XC9235/XC9236/XC9237
Series
600mA Driver Tr. Built-In, Synchronous Step-Down DC/DC Converters
ETR0514-009
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 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 (A/B/C types only) and USP-6C are available.
■GENERAL
DESCRIPTION
☆GreenOperation
Compatible
■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
: 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)
■TYPICAL
APPLICATION CIRCUIT
●XC9235/XC9236/XC9237
A/B/C/E/G types (Output Voltage Fixed)
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
C
L
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（f
OSC
=1.2MHz, V
OUT
=1.8V）
●XC9235/XC9236/XC9237
D/F types (Output Voltage Externally Set)
Efficiency: EFFI (%)
Efficency:EFFI(%)
100
90
80
70
60
50
40
30
20
10
0
PWM/PFM Automatic Sw itching Control
VIN= 4.2V
3.6V
2.4V
PWM Control
VIN= 4.2V
3.6V
2.4V
0.1
1
10
100
1000
Output Current:IOUT(mA)
1/32
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
5
3
1
PIN NAME
V
IN
V
SS
CE / MODE
V
OUT
FB
FUNCTION
Power Input
Ground
High Active Enable / Mode Selection Pin
Fixed Output Voltage Pin (A/B/C/E/G types)
Output Voltage Sense Pin (D/F types)
Switching Output
Lx
2/32
XC9235/XC9236/XC9237
Series
■PRODUCT
CLASSIFICATION
●Ordering
Information
XC9235①②③④⑤⑥-⑦
(
*1
)
XC9236①②③④⑤⑥-⑦
(
*1
)
*1
XC9237①②③④⑤⑥-⑦
( )
DESIGNATOR
DESCRIPTION
Fixed Output voltage
Operating Voltage from 2.0V
①
Fixed Output voltage
Operating Voltage from 1.8V
Adjustable Output voltage
Operating Voltage from 1.8V
Fixed PWM control
PWM / PFM automatic switching control
Fixed PWM control PWM / PFM automatic switching manual selection
SYMBOL
A
B
C
E
G
D
F
DESCRIPTION
No C
L
auto discharge, Low speed soft-start
C
L
auto discharge, High speed soft-start
C
L
auto discharge, Low speed soft-start
C
L
auto discharge, Low speed soft-start
C
L
auto discharge, High speed soft-start
C
L
auto discharge, Low speed soft-start
C
L
auto discharge, High speed soft-start
Fixed output voltage types
e.g. V
OUT
=2.8V→②=2,
③=8
V
OUT
=2.85V→②=2,
③=L
0.05V 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
Adjustable Voltage types (Vref=0.8V) for D/F types
1.2MHz
3.0MHz
SOT-25
(*3)
SOT-25 (Halogen & Antimony free)
(*3)
USP-6C
USP-6C (Halogen & Antimony free)
(*4)
②③
Output Voltage
08 ~ 40
08
④
Oscillation Frequency
C
D
MR
⑤⑥-⑦
Packages
(*2)
Taping Type
MR-G
ER
ER-G
(*1)
(*2)
(*3)
(*4)
The “-G” suffix indicates that the products are Halogen and Antimony free as well as being fully RoHS compliant.
The device orientation is fixed in its embossed tape pocket. For reverse orientation, please contact your local Torex sales office or
representative. (Standard orientation:
⑤R-⑦,
Reverse orientation:
⑤L-⑦)
SOT-25 package is available for the A/B/C series only.
The D/E/F/G series for halogen & antimony free and RoHS compliant is under development.
3/32
XC9235/XC9236/XC9237
Series
■BLOCK
DIAGRAM
●XC9235
/ XC9236 / XC9237
・XC9235/XC9236/XC9237
A
Aシリーズ
Series
Phase
Compensation
●XC9235
/ XC9236
・XC9235/XC9236/XC9237
/ XC9237
B,C,E,Gシリーズ
B/C/E/G Series
Phase
Compensation
VOUT
R2
Current Feedback
Current Limit
CFB
Error Amp.
FB
Logic
VOUT
R2
Synch
Buffer
Drive
Current Feedback
Current Limit
CFB
Error Amp.
FB
Logic
PWM
Comparator
PWM
Comparator
Synch
Buffer
Drive
R1
Lx
VIN
R1
VSHORT
Lx
VIN
Vref with
Soft Start,
CE
VSHORT
PWM/PFM
Selector
Vref with
Soft Start,
CE
PWM/PFM
Selector
CE/
Ramp Wave
Generator
OSC
Ramp Wave
Generator
OSC
UVLO Cmp
UVLO
UVLO Cmp
UVLO
VSS
R3
VSS
CE/MODE
Control
Logic
R3
R4
CE/MODE
R4
CE/MODE
Control
Logic
CE/MODE
・XC9235/XC9236/XC9237
●XC9235
/ XC9236 / XC9237
D,Fシリーズ
D/F Series
Phase
Compensation
FB
Error Amp.
PWM
Comparator
Current Feedback
Current Limit
Logic
Synch
Buffer
Drive
Lx
VIN
Vref with
Soft Start,
CE
VSHORT
PWM/PFM
Selector
CE/
Ramp Wave
Generator
OSC
UVLO Cmp
UVLO
VSS
R3
R4
CE/MODE
Control
Logic
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.
Diodes inside the circuit are ESD protection diodes and parasitic diodes.
■ABSOLUTE
MAXIMUM RATINGS
PARAMETER
V
IN
Pin Voltage
Lx Pin Voltage
V
OUT
Pin Voltage
FB Pin Voltage
CE / MODE Pin Voltage
Lx Pin Current
Power Dissipation
SOT-25
(*Ta=25℃)
USP-6C
Operating Temperature Range
Storage Temperature Range
SYMBOL
V
IN
V
Lx
V
OUT
V
FB
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
- 0.3 ~ 6.5
±1500
250
100
- 40 ~ + 85
- 55 ~ + 125
Ta=25℃
UNIT
V
V
V
V
V
mA
mW
O
O
C
C
4/32
XC9235/XC9236/XC9237
Series
■ELECTRICAL
CHARACTERISTICS
XC9237A18Cxx, V
OUT
=1.8V, f
OSC
=1.2MHz, Ta=25℃
PARAMETER
Output Voltage
Operating Voltage Range
Maximum Output Current
UVLO Voltage
Supply Current
Stand-by Current
Oscillation Frequency
PFM Switching Current
PFM Duty Limit
Maximum Duty Cycle
Minimum Duty Cycle
Efficiency
(*2)
SYMBOL
V
OUT
V
IN
I
OUTMAX
V
UVLO
I
DD
I
STB
f
OSC
I
PFM
DTY
LIMIT_PFM
DTY
MAX
DTY
MIN
EFFI
R
LxH
R
LxH
R
LxL
R
LxL
I
LeakH
I
LeakL
I
LIM
△V
OUT
/
(V
OUT
・△topr)
V
CEH
V
CEL
CONDITIONS
When connected to external components,
V
IN
=V
CE
=5.0V, I
OUT
=30mA
V
IN
=V
OUT(E)
+2.0V, V
CE
=1.0V,
(*9)
When connected to external components
V
CE
=V
IN
, V
OUT
=0V,
(*1, *11)
Voltage which Lx pin holding “L” level
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,
V
IN
=V
OUT(E)
+2.0V, V
CE
=1.0V, I
OUT
=100mA
When connected to external components,
(*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)
MIN.
1.764
2.0
600
1.00
-
-
1020
120
TYP.
1.800
-
-
1.40
15
0
1200
160
200
MAX.
1.836
6.0
-
1.78
33
1.0
1380
200
UNIT
V
V
mA
V
μA
μA
kHz
mA
%
CIRCUIT
①
①
①
②
③
③
①
①
①
②
②
①
④
④
④
-
⑤
⑤
⑥
①
③
③
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×0.9V
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
(*3)
V
IN
=V
CE
=5.0V, V
OUT
=0V, I
Lx
=100mA
V
IN
=V
CE
=3.6V, V
OUT
=0V, I
Lx
=100mA
V
IN
=V
CE
=5.0V
V
IN
=V
CE
=3.6V
(*4)
(*4)
(*3)
100
-
-
-
-
-
-
-
-
(*8)
-
-
92
0.35
0.42
0.45
0.52
0.01
0.01
1050
±100
-
-
-
0
-
0.55
0.67
0.66
0.77
1.0
1.0
1350
-
6.0
0.25
%
%
%
Ω
Ω
Ω
Ω
μA
μA
mA
ppm/℃
V
V
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
Lx SW "L" Leak Current
(*10)
(*5)
(*5)
V
IN
=V
OUT
=5.0V, V
CE
=0V, Lx=0V
V
IN
=V
OUT
=5.0V, V
CE
=0V, Lx=5.0V
V
IN
=V
CE
=5.0V, V
OUT
=V
OUT(E)
×0.9V
I
OUT
=30mA, -40℃≦Topr≦85℃
V
OUT
=0V, Applied voltage to V
CE
,
(*11)
Voltage changes Lx to “H” level
V
OUT
=0V, Applied voltage to V
CE
,
(*11)
Voltage changes Lx to “L” level
When connected to external components,
(*6)
I
OUT
=1mA , Voltage which oscillation frequency
(*13)
becomes 1020 kHz≦f
OSC
≦1380kHz
When connected to external components,
(*6)
I
OUT
=1mA , Voltage which oscillation frequency
(*13)
becomes f
OSC
＜1020kHz
V
IN
=V
CE
=5.0V, V
OUT
=0V
V
IN
=5.0V, V
CE
=0V, V
OUT
=0V
When connected to external components,
V
CE
=0V
→
V
IN
, I
OUT
=1mA
V
IN
=V
CE
=5.0V, V
OUT
=0.8×V
OUT(E)
,
(*7)
Short Lx at 1Ω resistance
Sweeping V
OUT
, V
IN
=V
CE
=5.0V, Short Lx at
1Ω resistance, V
OUT
voltage which Lx becomes
“L” level within 1ms
Current Limit
Output Voltage
Temperature Characteristics
CE "H" Voltage
CE "L" Voltage
900
-
0.65
V
SS
PWM "H" Level Voltage
V
PWMH
-
-
V
IN
- 1.0
V
①
PWM "L" Level Voltage
CE "H" Current
CE "L" Current
Soft Start Time
Latch Time
Short Protection Threshold
Voltage
V
PWML
I
CEH
I
CEL
t
SS
t
LAT
V
SHORT
V
IN
–
0.25
- 0.1
- 0.1
0.5
1.0
0.675
-
-
-
1.0
-
0.900
-
0.1
0.1
2.5
20.0
1.150
V
μA
μA
ms
ms
V
①
⑤
⑤
①
⑦
⑦
Test conditions: Unless otherwise stated, V
IN
=5.0V, V
OUT(E)
=Nominal 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 DTY
LIMIT_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.
5/32
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