XCL201B1L1ER-G

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