◆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)
■GENERAL DESCRIPTION
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.
■APPLICATIONS
●CD-R / RW, DVD
●HDD
●PDAs, portable communication modem
●Cellular phones
●Palmtop computers
●Cameras, video recorders
■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
<DC/DC Converter Block>
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
<Regulator Block>
Output Voltage Range : 0.9V ~ 4.0V (Accuracy±2%)
Current Limit
: 600mA
Dropout Voltage
: 160mV @ IOUT=200mA
(VOUT=2.8V)
High Ripple Rejection : 60dB @1kHz (VOUT=2.8V)
■TYPICAL PERFORMANCE
CHARACTERISTICS
■TYPICAL APPLICATION CIRCUIT
XC9510 ETR1007_001.doc
1351
XC9510 Series
■PIN CONFIGURATION
SOP-8 (TOP VIEW)
■PIN ASSIGNMENT
PIN NUMBER
PIN NAME
FUNCTION
1
2
3
4
5
6
7
8
PGND
CE/MODE
VDD
VDOUT
AGND
VROUT
DCOUT
LX
Power Ground
Chip Enable / MODE Switch
Power Supply
VD Output
Analog Ground
VR Output
DC/DC Output
Switch
■PRODUCT CLASSIFICATION
●Ordering Information
XC9510①②③④⑤⑥
DESIGNATOR
The input for the voltage regulator block comes from the DC/DC.
DESCRIPTION
SYMBOL
Control Methods And
The VD Sense Pin
Setting Voltage &
Specifications
①
②③
④
DC/DC Oscillation
Frequency
⑤
Package
⑥
Device Orientation
As chart below
Internal
standard
3
6
C
S
R
L
DESCRIPTION
:: 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
●Control Methods, CE/MODE Pin, VDSENSE Pin
SERIES
TYPE
XC9510
A
B
C
D
E
F
H
K
L
1352
DC/DC
CONTROL
METHODS
PWM Control
PWM,
PFM/PWM
Manual Switch
CE=”VCEH” LEVEL
CE=”VCEM”
LEVEL
CE=”VCEL”
LEVEL
VD SENSE
PIN
-
-
DC/DC: OFF
VR: OFF
VD: ON
DC/DC: ON
VR: OFF
VD: ON
DC/DC: ON
VR: ON
VD: ON
DC/DC: OFF
VR: OFF
VD: ON
PFM / PWM
Automatic Switch
PWM Control
DC/DC: OFF
VR: OFF
VD: ON
VDD
DCOUT
VROUT
VDD
DCOUT
VROUT
VDD
DCOUT
VROUT
XC9510
Series
■PACKAGING INFORMATION
●SOP-8
SOP-8
(TOP VIEW)
■MARKING RULE
●SOP-8
①②Represents product series
MARK
①
1
②
0
PRODUCT SERIES
XC9510****S*
③Represents DC/DC control methods, CE/MODE pins and VD sense pin
MARK
DC/DC CONTROL
CE/MODE PIN
(H level)
CE/MODE PIN
(M level)
-
-
CE/MODE PIN
(L level)
A
VDD
B
C
D
PWM Control
VR:OFF
E
VR:ON
F
H
K
L
VD SENSE PRODUCT SERIES
PWM,PFM/PWM
PFM/PWM
Manual Switch
Auto Switch
PWM Control
XC9510A***S*
DCOUT
XC9510B***S*
VROUT
XC9510C***S*
DC/DC:OFF
VDD
XC9510D***S*
VR:OFF
DCOUT
XC9510E***S*
VD:ON
VROUT
XC9510F***S*
VDD
XC9510H***S*
DCOUT
XC9510K***S*
VROUT
XC9510L***S*
1353
XC9510 Series
■MARKING RULE (Continued)
④⑤Represents detect voltage DC/DC,VR and VD
ex)
MARK
④
1
⑤
3
DC/DC
VR
VD
PRODUCT SERIES
3.3V
1.8V
4.0V
XC9510*13*S*
⑥Represents oscillation frequency.
MARK
3
6
C
OSCILLATION FREQUENCY
300kHz
600kHz
PRODUCT SERIES
XC9510***3A*
XC9510***6A*
1.2MHz
XC9510***CA*
⑦Represents last digit of production year.
ex)
MARK
3
4
PRODUCTION YEAR
2003
2004
⑧⑨Represents 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.
1354
XC9510
Series
■ABSOLUTE MAXIMUM RATINGS
Ta = 25℃
PARAMETER
SYMBOL
RATINGS
UNIT
VDD Pin Voltage
VDD
- 0.3 ~ 6.5
V
DCOUT Pin Voltage
DCOUT
- 0.3 ~ VDD + 0.3
V
VROUT Pin Voltage
VROUT
- 0.3 ~ VDD + 0.3
V
VROUT Pin Current
IROUT
800
mA
VDOUT Pin Voltage
VDOUT
- 0.3 ~ VDD + 0.3
V
VDOUT Pin Current
IVD
50
mA
Lx Pin Voltage
Lx
- 0.3 ~ VDD + 0.3
V
Lx Pin Current
ILx
±1300
mA
CE/MODE Pin Voltage
CE/MODE
- 0.3 ~ VDD + 0.3
V
Pd
650*
mW
Operating Temperature Range
Topr
- 40 ~ + 85
℃
Storage Temperature Range
Tstg
- 55 ~ + 125
℃
Power Dissipation
SOP-8
(*) When PC board mounted.
1355
XC9510 Series
■ELECTRICAL CHARACTERISTICS
XC9510xxxCSx
●Common Characteristics
Topr=25℃
PARAMETER
SYMBOL
MAX.
UNITS
CIRCUIT
Supply Current 1
IDD1
VIN=CE=DCOUT=5.0V
-
Supply Current 2
IDD2
VIN=CE=5.0V, DCOUT=0V
-
250
310
μA
1
300
360
μA
Stand-by Current (*1)
ISTB
VIN=6.5V, CE=0V
-
1
3.0
7.0
μA
1
Input Voltage Range
VIN
2.4
-
6.0
V
-
VCEH
VDD-0.3
-
VDD
V
2
VCEH
VDD-0.3
-
VDD
V
3
CE ‘M’ Level Voltage
VCEM
0.6
-
VDD-1.2
V
3
CE ‘H’ Level Voltage
*XC9510D/E/F
CE ‘H’ Level Voltage
*XC9510H/K/L
CONDITIONS
MIN.
TYP.
CE ‘L’ Level Voltage
VCEL
VSS
-
0.25
V
3
CE ‘H’ Level Current
ICEH
- 0.1
-
0.1
μA
1
CE ‘L’ Level Current
ICEL
- 0.1
-
0.1
μA
1
MIN.
TYP.
MAX.
UNITS
CIRCUIT
●DC/DC Converter (2.2V product)
Topr=25℃
PARAMETER
SYMBOL
Supply Current 1 *XC9510D/E/F
IDD_DC1
VIN=CE=DCOUT=5.0V
-
200
280
μA
1
Supply Current 2 *XC9510D/E/F
IDD_DC2
VIN=CE=5.0V, DCOUT=0V
-
250
330
μA
1
IDD_PFM1
VIN=CE=DCOUT=5.0V
-
250
310
μA
1
IDD_PFM2
VIN=CE=5.0V, DCOUT=0V
-
300
360
μA
1
2.156
2.200
2.244
V
3
1.02
1.20
1.38
MHz
3
DCOUT=0V
100
-
-
%
4
DCOUT=VIN
-
-
0
%
4
21
30
38
%
3
1.00
1.40
1.78
V
3
-
0.5
0.9
Ω
5
-
0.5
0.9
Ω
3
-
0.05
1.00
μA
11
11
PFM Supply Current 1
*XC9510H/K/L
PFM Supply Current 2
*XC9510H/K/L
Output Voltage
DCOUT(E)
Oscillation Frequency
FOSC
Maximum Duty Ratio
MAXDUTY
Minimum Duty Ratio
MINDUTY
PFM Duty Ratio
PFMDUTY
U.V.L.O. Voltage (*2)
VUVLO
LX SW ‘High’ ON Resistance
(*3)
RLXH
LX SW ‘Low’ ON Resistance
RLXL
LX SW ‘High’ Leak Current (*12)
IleakH
CONDITIONS
Connected to the external components,
IDOUT=30mA
Connected to the external components,
IDOUT=10mA
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
LX SW ‘Low’ Leak Current (*12)
IleakL
VIN=6.0V, LX=CE=0V
Maximum Output Current
Imax1
Connected to the external components
Current Limit (*9)
Ilim1
Efficiency (*4)
EFFI
Output Voltage
Temperature Characteristics
UDCOUT
UTopr・DCOUT
Soft-Start Time
TSS
Latch Time (*5, 10)
Tlat
1356
Connected to the external components,
IDOUT=100mA
IDOUT=30mA
-40℃≦Topr≦85℃
Connected to the external components,
CE=0VtVIN, IDOUT=1mA
Connected to the external components,
VIN=CE=5.0V, Short DCOUT by 1Ωresistor
-
0.05
1.00
μA
800
-
-
mA
3
1.0
1.1
-
A
6
-
90
-
%
3
-
+100
-
2
5
10
mS
3
-
8
25
mS
10
ppm/
℃
3
XC9510
Series
■ELECTRICAL CHARACTERISTICS (Continued)
XC9510xxxCSx (Continued)
●Regulator (1.8V product)
Topr=25℃
PARAMETER
SYMBOL
CONDITIONS
IROUT=30mA
MIN.
TYP.
MAX.
UNITS CIRCUIT
1.764
1.800
1.836
V
2
400
-
-
mA
2
Output Voltage
VROUT(E)
Maximum Output Current
Imax2
Load Regulation
U VROUT
1mA≦IROUT≦100mA
-
15
50
mV
2
Dropout Voltage 1 (*6)
Vdif 1
IROUT=100mA
-
100
200
mV
2
Dropout Voltage 2
Vdif 2
IROUT=200mA
-
200
400
mV
2
Line Regulation
UVROUT
UVIN・VROUT
IROUT=30mA
VROUT(T)+1V≦VIN≦6V
-
0.05
0.25
%/V
2
Current Limit
Ilim2
VROUT=VROUT(E) x 0.9
480
600
-
mA
7
Short-Circuit Current
Ishort
VROUT=VSS
-
30
-
mA
7
-
60
-
dB
12
-
+100
-
VIN={VOUT(T)+1.0} VDC+0.5Vp-pAC,
Ripple Rejection Rate
PSRR
Output Voltage
UVROUT
UTopr・VROUT
Temperature Characteristics
IROUT=30mA, f=1kHz
IROUT=30mA
-40℃≦Topr≦85℃
ppm/
℃
2
●Detector (2.7V product)
PARAMETER
SYMBOL
Detect Voltage
VDF(E)
CONDITIONS
CE=0V
(*11)
TYP.
MAX.
2.700
2.754
UNITS CIRCUIT
V
8
Hysteresis Range
VHYS
VHYS=[VDR(E)
2
5
8
%
8
VD Output Current
IVD
VDOUT=0.5V, CE=0V
1
-
-
mA
9
Output Voltage
UVDF
UTopr・VDF
-40℃≦Topr≦85℃
-
+100
-
Temperature Characteristics
- VDF(E)] / VDF(E) x 100
MIN.
2.646
ppm/
℃
8
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 (Ω)= 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 1Ωof 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 5.0μA (maximum) may leak.
1357
XC9510 Series
■TEST CIRCUITS
Circuit 1
Supply Current, Stand-by Current, CE Current
1
CE/
MODE
2
3
A
A
LX
PGND
VDD
4
VDOUT
Circuit 2 Output Voltage (VR), Load Regulation, Dropout Voltage,
Maximum Output Current, (MODE Voltage)
8
DCOUT : VIN or GND
CE/MODE : VIN
or VIN-1.2V
or GND
7
DCOUT
VROUT
6
AGND
LX
8
2
CE/
MODE
PGND
DCOUT
7
3
VDD
VROUT
6
4
VDOUT
AGND
5
1
5
V
V
IROUT
CIN : 4.7uF (ceramic)
CIN : 1.0uF (ceramic)
CL:4.7uF(ceramic,
10uF(ceramic,
Circuit 3
IROUT<300mA)
IROUT>300mA)
Circuit 4 Minimum Duty Cycle, Maximum Duty Cycle
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)
Probe
PGND
1
2
3
4
CE/
MODE
VDD
LX
8
DCOUT
7
L
VROUT
VDOUT
Probe
AGND
CE : VIN
LX
8
2
CE/
MODE
DCOUT
7
6
3
VDD
VROUT
6
5
4
VDOUT
AGND
5
V
IDOUT
200Ω
V
V
CL : 10uF
(ceramic)
CIN : 4.7uF (ceramic)
Fosc
300kHz
600kHz
1.2MHz
Circuit 5
PGND
1
CIN : 1.0uF(ceramic)
L
22uH(CDRH6D38, SUMIDA)
10uH(CDRH5D28, SUMIDA)
4.7uH(CDRH4D28C, SUMIDA)
Lx ON Resistance
Circuit 6
Current Limit 1 (DC/DC)
Probe
1
CE : VIN
PGND
LX
8
1
A
CE : VIN
1358
LX
8
2
CE/
MODE
DCOUT
7
6
3
VDD
VROUT
6
5
4
VDOUT
AGND
5
2
CE/
MODE
DCOUT
7
3
VDD
VROUT
4
VDOUT
AGND
V
CIN : 1.0uF (ceramic)
PGND
CIN : 4.7uF (ceramic)
A
ILX
XC9510
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
LX
8
2
CE/
MODE
DCOUT
7
3
VDD
VROUT
6
4
VDOUT
AGND
5
PGND
200k Ω
V
V
CIN:
1uF
* For the measurement of the VDD_Sense products, the
input voltage was controlled.
Circuit 9
VD Output Current
Circuit 10
Latch Time
L
VD_SENSE*
(DCOUT or VROUT)
PGND
1
CE : VSS
A
LX
8
1
PGND
8
2
CE/
MODE
DCOUT
7
2
CE/
MODE
DCOUT
7
3
VDD
VROUT
6
3
VDD
VROUT
6
4
VDOUT
AGND
5
4
VDOUT
AGND
5
V
V
V
1Ω
CL : 10uF
(ceramic)
CIN : 4.7uF
(ceramic)
CIN : 1uF (ceramic)
* For the measurement of the VDD_Sense products, the
input voltage was controlled.
Circuit 11
LX
Off-Leak
Circuit 12
1
CE/MODE : VSS
2
3
A
V
Fosc
300kHz
600kHz
1.2MHz
4
PGND
LX
CE/
MODE
DCOUT
VDD
VROUT
VDOUT
AGND
A
8
Ripple Rejection Rate
CE/MODE : VIN
or VIN-1.2V
or GND
LX
8
2
CE/
MODE
DCOUT
7
3
VDD
VROUT
6
4
VDOUT
AGND
5
1
7
6
5
L
22uH(CDRH6D38, SUMIDA)
10uH(CDRH5D28, SUMIDA)
4.7uH(CDRH4D28C, SUMIDA)
A
~
PGND
V
V
IROUT
CIN : 1.0uF
(ceramic)
CIN : 4.7uF
(ceramic)
CL:4.7uF(ceramic,
10uF(ceramic,
IROUT<300mA)
IROUT>300mA)
1359
XC9510 Series
■TYPICAL APPLICATION CIRCUIT
FOSC
L
1.2MHz
4.7μH (CDRH4D28C, SUMIDA)
600kHz
10μH (CDRH5D28, SUMIDA)
300kHz
22μH (CDRH6D28, SUMIDA)
SOP-8 (TOP VIEW)
CIN
CL1
4.7μF(ceramic, TAIYO YUDEN)
10μF(ceramic, TAIYO YUDEN)
CL2 *
2
IROUT<300mA
4.7μF (ceramic, TAIYO YUDEN)
IROUT>300mA
10μF (ceramic, TAIYO YUDEN)
*1 The DC/DC converter of the XC9510 series automatically switches between synchronous / non-synchronous.
diode is not normally needed.
The Schottky
However, in cases where high efficiency is required when using the DC/DC converter during in the
light load while in non-synchronous operation, please connect a Schottky diode externally.
*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.
<Reference Voltage Source>
The reference voltage source provides the reference voltage to ensure stable output voltage of the DC/DC converter.
<Ramp Wave Circuit>
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.
<Error Amplifier>
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.
1360
XC9510
Series
■OPERATIONAL EXPLANATION (Continued)
<PWM/PFM>
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.
<Synchronous / Non-synchronous>
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
1361
XC9510 Series
■OPERATIONAL EXPLANATION (Continued)
<Current Limit>
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.
① 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.
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 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.
<U.V.L.O. Circuit>
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.
<Reference Voltage Source>
The reference voltage source provides the reference voltage to ensure stable output voltage of the regulator.
<Error Amplifier>
The error amplifier compares the reference voltage with the signal from VROUT, and the amplifier controls the output of
the P-ch driver transistor.
<Current Limit Circuit>
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.
1362
XC9510
Series
■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 3.0μA (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 0μA (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:4.7μH(CDRH4D28C,SUMIDA)
CIN:4.7μF(ceramic)
CL:10μF(ceramic)
< External Components>
L:4.7μH(CDRH4D28C,SUMIDA)
CIN:4.7μF(ceramic)
CL:10μF(ceramic)
1363
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:10μH(CDRH5D28C,SUMIDA)
CIN:4.7μF(ceramic)
CL:10μF(ceramic)
Step down ratio : 1.8V / 6.0V = 30%<PFM Duty 31%>
1364
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 (= 0.5Ω<TYP.>)
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)×85%*
* An assumed value of tolerance among the DCOUT voltage, the VROUT voltage, and the VD release voltage
(The VD detect voltage and hysteresis range).
1365
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.
<SOP-8 Recommended pattern layout>
1366
XC9510
Series
■TYPICAL PERFORMANCE CHARACTERISTICS
(A) DC/DC CONVERTER
(1) Efficiency vs. Output Current
1367
XC9510 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(2) Output Voltage vs. Output Current
1368
XC9510
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(3) Output Voltage vs. Ripple Voltage
1369
XC9510 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(4) Output Voltage vs. Ambient Temperature
(5) Soft Start Time vs. Ambient Temperature
1370
XC9510
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(6) DC/DC Supply Current vs. Ambient Temperature(VR:Shutdown)*
1371
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
1372
(9) U.V.L.O. Voltage vs. Ambient Temperature
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)
1373
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)
1374
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)
1375
XC9510 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR
(1) Output Voltage VS. Input Voltage
1376
XC9510
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(2) Output Voltage VS. Output Current (Current Limit)
1377
XC9510 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(3) Dropout Voltage VS. Output Current
1378
XC9510
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(4) Output Voltage VS. Output Current
1379
XC9510 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(5) Output Voltage VS. Ambient Temperature
1380
XC9510
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(6) Ripple Rejection Ratio VS. Ripple Frequency
1381
XC9510 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(7) VR LOAD TRANSIENT RESPONSE
1382
XC9510
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(C) VOLTAGE DETECTOR
(1) Output Current VS. Input Voltage
(2) Detect Voltage VS. Input Voltage
1383
XC9510 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(C) VOLTAGE DETECTOR (Continued)
(3) Detect Voltage,Release Voltage VS. Ambient Temperature
1384
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
1385
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
1386
SERIES
TYPE
XC9510
A
B
C
D
E
F
H
K
L
DC/DC CONTROL
METHODS
PWM Control
PWM, PFM/PWM
Manual Switch
CE=”VCEH” LEVEL
CE=”VCEM” LEVEL
-
-
DC/DC: ON
VR: OFF
VD: ON
DC/DC: ON
VR: ON
VD: ON
PFM / PWM Automatic
Switch
PWM Control
CE=”VCEL” LEVEL
VD SENSE PIN
DC/DC: OFF
VR: OFF
VD: ON
DC/DC: OFF
VR: OFF
VD: ON
DC/DC: OFF
VR: OFF
VD: ON
VDD
DCOUT
VROUT
VDD
DCOUT
VROUT
VDD
DCOUT
VROUT