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Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator Plus Voltage Detector Step-Down DC/DC Converter's Output Connected In Series with LDO Regulator High Efficiency, Low Noise Regulated Output SOP-8 Package for High Current Small-Footprint Output Current DC/DC:800mA, VR: 400mA Ceramic Capacitor Compatible (Low ESR capacitors)
APPLICATIONS
CD-R / RW, DVD HDD PDAs, portable communication modem Cellular phones Palmtop computers Cameras, video recorders
GENERAL DESCRIPTION
FEATURES
Input Voltage Range : 2.4V ~ 6.0V Low ESR Capacitor : Ceramic capacitor compatible (Low ESR Capacitors) VD Function : Detects output voltage from the VDOUT pin while sensing either VDD, DCOUT, or VROUT internally. N-ch open drain output Output Voltage Range : 1.6V ~ 4.0V (Accuracy 2%) Output Current : 800mA Controls : PWM Control, PWM, PWM/PFM Automatic Switching External Oscillation Frequency : 300kHz, 600kHz, 1.2MHz Output Voltage Range : 0.9V ~ 4.0V (Accuracy2%) Current Limit : 600mA Dropout Voltage : 160mV @ IOUT=200mA (VOUT=2.8V) High Ripple Rejection : 60dB @1kHz (VOUT=2.8V)
The XC9510 series consists of a step-down DC/DC converter and a high-speed LDO regulator connected in series with the DC/DC converter's output. A voltage detector is also built-in. A highly efficient, low noise output is possible since the regulator is stepped-down further from the DC/DC output. The DC/DC converter block incorporates a P-channel driver transistor and a synchronous N-channel switching transistor. With an external coil, diode and two capacitors, the XC9510 can deliver output currents up to 800mA at efficiencies over 90%. The XC9510 is designed for use with small ceramic capacitors. A choice of three switching frequencies are available, 300 kHz, 600 kHz, and 1.2 MHz. Output voltage settings for the DC/DC is set-up internally in 100mV steps within the range of 1.6V to 4.0V(2.0%) and for the VR are set-up internally within the range of 0.9V to 4.0V (2.0%). For the VD, the range is of 0.9V to 5.0V (2.0%). The soft start time of the series is internally set to 5ms. 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 1.4 V or lower. The operational states of the DC/DC and the regulator blocks can be changed by inputting three kinds of voltage level via the CE/MODE pin. The functions of the MODE pin can be selected via the external control pin to switch the DC/DC control mode and the disable pin to shut down the regulator block.
TYPICAL PERFORMANCE CHARACTERISTICS TYPICAL APPLICATION CIRCUIT
XC9510 ETR1007_001.doc
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XC9510 Series
PIN CONFIGURATION
SOP-8 (TOP VIEW)
PIN ASSIGNMENT
PIN NUMBER 1 2 3 4 5 6 7 8 PIN NAME PGND CE/MODE VDD VDOUT AGND VROUT DCOUT LX FUNCTION Power Ground Chip Enable / MODE Switch Power Supply VD Output Analog Ground VR Output DC/DC Output Switch
PRODUCT CLASSIFICATION
Ordering Information XC9510
DESIGNATOR
The input for the voltage regulator block comes from the DC/DC.
DESCRIPTION SYMBOL As chart below Internal standard 3 6 C S R L :: Setting voltage and specifications of each DC/DC, VR, and VD Based on the internal standard) : 300kHz : 600kHz : 1.2MHz : SOP-8 : Embossed Tape, standard feed : Embossed Tape, reverse feed DESCRIPTION
Control Methods And The VD Sense Pin Setting Voltage & Specifications DC/DC Oscillation Frequency Package Device Orientation

Control Methods, CE/MODE Pin, VDSENSE Pin SERIES TYPE A B C D E F H K L DC/DC CONTROL METHODS CE="VCEH" LEVEL CE="VCEM" LEVEL DC/DC: ON VR: ON VD: ON PWM Control CE="VCEL" LEVEL DC/DC: OFF VR: OFF VD: ON DC/DC: OFF VR: OFF VD: ON DC/DC: OFF VR: OFF VD: ON VD SENSE PIN VDD DCOUT VROUT VDD DCOUT VROUT VDD DCOUT VROUT
PWM Control DC/DC: ON VR: OFF VD: ON PFM / PWM Automatic Switch
XC9510
PWM, PFM/PWM Manual Switch
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XC9510
Series
PACKAGING INFORMATION
SOP-8
SOP-8 (TOP VIEW)
MARKING RULE
SOP-8
Represents product series
MARK 1 0
PRODUCT SERIES
XC9510****S*
Represents DC/DC control methods, CE/MODE pins and VD sense pin
MARK
A B C D E F H K L PWM,PFM/PWM Manual Switch PFM/PWM Auto Switch PWM Control PWM Control VR:OFF VR:ON DC/DC:OFF VR:OFF VD:ON DC/DC CONTROL CE/MODE PIN (H level) CE/MODE PIN (M level) CE/MODE PIN (L level) VD SENSE PRODUCT SERIES VDD DCOUT VROUT VDD DCOUT VROUT VDD DCOUT VROUT XC9510A***S* XC9510B***S* XC9510C***S* XC9510D***S* XC9510E***S* XC9510F***S* XC9510H***S* XC9510K***S* XC9510L***S*
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XC9510 Series
MARKING RULE (Continued)
Represents detect voltage DC/DC,VR and VD
ex) MARK 1 3 DC/DC 3.3V VR 1.8V VD 4.0V
PRODUCT SERIES
XC9510*13*S*
Represents oscillation frequency.
MARK 3 6 C OSCILLATION FREQUENCY 300kHz 600kHz 1.2MHz PRODUCT SERIES XC9510***3A* XC9510***6A* XC9510***CA*
Represents last digit of production year.
ex) MARK 3 4 PRODUCTION YEAR 2003 2004
Represents production lot number 0 to 9,A to Z reverse character 0 to 9, A to Z repeated (G,I,J,O,Q,W excepted) Note: No character inversion used
BLOCK DIAGRAM
* Diodes shown in the above circuit are protective diodes.
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XC9510
Series
ABSOLUTE MAXIMUM RATINGS
PARAMETER VDD Pin Voltage DCOUT Pin Voltage VROUT Pin Voltage VROUT Pin Current VDOUT Pin Voltage VDOUT Pin Current Lx Pin Voltage Lx Pin Current CE/MODE Pin Voltage Power Dissipation SOP-8 SYMBOL VDD DCOUT VROUT IROUT VDOUT IVD Lx ILx CE/MODE Pd Topr Tstg RATINGS - 0.3 ~ 6.5 - 0.3 ~ VDD + 0.3 - 0.3 ~ VDD + 0.3 800 - 0.3 ~ VDD + 0.3 50 - 0.3 ~ VDD + 0.3 1300 - 0.3 ~ VDD + 0.3 650* - 40 ~ + 85 - 55 ~ + 125 V V V
Ta = 25 UNIT
mA V mA V mA V mW
Operating Temperature Range Storage Temperature Range (*) When PC board mounted.
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XC9510 Series
ELECTRICAL CHARACTERISTICS
XC9510xxxCSx
Common Characteristics
PARAMETER Supply Current 1 Supply Current 2 Stand-by Current (*1) Input Voltage Range CE `H' Level Voltage *XC9510D/E/F CE `H' Level Voltage *XC9510H/K/L CE `M' Level Voltage CE `L' Level Voltage CE `H' Level Current CE `L' Level Current SYMBOL IDD1 IDD2 ISTB VIN VCEH VCEH VCEM VCEL ICEH ICEL CONDITIONS VIN=CE=DCOUT=5.0V VIN=CE=5.0V, DCOUT=0V VIN=6.5V, CE=0V MIN. 2.4 VDD-0.3 VDD-0.3 0.6 VSS - 0.1 - 0.1 TYP. 250 300 3.0 MAX. 310 360 7.0 6.0 VDD VDD VDD-1.2 0.25 0.1 0.1 UNITS A A A V V V V V A A Topr=25 CIRCUIT 1 1 1 2 3 3 3 1 1 Topr=25 CONDITIONS VIN=CE=DCOUT=5.0V VIN=CE=5.0V, DCOUT=0V VIN=CE=DCOUT=5.0V VIN=CE=5.0V, DCOUT=0V Connected to the external components, IDOUT=30mA Connected to the external components, IDOUT=10mA DCOUT=0V DCOUT=VIN Connected to the external components, No load Connected to the external components DCOUT=0V, LX=VIN-0.05V Connected to the external components, VIN=5.0V VIN=LX=6.0V, CE=0V VIN=6.0V, LX=CE=0V Connected to the external components Connected to the external components, IDOUT=100mA IDOUT=30mA -40Topr85 Connected to the external components, CE=0V VIN, IDOUT=1mA Connected to the external components, VIN=CE=5.0V, Short DCOUT by 1resistor MIN. 2.156 1.02 100 21 1.00 800 1.0 2 TYP. 200 250 250 300 2.200 1.20 30 1.40 0.5 0.5 0.05 0.05 1.1 90 +100 5 8 MAX. 280 330 310 360 2.244 1.38 0 38 1.78 0.9 0.9 1.00 1.00 10 25 UNITS A A A A V MHz % % % V A A mA A % ppm/ mS mS CIRCUIT 1 1 1 1 3 3 4 4 3 3 5 3 11 11 3 6 3 3 3 10
DC/DC Converter (2.2V product)
PARAMETER Supply Current 1 *XC9510D/E/F Supply Current 2 *XC9510D/E/F PFM Supply Current 1 *XC9510H/K/L PFM Supply Current 2 *XC9510H/K/L Output Voltage Oscillation Frequency Maximum Duty Ratio Minimum Duty Ratio PFM Duty Ratio U.V.L.O. Voltage (*2) LX SW `High' ON Resistance (*3) LX SW `Low' ON Resistance LX SW `High' Leak Current (*12) LX SW `Low' Leak Current (*12) Maximum Output Current Current Limit (*9) Efficiency (*4) Output Voltage Temperature Characteristics Soft-Start Time Latch Time (*5, 10) SYMBOL IDD_DC1 IDD_DC2 IDD_PFM1 IDD_PFM2 DCOUT(E) FOSC MAXDUTY MINDUTY PFMDUTY VUVLO RLXH RLXL IleakH IleakL Imax1 Ilim1 EFFI DCOUT ToprDCOUT TSS Tlat
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XC9510
Series
ELECTRICAL CHARACTERISTICS (Continued)
XC9510xxxCSx (Continued)
Regulator (1.8V product)
PARAMETER Output Voltage Maximum Output Current Load Regulation Dropout Voltage 1 (*6) Dropout Voltage 2 Line Regulation Current Limit Short-Circuit Current Ripple Rejection Rate Output Voltage Temperature Characteristics SYMBOL VROUT(E) Imax2 VROUT Vdif 1 Vdif 2 VROUT VINVROUT Ilim2 Ishort PSRR VROUT ToprVROUT 1mAIROUT100mA IROUT=100mA IROUT=200mA IROUT=30mA VROUT(T)+1VVIN6V VROUT=VROUT(E) x 0.9 VROUT=VSS VIN={VOUT(T)+1.0} VDC+0.5Vp-pAC, IROUT=30mA, f=1kHz IROUT=30mA -40Topr85 CONDITIONS IROUT=30mA MIN. 1.764 400 480 TYP. 1.800 15 100 200 0.05 600 30 60 +100 MAX. 1.836 50 200 400 0.25 V mA mV mV mV %/V mA mA dB ppm/ Topr=25 UNITS CIRCUIT 2 2 2 2 2 2 7 7 12 2
Detector (2.7V product)
PARAMETER Detect Voltage Hysteresis Range VD Output Current Output Voltage Temperature Characteristics SYMBOL VDF(E) VHYS IVD VDF ToprVDF CE=0V VHYS=[VDR(E)
(*11)
CONDITIONS - VDF(E)] / VDF(E) x 100
MIN. 2.646 2 1 -
TYP. 2.700 5 +100
MAX. 2.754 8 -
UNITS CIRCUIT V % mA ppm/ 8 8 9 8
VDOUT=0.5V, CE=0V -40Topr85
Test conditions: Unless otherwise stated: DC/DC : VIN=3.6V [@ DCOUT:2.2V] VR: VIN = 2.8V (VIN=VROUT(T) + 1.0V) VD: VIN=5.0V Common conditions for all test items: CE=VIN, MODE=0V * VROUT(T) : Setting output voltage NOTE: *1 : Including VD supply current (VD operates when in stand-by mode.) *2 : Including hysteresis operating voltage range. *3 : ON resistance ()= 0.05 (V) / ILX (A) *4 : EFFI = { ( Output Voltage x Output Current ) / ( Input Voltage x Input Current) } x 100 *5 : Time until it short-circuits DCOUT with GND through 1of resistance from a state of operation and is set to DCOUT=0V from current limit pulse generating. *6 : Vdif = (VIN1
(*7)
- VROUT1
(*8)
)
*7 : VIN 1 = The input voltage when VROUT1 appears as input voltage is gradually decreased. *8 : VROUT1 = A voltage equal to 98% of the output voltage whenever an amply stabilized IOUT {VROUT(T) + 1.0V} is input. *9 : Current limit = When VIN is low, limit current may not be reached because of voltage falls caused by ON resistance or serial resistance of coils. *10: Integral latch circuit=latch time may become longer and latch operation may not work when VIN is 3.0V or more. *11: VDR(E) = VD release voltage *12: When temperature is high, a current of approximately 5.0A (maximum) may leak.
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XC9510 Series
TEST CIRCUITS
Circuit 1 Supply Current, Stand-by Current, CE Current Circuit 2 Output Voltage (VR), Load Regulation, Dropout Voltage, Maximum Output Current, (MODE Voltage)
1 2 3
PGND CE/ MODE VDD VDOUT
LX DCOUT VROUT AGND
8 DCOUT : VIN or GND 7 6 5
CE/MODE : VIN or VIN-1.2V or GND
1 2 3 4
PGND CE/ MODE VDD VDOUT
LX DCOUT VROUT AGND
8 7 6 5
A
A
4
V
V
IROUT
CIN : 1.0uF (ceramic)
CIN : 4.7uF (ceramic) CL:4.7uF(ceramic, 10uF(ceramic, IROUT<300mA) IROUT>300mA)
Circuit 3
Output Voltage (DC/DC) Oscillation Frequency, U.V.L.O. Voltage, Soft-start Time, CE Voltage, Maximum Output Current, Efficiency, (PFM Duty Cycle), (MODE Voltage)
Circuit 4 Minimum Duty Cycle, Maximum Duty Cycle
Probe 1 2 3 4 PGND CE/ MODE VDD VDOUT LX DCOUT VROUT AGND 8 L 7 6 5
CE : VIN 1 2 3 PGND CE/ MODE VDD VDOUT LX DCOUT VROUT AGND 8 7 6 5
Probe
V
IDOUT
4
200
V
V
CIN : 4.7uF (ceramic) Fosc 300kHz 600kHz 1.2MHz
CL : 10uF (ceramic) L 22uH(CDRH6D38, SUMIDA) 10uH(CDRH5D28, SUMIDA) 4.7uH(CDRH4D28C, SUMIDA)
CIN : 1.0uF(ceramic)
Circuit 5
Lx ON Resistance
Circuit 6
Current Limit 1 (DC/DC)
Probe
1 CE : VIN 2 3 4 PGND CE/ MODE VDD VDOUT LX DCOUT VROUT AGND 8 7 6 5
A
CE : VIN
1 2 3 4
PGND CE/ MODE VDD VDOUT
LX DCOUT VROUT AGND
8 7 6 5
A
ILX
V
CIN : 1.0uF (ceramic)
CIN : 4.7uF (ceramic)
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Series
TEST CIRCUITS (Continued)
Circuit 7 Current Limit 2 (VR), Short Circuit Current (VR) Circuit 8 Detect Voltage, Release Voltage (Hysteresis Range)
VD_SENSE* (DCOUT or VROUT)
1 CE/MODE : VSS 2 3 200k 4
PGND CE/ MODE VDD VDOUT
LX DCOUT VROUT AGND
8 7 6 5
V
CIN: 1uF
V
* For the measurement of the VDD_Sense products, the input voltage was controlled.
Circuit 9
VD Output Current
Circuit 10
Latch Time
VD_SENSE* (DCOUT or VROUT) CE : VSS
L
1 2 3 PGND CE/ MODE VDD VDOUT LX DCOUT VROUT AGND 8 7 6 5
1 2 3 4
PGND CE/ MODE VDD VDOUT
LX DCOUT VROUT AGND
8 7 6 5
A V
4
V
1
V
CIN : 1uF (ceramic)
CIN : 4.7uF (ceramic) Fosc 300kHz 600kHz 1.2MHz
CL : 10uF (ceramic) L 22uH(CDRH6D38, SUMIDA) 10uH(CDRH5D28, SUMIDA) 4.7uH(CDRH4D28C, SUMIDA)
* For the measurement of the VDD_Sense products, the input voltage was controlled.
Circuit 11
Off-Leak
Circuit 12
Ripple Rejection Rate
1 CE/MODE : VSS 2 3
PGND CE/ MODE VDD VDOUT
LX DCOUT VROUT AGND
8 7 6 5
A
CE/MODE : VIN or VIN-1.2V or GND
1 2
PGND CE/ MODE VDD VDOUT
LX DCOUT VROUT AGND
8 7 6 5
A
3 4
A V
4
~
V
V
IROUT
CIN : 1.0uF (ceramic)
CIN : 4.7uF (ceramic) CL:4.7uF(ceramic, 10uF(ceramic, IROUT<300mA) IROUT>300mA)
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XC9510 Series
TYPICAL APPLICATION CIRCUIT
FOSC 1.2MHz 600kHz 300kHz L 4.7H (CDRH4D28C, SUMIDA) 10H (CDRH5D28, SUMIDA) 22H (CDRH6D28, SUMIDA)
SOP-8 (TOP VIEW)
CIN 4.7F(ceramic, TAIYO YUDEN)
CL1 10F(ceramic, TAIYO YUDEN) IROUT<300mA IROUT>300mA
CL2 *
2
4.7F (ceramic, TAIYO YUDEN) 10F (ceramic, TAIYO YUDEN)
*1 The DC/DC converter of the XC9510 series automatically switches between synchronous / non-synchronous. diode is not normally needed. light load while in non-synchronous operation, please connect a Schottky diode externally.
The Schottky
However, in cases where high efficiency is required when using the DC/DC converter during in the
*2 Please be noted that the recommend value above of the CL2 may be changed depending on the input voltage value and setting voltage value.
OPERATIONAL EXPLANATION
The XC9510 series consists of a synchronous step-down DC/DC converter, a high speed LDO voltage regulator, and a voltage detector. Since the LDO voltage regulator is stepped-down from the DC/DC's output,high efficiency and low noise is possible even at lower output voltages. DC/DC Converter The series consists of a reference voltage source, ramp wave circuit, error amplifier, PWM comparator, phase compensation circuit, output voltage adjustment resistors, driver transistor, synchronous switch, current limiter circuit, U.V.L.O. circuit and others. The series ICs compare, using the error amplifier, the voltage of the internal voltage reference source with the feedback voltage from the VOUT pin through split resistors. 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 and can be selected from 300kHz, 600 kHz and 1.2 MHz. 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. When a voltage lower than the reference voltage is fed back, the output voltage of the error amplifier increases. The gain and frequency characteristics of the error amplifier output are fixed internally to deliver an optimized signal to the mixer.
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XC9510
Series
OPERATIONAL EXPLANATION (Continued)
The XC9510A to F series are PWM control, while the XC9510H to L series can be automatically switched between PWM control and PWM/PFM control. The PWM of the XC9510A to F series are controlled on a specified frequency from light loads through the heavy loads. Since the frequency is specified, the composition of a noise filter etc. becomes easy. However, the efficiency at the time of the light load may become low. The XC9510H to L series can switch in any timing between PWM control and PWM/PFM automatic switching control. The series cannot control only PFM mode. If needed, the operation can be set on a specified frequency; therefore, the control of the noise etc. is possible and the high efficiency at the time of the light load during PFM control mode is possible. With the automatic PWM/PFM switching control function, the series ICs are automatically switched from PWM control to PFM control mode under light load conditions. If during light load conditions the coil current becomes discontinuous and on-time rate falls lower than 30%, the PFM circuit operates to output a pulse with 30% of a fixed on-time rate from the Lx pin. During PFM operation with this fixed on-time rate, pulses are generated at different frequencies according to conditions of the moment. This causes a reduction in the number of switching operations per unit of time, resulting in efficiency improvement under light load conditions. However, since pulse output frequency is not constant, consideration should be given if a noise filter or the like is needed. Necessary conditions for switching to PFM operation depend on input voltage, load current, coil value and other factors. The XC9510 series automatically switches between synchronous / non-synchronous according to the state of the DC/DC converter. Highly efficient operations are achievable using the synchronous mode while the coil current is in a continuous state. The series enters non-synchronous operation when the built-in N-ch switching transistor for synchronous operation is shutdown which happens when the load current becomes low and the operation changes to a discontinuous state. The IC can operate without an external schottky diode because the parasitic diode in the N-ch switching transistor provides the circuit's step-down operation. However, since Vf of the parasitic diode is a high 0.6V, the efficiency level during non-synchronous operation shows a slight decrease. Please use an external schottky diode if high efficiency is required during light load current. Continuous Mode: Synchronous Discontinuous Mode: Non-Synchronous
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XC9510 Series
OPERATIONAL EXPLANATION (Continued)
The current limiter circuit of the XC9510 series monitors the current flowing through the P-channel MOS driver transistor connected to the Lx pin, and features a combination of the constant-current type current limit mode and the operation suspension mode. When the driver current is greater than a specific level, the constant-current type current limit function operates to turn off the pulses from the Lx pin at any given timing. When the driver transistor is turned off, the limiter circuit is then released from the current limit detection state. 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. 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 through . If an over current state continues for 8msec* 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 mode. Once the IC is in suspension mode, operations can be resumed by either turning the IC off via the CE/MODE pin, or by restoring power to the VIN pin. The suspension mode does not mean a complete shutdown, but a state in which pulse output is suspended; therefore, the internal circuitry remains in operation. The constant-current type current limit of the XC9510 series can be set at 1.1A.
When the VIN pin voltage becomes 1.4 V 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 1.8 V or higher, switching operation takes place. By releasing the U.V.L.O. 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 U.V.L.O. operating voltage. The U.V.L.O. circuit does not cause a complete shutdown of the IC, but causes pulse output to be suspended; therefore, the internal circuitry remains in operation. High Speed LDO Voltage Regulator The voltage regulator block of the XC9510 series consists of a reference voltage source, error amplifier, and current limiter circuit.The voltage divided by split resistors is compared with the internal reference voltage by the error amplifier. The P-channel MOSFET, which is connected to the VROUT pin, is then driven by the subsequent output signal. The output voltage at the VROUT pin is controlled and stabilized by a system of negative feedback. A stable output voltage is achievable even if used with low ESR capacitors as a phase compensation circuit is built-in. The reference voltage source provides the reference voltage to ensure stable output voltage of the regulator. The error amplifier compares the reference voltage with the signal from VROUT, and the amplifier controls the output of the P-ch driver transistor. The voltage regulator block includes a combination of a constant current limiter circuit and a foldback circuit. When the load current reaches the current limit level, the current limiter circuit operates and the output voltage of the voltage regulator block drops. As a result of this drop in output voltage, the foldback circuit operates, output voltage drops further and the load current decreases. When the VROUT and GND pin are shorted, the load current of about 30mA flows.
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OPERATIONAL EXPLANATION (Continued)
Voltage Detector The detector block of the XC9510 series detects output voltage from the VDOUT pin while sensing either VDD, DCOUT, or VROUT internally. (N-channel Open Drain Type) < CE / MODE Pin Function> The operation of the XC9510 series' DC/DC converter block and voltage regulator block will enter into the shut down mode when a low level signal is input to the CE/MODE pin. During the shut down mode, the current consumption occurs only in the detector and is 3.0A (TYP.), with a state of high impedance at the Lx pin and DCOUT pin. The IC starts its operation by inputting a high level signal or a middle level signal to the CE/MODE pin. The input to the CE/MODE pin is a CMOS input and the sink current is 0A (TYP.). The operation of the XC9510D to F series' voltage detector block will enter into stand-by mode when a high level signal is input to the CE/MODE pin. The voltage regulator block will operate when a middle level signal is input. But when a low level signal is input, the voltage regulator block will enter into stand-by mode. With the XC9510H to L series control can be PWM control when the CE/MODE pin is 'M' level and PWM/PFM automatic switching control when the CE/MODE pin is 'H' level.
NOTES ON USE
Application Information 1. The XC9510 series is designed for use with ceramic output capacitors. If, however, the potential difference between dropout voltage or output current is too large, a ceramic capacitor may fail to absorb the resulting high switching energy and oscillation could occur on the output. If the input-output potential difference is large, connect an electrolytic capacitor in parallel to compensate for insufficient capacitance. 2. Spike noise and ripple voltage arise in a switching regulator as with a DC/DC converter. These are greatly influenced by external
component selection, such as the coil inductance, capacitance values, and board layout of external components. has been completed, verification with actual components should be done. Once the design
3. When the difference between VIN and VOUT is large in PWM control, very narrow pulses will be outputted, and there is the possibility that some cycles may be skipped completely. 4. When the difference between VIN and VOUT is small, and the load current is heavy, very wide pulses will be outputted and there is the possibility that some cycles may be skipped completely: in this case, the Lx pin may not go low at all.
DC/DC Waveform (3.3V, 1.2MHz)
< External Components> L:4.7H(CDRH4D28C,SUMIDA) CIN:4.7F(ceramic) CL:10F(ceramic)
< External Components> L:4.7H(CDRH4D28C,SUMIDA) CIN:4.7F(ceramic) CL:10F(ceramic)
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XC9510 Series
NOTES ON USE (Continued)
Application Information (Continued) 5. The IC's DC/DC converter operates in synchronous mode when the coil current is in a continuous state and non-synchronous mode when the coil current is in a discontinuous state. In order to maintain the load current value when synchronous switches to non-synchronous and vise versa, a ripple voltage may increase because of the repetition of switching between synchronous and non-synchronous. When this state continues, the increase in the ripple voltage stops. To reduce the ripple voltage, please increase the load capacitance value or use a schottky diode externally. When the current used becomes close to the value of the load current when synchronous switches to non- synchronous and vise versa, the switching current value can be changed by changing the coil inductance value. In case changes to coil inductance are to values other than the recommended coil inductance values, verification with actual components should be done. Ics = (VIN - DCOUT) x OnDuty / (L x Fosc) Ics: Switching current from synchronous rectification to non-synchronous rectification . OnDuty: OnDuty ratio of P-ch driver transistor ( =.step down ratio : DCOUT / VIN) L: Coil inductance value Fosc: Oscillation frequency IDOUT: The DC/DC load current
(the sum of the DC/DC's and the regulator's load if the regulator has load.)
6. When the XC9510H to L series operates in PWM/PFM automatic switching control mode, the reverse current may become quite high around the load current value when synchronous switches to non-synchronous and vise versa (also refer to no. 5 above). Under this condition, switching synchronous rectification and non-synchronous rectification may be repeated because of the reverse current, and the ripple voltage may be increased to 100mV or more. The reverse current is the current that flows in the PGND direction through the N-ch driver transistor from the coil. The conditions which cause this operation are as follows. PFM Duty < Step down ratio = DCOUT / VIN x 100 (%) PFM Duty: 30% (TYP.) Please switch to PWM control via the MODE function in cases where the load current value of the DC/DC converter is close to synchronous.
DC/DC Waveform (1.8V, 600kHz) @ VIN=6.0V
< External Components> L:10H(CDRH5D28C,SUMIDA) CIN:4.7F(ceramic) CL:10F(ceramic) Step down ratio : 1.8V / 6.0V = 30%
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XC9510
Series
NOTES ON USE (Continued)
Application Information (Continued) 7. With the DC/DC converter of the IC, the peak current of the coil is controlled by the current limit circuit. Since the peak current increases when dropout voltage or load current is high, current limit starts operating, and this can lead to instability. When peak current becomes high, please adjust the coil inductance value and fully check the circuit operation. In addition, please calculate the peak current according to the following formula: Peak current: Ipk = (VIN - DCOUT) x OnDuty / (2 x L x Fosc) + IDOUT 8. When the peak current, which exceeds limit current flows within the specified time, the built-in driver transistor is turned off (the integral latch circuit). During the time until it detects limit current and before the built-in transistor can be turned off, the current for limit current flows; therefore, care must be taken when selecting the rating for the coil or the Schottky diode. 9. When VIN is low, limit current may not be reached because of voltage falls caused by ON resistance or serial resistance of the coil. 10. In the integral latch circuit, latch time may become longer and latch operation may not work when VIN is 3.0V or more. 11. Use of the IC at voltages below the recommended voltage range may lead to instability. 12. This IC and the external components should be used within the stated absolute maximum ratings in order to prevent damage to the device.
13.
Since the DC/DC converter and the regulator of the XC9510 series are connected in series, the sum of the output current (IDOUT) of the DC/DC and the output current (IROUT) of the VR makes the current flows inside the DC/DC converter. Please be careful of the power dissipation when in use. Please calculate power dissipation by using the following formula. Pd=PdDC/DC + PdVR DC/DC power dissipation (when in synchronous operation) : PdDC/DC = IDOUT2 x RON VR power dissipation: PdVR=(DCOUT - VROUT) x IROUT RON: ON resistance of the built-in driver transistor to the DC/DC (= 0.5) RON=Rpon x P-chOnDuty / 100 + Rnon x (1 - P-chOnDuty / 100)
14. The voltage detector circuit built-in the XC9510 series internally monitor the VDD pin voltage, the DC/DC output pin voltage and VR output pin voltage. For the XC9510B/C/E/F/K/L series, which voltage detector circuit monitors the DC/DC output pin voltage and the VR output pin voltage, please determine the detect voltage value (VDF) by the following equation. VDF(Setting voltage on both the DCOUT voltage and the VROUT voltage)x85%* * An assumed value of tolerance among the DCOUT voltage, the VROUT voltage, and the VD release voltage (The VD detect voltage and hysteresis range).
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XC9510 Series
NOTES ON USE (Continued)
Instructions on Pattern Layout 1. In order to stabilize VIN's voltage level, we recommend that a by-pass capacitor (CIN) be connected as close as possible to the VDD & AGND pins. This IC is the composite IC of the DC/DC converter and regulator. Fluctuation of the VIN's voltage level causes mutual interference. 2. Please mount each external component as close to the IC as possible. 3. Wire external components as close to the IC as possible and use thick, short connecting traces to reduce the circuit impedance. 4. Make sure that the PCB GND traces are as thick as possible, as variations in ground potential caused by high ground currents at the time of switching may result in instability of the DC/DC converter and have adverse influence on the regulator output. 5. If using a Schottky diode, please connect the anode side to the AGND pin through CIN. Characteristic degradation caused by the noise may occur depending on the arrangement of the Schottky diode.
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS
(A) DC/DC CONVERTER (1) Efficiency vs. Output Current
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued) (2) Output Voltage vs. Output Current
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued) (3) Output Voltage vs. Ripple Voltage
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued) (4) Output Voltage vs. Ambient Temperature
(5) Soft Start Time vs. Ambient Temperature
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued) (6) DC/DC Supply Current vs. Ambient Temperature(VR:Shutdown)*
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued) (7) LX P-ch/N-ch On Resistance vs. Input Voltage
(8) Oscillation Frequency vs. Ambient Temperature
(9) U.V.L.O. Voltage vs. Ambient Temperature
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued) (10-2) DC/DC Load Transient Response (*DCOUT:3.3V FOSC:1.2MHz) (a) PWM Control
(b) PWM/PFM Automatic Switching Control* (*XC9510H/K/L Series Only)
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued) (10-3) DC/DC Load Transient Response (*DCOUT:1.8V FOSC:600kHz) (a) PWM Control
(b) PWM/PFM Automatic Switching Control* (*XC9510H/K/L Series Only)
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued) (10-4) DC/DC Load Transient Response (*DCOUT:3.3V FOSC:600kHz) (a) PWM control
(b) PWM/PFM Automatic Switching Control* (*XC9510H/K/L Series Only)
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (1) Output Voltage VS. Input Voltage
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued) (2) Output Voltage VS. Output Current (Current Limit)
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued) (3) Dropout Voltage VS. Output Current
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued) (4) Output Voltage VS. Output Current
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued) (5) Output Voltage VS. Ambient Temperature
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued) (6) Ripple Rejection Ratio VS. Ripple Frequency
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued) (7) VR LOAD TRANSIENT RESPONSE
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(C) VOLTAGE DETECTOR (1) Output Current VS. Input Voltage
(2) Detect Voltage VS. Input Voltage
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(C) VOLTAGE DETECTOR (Continued) (3) Detect Voltage,Release Voltage VS. Ambient Temperature
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XC9510
Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(D) COMMON (1) Supply Current VS. Ambient Temperature (DC/DC & VR & VD)
(2) Shutdown Current VS. Input Voltage
(3) Shutdown Current VS. Ambient Temperature
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XC9510 Series
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(D) COMMON (Continued) (4) CE/MODE Pin Threshold Voltage*
Ambient Temperature:Ta()
* Control Methods, CE/MODE Pin, VDSENSE Pin
SERIES TYPE A B C D E F H K L DC/DC CONTROL METHODS CE="VCEH" LEVEL PWM Control DC/DC: ON VR: OFF VD: ON PFM / PWM Automatic Switch CE="VCEM" LEVEL DC/DC: ON VR: ON VD: ON PWM Control CE="VCEL" LEVEL DC/DC: OFF VR: OFF VD: ON DC/DC: OFF VR: OFF VD: ON DC/DC: OFF VR: OFF VD: ON VD SENSE PIN VDD DCOUT VROUT VDD DCOUT VROUT VDD DCOUT VROUT
XC9510
PWM, PFM/PWM Manual Switch
1386

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