XCL201/XCL202 Series
ETR28002-009
Inductor Built-in Step-Down “micro DC/DC” Converters
☆Green Operation Compatible
■GENERAL DESCRIPTION
The XCL201/XCL201 series is a synchronous step-down micro DC/DC converter which integrates an inductor and a control
IC in one tiny package (2.5mm×2.0mm, h=1.0mm). A stable power supply with an output current of 400mA is configured using
only 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
0.05V. The device is operated by 1.2MHz, and includes 0.42Ω P-channel driver transistor and 0.52Ω N-channel switching
transistor. As for operation mode, the XCL201 series is PWM control, the XCL202 series is automatic PWM/PFM switching
control, allowing fast response, low ripple and high efficiency over the full range of loads (from light load to heavy load).
During stand-by, the device is 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 driver transistor is forced OFF when input voltage becomes 1.4V or lower.
The series provide short-time turn-on by the soft start function internally set in 0.25ms. The series integrate CL auto
discharge function which enables the electric charge stored at the output capacitor CL to be discharged via the internal autodischarge 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.
■FEATURES
■APPLICATIONS
Ultra Small
Input Voltage
Output Voltage
High Efficiency
Output Current
Oscillation Frequency
Maximum Duty Cycle
Output Capacitor
Function
: 2.5mm×2.0mm, h=1.0mm
: 2.0V ~ 6.0V
: 0.8V ~ 4.0V (±2.0%)
: 92% (VIN=4.2V,VOUT=3.3V)
: 400mA
: 1.2MHz (±15%)
: 100%
: Low ESR Ceramic
: Current Limiter Circuit
(Constant Current & Latching)
Soft-Start Circuit Built-In
CL Discharge
Control Methods
: PWM (XCL201)
PWM/PFM Auto (XCL202)
Operating Ambient Temperature : -40℃ ~ 85℃
Environmentally Friendly
: EU RoHS Compliant, Pb Free
●Mobile phones, Smart phones
●Bluetooth Headsets
●WiMAX PDAs, MIDs, UMPCs
●Portable game consoles
●Digital cameras, Camcorders
●SSD(Solid State Drive)
●PND(Portable Navigation Device)
■TYPICAL APPLICATION CIRCUIT
■ TYPICAL PERFORMANCE
CHARACTERISTICS
XCL201B331BR/XCL202B331BR
100
L1
VIN
400mA
Vss
Vss
VOUT
CE
CIN
4.7μF
Efficency:EFFI(%)
80
LX
CL
10μF
XCL202(PWM/PFM)
60
40
20
* “L1 and LX”, and “L2 and VOUT” is connected by wiring.
XCL201(PWM)
5.0V
L2
(TOP VIEW)
VIN= 5.5V
4.2V
VOUT=3.3V
0
0.01
0.1
1
10
100
1000
Output Current:IOUT (mA)
1/22
XCL201/XCL202 Series
■BLOCK DIAGRAM
L2
L1
Inductor
Phase
Compensation
VOUT
CFB
R1
Current Feedback
Current Limit
PWM
Comparator
Error
Amp.
FB
Logic
R2
Synch
Buffer
Drive
Lx
VSHORT
Vref with
Soft Start,
CE
VIN
PWM/PFM
Selector
VSS
Ramp Wave
Generator
OSC
UVLO Cmp
R3
VSS
UVLO
CE/
CE
Control
Logic
R4
CE
NOTE: The XCL201 offers a fixed PWM control, a signal from CE Control Logic to PWM/PFM Selector is fixed to "L" level inside.
The XCL202 control scheme is PWM/PFM automatic switching, a signal from CE Control Logic to PWM/PFM Selector is fixed
to "H" level inside. The diodes placed inside are ESD protection diodes and parasitic diodes.
■PRODUCT CLASSIFICATION
●Ordering
Information
XCL201①②③④⑤⑥-⑦(*1) Fixed PWM control
XCL202①②③④⑤⑥-⑦(*1) PWM / PFM automatic switching control
DESIGNATOR
ITEM
SYMBOL
①
Functions selection
B
(*1)
(*2)
(*3)
Output voltage options
e.g. 1.2V → ②=1, ③=2
1.25V → ②=1, ③=C
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
②③
Output Voltage
④
Oscillation Frequency
1
Package
(Order Unit)
BR-G(*2)
CL-2025 (3,000pcs/Reel)
ER-G(*3)
CL-2025-02 (3,000pcs/Reel)
⑤⑥-⑦
08 ~ 40
DESCRIPTION
CL auto discharge, High speed soft-start
1.2MHz
The “-G” suffix denotes Halogen and Antimony free as well as being fully EU RoHS compliant.
BR-G is storage temperature range "-40℃ ~ 105℃”.
ER-G is storage temperature range "-40℃ ~ 125℃".
2/22
XCL201/XCL202
Series
■PIN CONFIGURATION
L1
7
VIN 6
1 Lx
* It should be connected the VSS pin (No. 2 and 5) to the GND pin.
Vss 5
2 Vss
* If the dissipation pad needs to be connected to other pins, it should be connected to the GND pin.
CE 4
3 VOUT
* Please refer to pattern layout page for the connecting to PCB.
8
L2
(BOTTOM VIEW)
■PIN ASSIGNMENT
PIN NUMBER
PIN NAME
FUNCTIONS
1
2,5
3
4
6
7
8
Lx
VSS
VOUT
CE
VIN
L1
L2
Switching Output
Ground
Output Voltage
Chip Enable
Power Input
Inductor Electrodes
■ABSOLUTE MAXIMUM RATINGS
(*1)
PARAMETER
SYMBOL
RATINGS
UNITS
VIN Pin Voltage
LX Pin Voltage
VIN
VLX
-0.3 ~ 6.5
-0.3 ~ VIN + 0.3 ≦ 6.5
V
V
VOUT Pin Voltage
CE Pin Voltage
VOUT
VCE
-0.3 ~ 6.5
-0.3 ~ 6.5
V
V
LX Pin Current
Power Dissipation (Ta = 25℃)
ILX
Pd
1500
1000 (40mm x 40mm Standard board) (*1)
mA
mW
Operating Ambient Temperature
CL-2025
Storage
(*2)
Temperature
CL-2025-02
Topr
-40 ~ 85
-40 ~ 105
℃
Tstg
-40 ~ 125
℃
he power dissipation figure shown is PCB mounted and is for reference only.
Please refer to PACKAGING INFORMATION for the mounting condition.
(*2)
Storage temperature, are divided by the product specification of the package.
3/22
XCL201/XCL202 Series
■ELECTRICAL CHARACTERISTICS
XCL201B121BR/XCL202B121BR/XCL201B121ER/XCL202B121ER, VOUT=1.2V, fOSC=1.2MHz, Ta=25℃
PARAMETER
SYMBOL
Output Voltage
VOUT
Operating Voltage Range
VIN
Maximum Output Current
IOUTMAX
UVLO Voltage
VUVLO
Supply Current (XCL201)
CONDITIONS
When connected to external components,
VIN=VCE=5.0V, IOUT=30mA
VIN=VOUT(T)+2.0V, VCE=1.0V
When connected to external components (*8)
VCE=VIN,VOUT=0V
Voltage which Lx pin holding “L” level (*1, *10)
IDD
VIN=VCE=5.0V, VOUT=VOUT(T)×1.1
Stand-by Current
ISTB
Oscillation Frequency
fOSC
PFM Switching Current (*11)
IPFM
VIN=5.0V, VCE=0V, VOUT= VOUT(T)×1.1
When connected to external components,
VIN=VOUT(T)+2.0V, VCE=1.0V , IOUT=100mA
When connected to external components,
VIN=VOUT(T)+2.0V, VCE=VIN , IOUT=1mA
Supply Current (XCL202)
PFM Duty Limit (*11)
DTYLIMIT_PFM
Maximum Duty Cycle
MAXDTY
VIN=VCE=5.0V, VOUT=VOUT (T)×0.9
Minimum Duty Cycle
MINDTY
Efficiency (*2)
EFFI
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" Leakage Current (*5)
Current Limit (*9)
Output Voltage
Temperature Characteristics
RLｘH1
RLｘH2
RLｘL1
RLｘL2
ILeakH
ILIM
△VOUT/
(VOUT・△Topr)
CE "H" Voltage
VCEH
CE "L" Voltage
VCEL
CE "H" Current
CE "L" Current
ICEH
ICEL
Soft Start Time
tSS
Latch Time
tLAT
Short Protection
Threshold Voltage
VSHORT
VIN=VCE=5.0V, VOUT=VOUT (T)×1.1
When connected to external components,
VCE=VIN=VOUT (T)+1.2V, IOUT=100mA
VIN=VCE=5.0V, VOUT=0V,ILX=100mA (*3)
VIN=VCE=3.6V, VOUT=0V,ILX=100mA (*3)
VIN=VCE=5.0V (*4)
VIN=VCE=3.6V (*4)
VIN=VOUT=5.0V, VCE=0V, LX=0V
VIN=VCE=5.0V, VOUT=VOUT (T)×0.9 (*7)
IOUT=30mA
-40℃≦Topr≦85℃
VOUT=0V, Applied voltage to VCE,
Voltage changes Lx to “H” level (*10)
VOUT=0V, Applied voltage to VCE,
Voltage changes Lx to “L” level (*10)
VIN=VCE=5.0V, VOUT=0V
VIN=5.0V, VCE=0V, VOUT=0V
When connected to external components,
VCE=0V→VIN , IOUT=1mA
VIN=VCE=5.0V, VOUT=0.8×VOUT(T)
Short Lx at 1Ω resistance (*6)
Sweeping VOUT, VIN=VCE=5.0V, Short Lx at
1Ω resistance, VOUT voltage which Lx becomes “L”
level within 1ms
VIN=5.0V, LX=5.0V, VCE=0V, VOUT=open
Test frequency=1MHz
ΔT=40℃
CL Discharge
Inductance Value
Allowed Inductor Current
RDCHG
L
IDC
VCE=VIN = 2.0V, IOUT=1mA
UNITS CIRCUIT
MIN.
TYP.
MAX.
1.176
1.200
1.224
V
①
2.0
-
6.0
V
①
400
-
-
mA
①
1.00
1.40
1.78
V
②
-
22
50
-
15
33
μA
②
-
0
1.0
μA
③
1020
1200
1380
kHz
①
140
180
240
mA
⑩
-
200
300
%
①
100
-
-
%
③
-
-
0
%
③
-
86
-
%
①
600
0.35
0.42
0.45
0.52
0.01
800
0.55
0.67
0.65
0.77
1.0
1000
Ω
Ω
Ω
Ω
μA
mA
④
④
⑨
⑥
-
±100
-
ppm/ ℃
①
0.65
-
6.0
V
③
VSS
-
0.25
V
③
-0.1
-0.1
-
0.1
0.1
μA
μA
⑤
⑤
-
0.25
0.40
ms
①
1.0
-
20
ms
⑦
0.450
0.600
0.750
V
⑦
200
-
300
4.7
600
450
-
Ω
μH
mA
⑧
-
Test conditions: Unless otherwise stated, VIN=5.0V, VOUT(T)=Nominal Voltage
NOTE:
(*1)
Including hysteresis operating voltage range.
(*2)
EFFI= { ( output voltage×output current ) / ( input voltage×input current) }×100
(*3)
ON resistance (Ω)=(VIN - Lx pin measurement voltage) / 100mA
(*4)
Design value
(*5)
When temperature is high, a current of approximately 10μA (maximum) may leak.
(*6)
Time until it short-circuits VOUT with GND via 1Ω of resistor from an operational state and is set to Lx=0V from current limit pulse generating.
(*7)
When VIN is less than 2.4V, limit current may not be reached because voltage falls caused by ON resistance.
(*8)
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.
(*9)
Current limit denotes the level of detection at peak of coil current.
(*10)
“H”=VIN ~ VIN-1.2V, “L”=0.1V ~ -0.1V
(*11)
IPFM and DTYLIMIT_PFM are defined only for the XCL202 series which have PFM control function. (Not for the XCL201 series)
4/22
XCL201/XCL202
Series
■ELECTRICAL CHARACTERISTICS (Continued)
XCL201B181BR/XCL202B181BR/XCL201B181ER/XCL202B181ER ,VOUT=1.8V, fOSC=1.2MHz, Ta=25℃
PARAMETER
SYMBOL
Output Voltage
VOUT
Operating Voltage Range
VIN
Maximum Output Current
IOUTMAX
UVLO Voltage
VUVLO
Supply Current (XCL201)
CONDITIONS
When connected to external components,
VIN=VCE=5.0V, IOUT=30mA
VIN=VOUT(E)+2.0V, VCE=1.0V
When connected to external components (*8)
VCE=VIN,VOUT=0V
Voltage which Lx pin holding “L” level (*1, *10)
IDD
VIN=VCE=5.0V, VOUT=VOUT(T)×1.1
Stand-by Current
ISTB
Oscillation Frequency
fOSC
PFM Switching Current (*11)
IPFM
VIN=5.0V, VCE=0V, VOUT=VOUT(T)×1.1
When connected to external components,
VIN=VOUT(T)+2.0V, VCE=1.0V , IOUT=100mA
When connected to external components,
VIN=VOUT(T)+2.0V, VCE=VIN , IOUT=1mA
Supply Current (XCL202)
UNITS CIRCUIT
MIN.
TYP.
MAX.
1.764
1.800
1.836
V
①
2.0
-
6.0
V
①
400
-
-
mA
①
1.00
1.40
1.78
V
②
-
22
50
-
15
33
μA
②
-
0
1.0
μA
③
1020
1200
1380
kHz
①
120
160
200
mA
⑩
PFM Duty Limit (*11)
DTYLIMIT_PFM
VCE=VIN=VOUT(T) +0.5V, IOUT=1mA
-
200
300
%
①
Maximum Duty Cycle
MAXDTY
VIN=VCE=5.0V, VOUT=VOUT (T)×0.9
100
-
-
%
③
Minimum Duty Cycle
MINDTY
-
-
0
%
③
Efficiency (*2)
EFFI
VIN=VCE=5.0V, VOUT=VOUT (T)×1.1
When connected to external components,
VCE=VIN=VOUT (T)+1.2V, IOUT=100mA
VIN=VCE=5.0V, VOUT=0V, ILX=100mA (*3)
VIN=VCE=3.6V, VOUT=0V, ILX=100mA (*3)
VIN=VCE=5.0V (*4)
VIN=VCE=3.6V (*4)
VIN=VOUT=5.0V, VCE=0V, LX=0V
VIN=VCE= 5.0V, VOUT=VOUT (T)×0.9 (*7)
IOUT=30mA
-40℃≦Topr≦85℃
VOUT=0V, Applied voltage to VCE,
Voltage changes Lx to “H” level (*10)
VOUT=0V, Applied voltage to VCE,
Voltage changes Lx to “L” level (*10)
VIN=VCE=5.0V, VOUT=0V
VIN=5.0V, VCE=0V, VOUT=0V
When connected to external components,
VCE=0V→VIN , IOUT=1mA
VIN=VCE=5.0V, VOUT=0.8×VOUT(T)
Short Lx at 1Ω resistance (*6)
Sweeping VOUT, VIN=VCE=5.0V, Short Lx at
1Ω resistance, VOUT voltage which Lx becomes
“L” level within 1ms
VIN=5.0V LX=5.0V VCE=0V VOUT=open
Test frequency=1MHz
ΔT=40℃
-
89
-
%
①
600
0.35
0.42
0.45
0.52
0.01
800
0.55
0.67
0.65
0.77
1.0
1000
Ω
Ω
Ω
Ω
μA
mA
④
④
⑨
⑥
-
±100
-
ppm/ ℃
①
0.65
-
6.0
V
③
VSS
-
0.25
V
③
-0.1
-0.1
-
0.1
0.1
μA
μA
⑤
⑤
-
0.32
0.50
ms
①
1.0
-
20
ms
⑦
0.675
0.900
1.125
V
⑦
200
-
300
4.7
600
450
-
Ω
μH
mA
⑧
-
Lx SW "H" ON Resistance 1
RLｘH1
Lx SW "H" ON Resistance 2
RLｘH2
Lx SW "L" ON Resistance 1
RLｘL1
Lx SW "L" ON Resistance 2
RLｘL2
Lx SW "H" Leakage Current (*5)
ILeakH
Current Limit (*9)
ILIM
Output Voltage
△VOUT/
(VOUT・△Topr)
Temperature Characteristics
CE "H" Voltage
VCEH
CE "L" Voltage
VCEL
CE "H" Current
CE "L" Current
ICEH
ICEL
Soft Start Time
tSS
Latch Time
tLAT
Short Protection
Threshold Voltage
VSHORT
CL Discharge
Inductance Value
Allowed Inductor Current
RDCHG
L
IDC
Test conditions: Unless otherwise stated, VIN=5.0V, VOUT (T)=Nominal Voltage
NOTE:
(*1)
Including hysteresis operating voltage range.
(*2)
EFFI={ ( output voltage×output current ) / ( input voltage×input current) }×100
(*3)
ON resistance (Ω)=(VIN - Lx pin measurement voltage) / 100mA
(*4)
Design value
(*5)
When temperature is high, a current of approximately 10μA (maximum) may leak.
(*6)
Time until it short-circuits VOUT with GND via 1Ω of resistor from an operational state and is set to Lx=0V from current limit pulse generating.
(*7)
When VIN is less than 2.4V, limit current may not be reached because voltage falls caused by ON resistance.
(*8)
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.
(*9)
Current limit denotes the level of detection at peak of coil current.
(*10)
“H”=VIN ~ VIN-1.2V, “L”=+0.1V ~ -0.1V
(*11)
IPFM and DTYLIMIT_PFM are defined only for the XCL202 series which have PFM control function. (Not for the XCL201 series)
5/22
XCL201/XCL202 Series
■ELECTRICAL CHARACTERISTICS (Continued)
The value and conditions are depends on setting output voltage.
●PFM Switching Current (IPFM) (XCL202)
NOMINAL OUTPUT VOLTAGE
MIN.
0.8V≦VOUT(T) ≦1.2V
1.2V＜VOUT(T)＜1.8V
1.8V≦VOUT(T)≦4.0V
140mA
130mA
120mA
TYP.
MAX.
180mA
170mA
160mA
240mA
220mA
200mA
●PFM Duty Limit DTYLIMIT_PFM (XCL202)
SETTING VOLTAGE
CONDITIONS
0.8V≦VOUT(T)＜1.0V
1.0V≦VOUT(T)≦4.0V
VCE=VIN=2.0V, IOUT=1mA
VCE=VIN=VOUT(T)+0.5V, IOUT=1mA
●Soft-Start Time tSS
SERIES
XCL201B
XCL202B
6/22
OUTPUT VOLTAGE
MIN.
TYP.
MAX.
0.8V≦VOUT(T)＜1.5V
-
0.25ms
0.40ms
1.5V≦VOUT(T)＜1.8V
-
0.32ms
0.50ms
1.8V≦VOUT(T)＜2.5V
-
0.28ms
0.40ms
2.5V≦VOUT(T)≦4.0V
-
0.32ms
0.50ms
0.8V≦VOUT(T)＜2.5V
-
0.28ms
0.40ms
2.5V≦VOUT(T)≦4.0V
-
0.32ms
0.50ms
XCL201/XCL202
Series
■TEST CIRCUITS
Wave Form Measure Point
< Circuit No.1 >
L1
A
VIN
A
Lx
CE
CIN
V
VOUT
VSS
< Circuit No.2 >
CL
L2
L1
Lx
VIN
1μF
CE
VOUT
VSS
L2
※ External Components
* External
Components
CIN : 4.7μF(ceramic)
CL
: 10μF(ceramic)
CIN:
4.7μF
(Ceramic)
CL: 10μF (Ceramic)
< Circuit No.3 >
< Circuit No.4 >
Wave Form Measure Point
L1
VIN
CE
1μF
Rpulldown
200Ω
VOUT
VSS
L1
Lx
VIN
Lx
1μF
CE
V
VOUT
VSS
L2
100mA
L2
ON resistance = (VIN-VLx)/100mA
< Circuit No.5 >
< Circuit No.6 >
ILeakH
L1
VIN
Wave Form Measure Point
L1
Lx
A
VIN
Lx
1μF
ICEH
A
ILeakL
CE
1μF
VOUT
VSS
CE
VSS
L2
V
VOUT
L2
ILIM
ICEL
< Circuit No.7 >
< Circuit No.8 >
VIN
ILx
Wave Form Measure Point
L1
L1
Lx
VIN
Lx
A
Ilat
1μF
CE
VOUT
VSS
L2
CE
1uF
< Circuit No.9 >
VOUT
VSS
Rpulldown
1Ω
Wave Form Measure Point
< Circuit No.10 >
L1
A
CIN
L2
VIN
Lx
CE
VOUT
VSS
A
CIN
L
L1
VIN
Lx
CE
L2
VOUT
VSS
L2
CL
V
* External
Components
※ External Components
: 4.7uH(選別品)Parts)
L: 4.7μHL (Screening
CIN : 4.7μF(ceramic)
CIN: 4.7μF
(Ceramic)
CL : 10μF(ceramic)
CL: 10μF (Ceramic)
7/22
XCL201/XCL202 Series
■TYPICAL APPLICATION CIRCUIT
L1
CL
Lx
VIN
Vss
Vss
VOUT
CE
CIN
L2
●External Components
CIN : 10V/4.7μF(Ceramic)
CL : 6.3V/10μF(Ceramic)
NOTE:
The Inductor can be used only for this DC/DC converter.
Please do not use this inductor for the other reasons.
Please use B, X5R, and X7R grades in temperature characteristics for CIN and CL capacitors.
These grade ceramic capacitors minimize capacitance-loss as a function of voltage stress.
8/22
XCL201/XCL202
Series
■OPERATIONAL DESCRIPTION
The XCL201/XCL202 series consists of a reference voltage source, ramp wave circuit, error amplifier, PWM comparator,
phase compensation circuit, output voltage adjustment resistors, P-channel MOSFET driver transistor, N-channel MOSFET
switching transistor for the synchronous switch, current limiter circuit, UVLO circuit with control IC, and an inductor.
(See the block diagram below.)
L2
L1
Inductor
Phase
Compensation
VOUT
R1
CFB
Error
Amp.
FB
Current Feedback
Current Limit
PWM
Comparator
Logic
R2
Synch
Buffer
Drive
Lx
VSHORT
Vref with
Soft Start,
CE
VIN
PWM/PFM
Selector
VSS
UVLO Cmp
R3
VSS
R4
UVLO
Ramp Wave
Generator
OSC
CE
Control
Logic
CE/
CE
Using the error amplifier, the voltage of the internal voltage reference source is compared with the feedback voltage from the
VOUT pin through split resistors, R1 and R2. Phase compensation is performed on the resulting error amplifier output, to input a
signal to the PWM comparator to determine the turn-on time during PWM operation. The PWM comparator compares, in terms
of voltage level, the signal from the error amplifier with the ramp wave from the ramp wave circuit, and delivers the resulting
output to the buffer driver circuit to cause the Lx pin to output a switching duty cycle. This process is continuously performed to
ensure stable output voltage.
The current feedback circuit monitors the P-channel MOS driver transistor current for each switching operation, and modulates
the error amplifier output signal to provide multiple feedback signals. This enables a stable feedback loop even when a low ESR
capacitor such as a ceramic capacitor is used ensuring stable output voltage.
The reference voltage source provides the reference voltage to ensure stable output voltage of the DC/DC converter.
The ramp wave circuit determines switching frequency. The frequency is fixed internally 1.2MHz. Clock pulses generated in this
circuit are used to produce ramp waveforms needed for PWM operation, and to synchronize all the internal circuits.
The error amplifier is designed to monitor output voltage. The amplifier compares the reference voltage with the feedback voltage
divided by the internal split resistors, R1 and R2. When a feedback voltage is lower than the reference voltage, the output voltage
of the error amplifier is increased. The gain and frequency characteristics of the error amplifier output are fixed internally to deliver
an optimized signal to the mixer.
9/22
XCL201/XCL202 Series
■OPERATIONAL DESCRIPTION (Continued)
The current limiter circuit of the XCL201/XCL202 series monitors the current flowing through the P-channel MOS driver transistor
connected to the Lx pin, and features a combination of the current limit mode and the operation suspension mode.
① When the driver current is greater than a specific level, the current limit function operates to turn off the pulses from the Lx pin at
any given timing.
② When the driver transistor is turned off, the limiter circuit is then released from the current limit detection state.
③ At the next pulse, the driver transistor is turned on. However, the transistor is immediately turned off in the case of an over
current state.
④ When the over current state is eliminated, the IC resumes its normal operation.
The IC waits for the over current state to end by repeating the steps ① through ③. If an over current state continues for a few
milliseconds and the above three steps are repeatedly performed, the IC performs the function of latching the OFF state of the
driver transistor, and goes into operation suspension state. Once the IC is in suspension state, operations can be resumed by
either turning the IC off via the CE pin, or by restoring power to the VIN pin. The suspension state does not mean a complete
shutdown, but a state in which pulse output is suspended; therefore, the internal circuitry remains in operation. The current limit
of the XCL201/XCL202 series can be set at 800mA at typical. Depending on the state of the PC Board, latch time may become
longer and latch operation may not work. In order to avoid the effect of noise, an input capacitor is placed as close to the IC as
possible.
Limit < # ms
Limit > # ms
Current Limit LEVEL
ILx
0mA
VOUT
Vss
Lx
VCE
Restart
VIN
The short-circuit protection circuit monitors the internal R1 and R2 divider voltage from the VOUT pin (refer to FB point in the
block diagram shown in the previous page). In case where output is accidentally shorted to the Ground and when the FB point
voltage decreases less than half of the reference voltage (Vref) and a current more than the ILIM flows to the driver transistor,
the short-circuit protection quickly operates to turn off and to latch the driver transistor. In the latch state, the operation can be
resumed by either turning the IC off and on via the CE pin, or by restoring power supply to the VIN pin.
When sharp load transient happens, a voltage drop at the VOUT is propagated to the FB point through CFB, as a result, short
circuit protection may operate in the voltage higher than 1/2 VOUT voltage.
When the VIN pin voltage becomes 1.4V or lower, the P-channel output driver transistor is forced OFF to prevent false pulse
output caused by unstable operation of the internal circuitry. When the VIN pin voltage becomes 1.8V or higher, switching operation
takes place. By releasing the UVLO function, the IC performs the soft start function to initiate output startup operation. The soft
start function operates even when the VIN pin voltage falls momentarily below the UVLO operating voltage. The UVLO circuit
does not cause a complete shutdown of the IC, but causes pulse output to be suspended; therefore, the internal circuitry remains
in operation.
10/22
XCL201/XCL202
Series
■OPERATIONAL DESCRIPTION (Continued)
In PFM control operation, until coil current reaches to a specified level (IPFM), the IC keeps the P-ch MOSFET on. In this case,
on-time (tON) that the P-ch MOSFET is kept on can be given by the following formula.
tON = L×IPFM / (VIN－VOUT) →IPFM①
In the PFM control operation, the PFM Duty Limit (DTYLIMIT_PFM) is set to 200% (TYP.). Therefore, under the condition that the
duty increases (e.g. the condition that the step-down ratio is small), it’s possible for P-ch MOSFET to be turned off even when coil current
doesn’t reach to IPFM. →IPFM②
DTYIPFM
最大
制限
LIMIT_PFM
tON
Lx
Lx
fOSC
IPFM
ILx
IPFM
ILx
0mA
0mA
IPFM①
IPFM②
The XCL201/XCL202 series can quickly discharge the electric charge at the output capacitor (CL) when a low signal to the CE
pin which enables a whole IC circuit put into OFF state, is inputted via the N-channel transistor located between the LX pin and
the VSS pin. When the IC is disabled, electric charge at the output capacitor (CL) is quickly discharged so that it may avoid
application malfunction. Discharge time of the output capacitor (CL) is set by the CL auto-discharge resistance (R) and the output
capacitor (CL). By setting time constant of a CL auto-discharge resistance value [R] and an output capacitor value (CL) as
τ(τ=C x R), discharge time of the output voltage after discharge via the N channel transistor is calculated by the following
formula.
V = VOUT(T) x e –t/τ or t=τln (VOUT(T) / V)
V : Output voltage after discharge
VOUT(T) : Output voltage
t: Discharge time,
τ: C x R
C=Capacitance of output capacitor (CL)
R=CL auto-discharge resistance
Output Voltage Discharge Characteristics
RDCHG=300Ω(TYP.)
100
CL=10μF
CL=20μF
CL=50μF
Output Voltage (Relative Value)
100 = Setting Voltage Value
80
60
40
20
0
0
20
40
60
80
100
Discharge Time ｔ(ms)
11/22
XCL201/XCL202 Series
■OPERATIONAL DESCRIPTION (Continued)
The operation of the XCL201/XCL202 series will enter into the shutdown mode when a low level signal is input to the CE pin.
During the shutdown mode, the current consumption of the IC becomes 0μA (TYP.), with a state of high impedance at the Lx pin
and VOUT pin. The IC starts its operation by inputting a high level signal to the CE pin. The input to the CE pin is a CMOS input
and the sink current is 0μA (TYP.).
●XCL201/XCL202 series - Examples of how to use CE pin
VIN
VDD
(A)
VIN
VDD
SW_CE
SW CE
R1
SELECTED STATUS
ON
Stand-by
OFF
Operation
CE
CE
(B)
SW_CE
SELECTED STATUS
ON
Operation
OFF
Stand-by
< IC inside >
< IC inside >
Soft start time is internally set 0.25ms to 0.32ms (TYP). Soft start time is defined as the time to reach 90% of the output
nominal voltage when the CE pin is turned on.
tss
VCE
VCEH
0V
VOUT
90% of setting voltage
0V
■FUNCTION CHART
CE
VOLTAGE
LEVEL
H Level (*1)
L Level (*2)
OPERATIONAL STATES
XCL201
XCL202
Synchronous
Synchronous
PWM Fixed Control
PWM/PFM Automatic Switching
Stand-by
Stand-by
* CE pin voltage level range
(*1)
H level: 0.65V
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