UNIT CIRCUIT
V
V
mA
V
μA
μA
kHz
mA
%
%
%
%
Ω
Ω
Ω
Ω
μA
μA
mA
ppm/℃
V
V
V
①
①
①
②
③
③
①
①
①
②
②
①
④
④
④
-
⑤
⑤
⑥
①
③
③
①
1.800 1.836
-
-
1.40
15
0
1200
160
200
-
-
92
0.35
0.42
0.45
0.52
0.01
0.01
1050
±100
-
-
-
6.0
-
1.78
33
1.0
1380
200
-
0
-
0.55
0.67
0.66
0.77
1.0
1.0
1350
-
V
IN
0.25
V
IN
-
1.0
-
0.1
0.1
2.5
20.0
R
LxH
R
LxH
R
LxL
R
LxL
I
LeakH
I
LeakL
I
LIM
△V
OUT
I =30mA, -40℃≦Topr≦85℃
Temperature Characteristics
V
OUT
・△topr
OUT
V
OUT
=0V, Applied voltage to V
CE
,
CE "H" Voltage
V
CEH
(*11)
Voltage changes Lx to “H” level
V
OUT
=0V, Applied voltage to V
CE
,
CE "L" Voltage
V
CEL
Voltage changes Lx to “L” level
(*11)
When connected to external components,
I
OUT
=1mA
(*6)
, Voltage which oscillation
PWM "H" Level Voltage
V
PWMH
frequency becomes 1020 kHz≦FOSC≦
(*13)
1380kHz
When connected to external components,
PWM "L" Level Voltage
V
PWML
I
OUT
=1mA
(*6)
, Voltage which oscillation
frequency becomes FOSC＜1020kHz
(*13)
CE "H" Current
I
CEH
V
IN
=V
CE
=5.0V, V
OUT
=0V
CE "L" Current
I
CEL
V
IN
=5.0V, V
CE
=0V, V
OUT
=0V
When connected to external components,
Soft Start Time
T
SS
V
CE
=0V
→
V
IN
, I
OUT
=1mA
V
IN
=V
CE
=5.0V, V
OUT
=0.8×V
OUT(E)
,
Latch Time
T
LAT
(*7)
Short Lx at 1Ω resistance
Sweeping V
OUT
, V
IN
=V
CE
=5.0V, Short Lx at
Short Protection
V
SHORT
1Ω resistance, V
OUT
voltage which Lx
Threshold Voltage
becomes “L” level within 1ms
Lx SW "H" ON Resistance 1
Lx SW "H" ON Resistance 2
Lx SW "L" ON Resistance 1
Lx SW "L" ON Resistance 2
Lx SW "H" Leak Current
(*5)
Lx SW "L" Leak Current
(*5)
Current Limit
(*10)
Output Voltage
V
IN
=V
OUT(E)
+2.0V, V
CE
=1.0V,
600
When connected to external components
(*9)
V
CE
=V
IN
, V
OUT
=0V,
1.00
Voltage which Lx pin holding “L” level
(*1, *11)
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×1.1V
-
V
IN
=5.0V, V
CE
=0V, V
OUT
=V
OUT(E)
×1.1V
-
When connected to external components,
1020
V
IN
=V
OUT(E)
+2.0V, V
CE
=1.0V, I
OUT
=100mA
When connected to external components,
120
(*12)
V
IN
=V
OUT(E)
+2.0V, V
CE
=V
IN
, I
OUT
=1mA
V
CE
=V
IN
=(C-1), I
OUT
=1mA
(*12)
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×0.9V
100
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×1.1V
-
When connected to external components,
-
V
CE
=V
IN
=V
OUT(E)
+1.2V, I
OUT
=100mA
V
IN
=V
CE
=5.0V, V
OUT
=0V, I
Lx
=100mA
(*3)
-
(*3)
V
IN
=V
CE
=3.6V, V
OUT
=0V, I
Lx
=100mA
-
(*4)
V
IN
=V
CE
=5.0V
-
(*4)
V
IN
=V
CE
=3.6V
-
V
IN
=V
OUT
=5.0V, V
CE
=0V, Lx=0V
-
V
IN
=V
OUT
=5.0V, V
CE
=0V, Lx=5.0V
-
(*8)
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×0.9V
900
-
0.65
V
SS
-
V
IN
–
0.25
- 0.1
- 0.1
0.5
1.0
-
-
-
1.0
-
V
μA
μA
ms
ms
V
①
⑤
⑤
①
⑦
⑦
0.675 0.900 1.150
Test conditions: Unless otherwise stated, V
IN
=5.0V, V
OUT(E)
=Setting Voltage
NOTE:
*1: Including hysteresis operating voltage range.
*2: EFFI = { ( output voltage×output current )
/
( input voltage×input current) }×100
*3: ON resistance (Ω)= (V
IN
- Lx pin measurement voltage)
/
100mA
*4: R&D value
*5: When temperature is high, a current of approximately 10μA (maximum) may leak.
*6: The CE/MODE pin of the XC9237A series works also as an external switching pin of PWM control and PWM/PFM control. When the IC is in the
operation, control is switched to the automatic PWM/PFM switching mode when the CE/MODE pin voltage is equal to or greater than V
IN
minus
0.3V, and to the PWM mode when the CE/MODE pin voltage is equal to or lower than V
IN
minus 1.0V and equal to or greater than V
CEH
.
*7: Time until it short-circuits V
OUT
with GND via 1Ωof resistor from an operational state and is set to Lx=0V from current limit pulse generating.
*8: When V
IN
is less than 2.4V, limit current may not be reached because voltage falls caused by ON resistance.
*9: When the difference between the input and the output is small, some cycles may be skipped completely before current maximizes.
If current is further pulled from this state, output voltage will decrease because of P-ch driver ON resistance.
*10: Current limit denotes the level of detection at peak of coil current.
*11: “H”=V
IN
~V
IN
-1.2V, “L”=+0.1V~-0.1V
*12: XC9235 series exclude I
PFM
and MAXI
PFM
because those are only for the PFM control’s functions.
*13: XC9235/9236 series exclude V
PWMH
and V
PWML
because those are only for the XC9237 series’ functions.
4/29
XC9235/XC9236/XC9237
Series
■ELECTRICAL
CHARACTERISTICS (Continued)
XC9237A18Dxx, V
OUT
=1.8V, FOSC=3.0MHz, Ta=25℃
PARAMETER
Output Voltage
Operating Voltage Range
Maximum Output Current
U.V.L.O. Voltage
Supply Current
Stand-by Current
Oscillation Frequency
PFM Switching Current
Maximum IPFM Limit
Maximum Duty Cycle
Minimum Duty Cycle
Efficiency
Lx SW "H" ON Resistance 1
Lx SW "H" ON Resistance 2
Lx SW "L" ON Resistance 1
Lx SW "L" ON Resistance 2
Lx SW "H" Leak Current
(*5)
Lx SW "L" Leak Current
(*5)
Current Limit
(*10)
Output Voltage
SYMBOL
V
OUT
V
IN
I
OUTMAX
V
UVLO
I
DD
I
STB
FOSC
I
PFM
MAXI
PFM
MAXDTY
MINDTY
EFFI
CONDITIONS
When connected to external components,
V
IN
=V
CE
=5.0V, I
OUT
=30mA
MIN.
1.764
2.0
V
IN
=V
OUT(E)
+2.0V, V
CE
=1.0V,
600
When connected to external components
(*9)
V
CE
=V
IN
, V
OUT
=0V,
1.00
Voltage which Lx pin holding “L” level
(*1,*11)
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×1.1V
-
V
IN
=5.0V, V
CE
=0V, V
OUT
=V
OUT(E)
×1.1V
-
When connected to external components,
2550
V
IN
=V
OUT(E)
+2.0V, V
CE
=1.0V, I
OUT
=100mA
When connected to external components,
170
V
IN
=V
OUT(E)
+2.0V, V
CE
=V
IN
, I
OUT
=1mA
(*12)
V
CE
=V
IN
=(C-1), I
OUT
=1mA
(*12)
-
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×0.9V
100
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×0.1V
-
When connected to external components,
-
V
CE
=V
IN
＝V
OUT(E)
+1.2V, I
OUT
=100mA
V
IN
=V
CE
=5.0V, V
OUT
=0V, I
Lx
=100mA
(*3)
-
(*3)
V
IN
=V
CE
=3.6V, V
OUT
=0V, I
Lx
=100mA
-
(*4)
V
IN
=V
CE
=5.0V
-
(*4)
V
IN
=V
CE
=3.6V
-
V
IN
=V
OUT
=5.0V, V
CE
=0V, Lx=0V
-
V
IN
=V
OUT
=5.0V, V
CE
=0V, Lx=5.0V
-
(*8)
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×0.9V
900
-
0.65
V
SS
-
V
IN
–
0.25
- 0.1
- 0.1
0.5
1.0
TYP.
MAX. UNIT CIRCUIT
V
V
mA
V
μA
μA
kHz
mA
%
%
%
%
Ω
Ω
Ω
Ω
μA
μA
mA
ppm/℃
V
V
V
①
①
①
③
②
②
①
①
①
③
③
①
④
④
-
-
⑤
⑤
⑥
①
③
③
①
1.800 1.836
-
-
1.40
21
0
3000
220
200
-
-
86
0.35
0.42
0.45
0.52
0.01
0.01
1050
±100
-
-
-
6.0
-
1.78
35
1.0
3450
270
300
-
0
-
0.55
0.67
0.66
0.77
1.0
1.0
1350
-
V
IN
0.25
V
IN
-
1.0
-
0.1
0.1
3.0
20
R
LxH
R
LxH
R
LxL
R
LxL
I
LeakH
I
LeakL
I
LIM
△V
OUT
I =30mA, -40℃≦Topr≦85℃
Temperature Characteristics
V
OUT
・△topr
OUT
V
OUT
=0V, Applied voltage to V
CE
,
CE "H" Voltage
V
CEH
Voltage changes Lx to “H” level
(*11)
V
OUT
=0V, Applied voltage to V
CE
,
CE "L" Voltage
V
CEL
(*11)
Voltage changes Lx to “L” level
When connected to external components,
I
OUT
=1mA
(*6)
, Voltage which oscillation
PWM "H" Level Voltage
V
PWMH
frequency becomes 2550kHz≦FOSC≦
3450kHz
(*13)
When connected to external components,
PWM "L" Level Voltage
V
PWML
I
OUT
=1mA
(*6)
, Voltage which oscillation
frequency becomes FOSC＜2550kHz
(*13)
CE "H" Current
I
CEH
V
IN
=V
CE
=5.0V, V
OUT
=0V
CE "L" Current
I
CEL
V
IN
=5.0V, V
CE
=0V, V
OUT
=0V
When connected to external components,
Soft Start Time
T
SS
V
CE
=0V
→
V
IN
, I
OUT
=1mA
V
IN
=V
CE
=5.0V, V
OUT
=0.8×V
OUT(E)
,
Latch Time
T
LAT
Short Lx at 1Ω resistance
(*7)
Sweeping V
OUT
, V
IN
=V
CE
=5.0V, Short Lx at
Short Protection
1Ω resistance, V
OUT
voltage which Lx
V
SHORT
Threshold Voltage
becomes “L” level within 1ms
(*4)
-
-
-
0.9
-
V
μA
μA
ms
ms
V
①
⑤
⑤
①
⑦
⑦
0.675 0.900 1.150
Test conditions: Unless otherwise stated, V
IN
=5.0V, V
OUT(E)
=Setting Voltage
NOTE:
*1: Including hysteresis operating voltage range.
*2: EFFI = { ( output voltage×output current )
/
( input voltage×input current) }×100
*3: ON resistance (Ω)= (V
IN
- Lx pin measurement voltage)
/
100mA
*4: R&D value
*5: When temperature is high, a current of approximately 10μA (maximum) may leak.
*6: The CE/MODE pin of the XC9237A series works also as an external switching pin of PWM control and PWM/PFM control. When the IC is in the
operation, control is switched to the automatic PWM/PFM switching mode when the CE/MODE pin voltage is equal to or greater than V
IN
minus
0.3V, and to the PWM mode when the CE/MODE pin voltage is equal to or lower than V
IN
minus 1.0V and equal to or greater than V
CEH
.
*7: Time until it short-circuits V
OUT
with GND via 1Ωof resistor from an operational state and is set to Lx=0V from current limit pulse generating.
*8: When V
IN
is less than 2.4V, limit current may not be reached because voltage falls caused by ON resistance.
*9: When the difference between the input and the output is small, some cycles may be skipped completely before current maximizes.
If current is further pulled from this state, output voltage will decrease because of P-ch driver ON resistance.
*10: Current limit denotes the level of detection at peak of coil current.
*11: “H”=V
IN
~V
IN
-1.2V, “L”=+0.1V~-0.1V
*12: XC9235 series exclude I
PFM
and MAXI
PFM
because those are only for the PFM control’s functions.
*13: XC9235/9236 series exclude V
PWMH
and V
PWML
because those are only for the XC9237 series’ functions.
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