XC9511 Series
ETR1008_001
Synchronous Step-Down DC/DC Converter
with Built-In LDO Regulator In Parallel Plus Voltage Detector
■GENERAL DESCRIPTION
The XC9511 series consists of a step-down DC/DC converter and a high-speed LDO regulator connected in parallel with the
DC/DC converter's output. A voltage detector is also built-in. Since the input for the LDO voltage regulator block comes
from the input power supply, it is suited for use with various applications.
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 XC9511 can deliver output currents up to 800mA at efficiencies over 90%.
The XC9511 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
and VR are set-up internally in 100mV steps 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.
■APPLICATIONS
●CD-R / RW, DVD
●HDD
●PDAs, portable communication modem
●Palmtop computers
●Cellular phones
●Cameras, video recorders
■FEATURES
DC/DC Converter with Built-in LDO and VD Function
Input Voltage Range : 2.4V ~ 6.0V
Low ESR Capacitor : Ceramic capacitor compatible
VD Function
: Three VD sensing Options for either
VDD, DCOUT, or VROUT
Package
: SOP-8
<DC/DC Converter Block>
Output Voltage Range : 0.9V ~ 4.0V (Accuracy ± 2%)
Output Current
: 800mA
Control Method
: PWM or PWM/PFM Selectable
Oscillation Frequency : 300kHz, 600kHz, 1.2MHz
<Regulator Block>
Regulator Input
: Parallel Input to DC/DC converter
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 APPLICATION CIRCUIT
■TYPICAL PERFORMANCE
CHARACTERISTICS
XC9511Axxx
VIN=5.0V, Topr=25oC, L: 4.7μH(CDRH4D28C)
CIN: 4.7μF(ceramic), CL1: 10μF(ceramic), CL2: 4.7μF(ceramic)
SOP-8 (TOP VIEW)
* Please refer to the typical application circuit when
external components are selected.
1/35
XC9511 Series
■PIN CONFIGURATION
PGND 1
8 LX
PVDD 2
7 DCOUT
AVDD 3
6 VROUT
VDOUT 4
5 AGND
SOP-8 (TOP VIEW)
■PIN ASSIGNMENT
PIN NUMBER
PIN NAME
FUNCTION
1
2
3
4
5
6
7
8
PGND
PVDD
AVDD
VDOUT
AGND
VROUT
DCOUT
LX
Power Ground
Power Supply 1
Power Supply 2
VD Output
Analog Ground
VR Output
DC/DC Output
Switch
■PRODUCT CLASSIFICATION
●Ordering Information
XC9511①②③④⑤⑥
DESIGNATOR
①
② ③
The input for the voltage regulator block comes from VDD
DESCRIPTION
SYMBOL
Control Methods and
the VD Sense Pin
Setting Voltage &
Specifications
As chart
below
Internal
standard
3
6
C
S
R
L
④
DC/DC Oscillation Frequency
⑤
Package
⑥
Device Orientation
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 and VD SENSE Pin
SERIES
XC9511
2/35
①
A
B
C
D
E
F
DC/DC CONTROL METHODS
PWM control
PFM/PWM Automatic Switch
VD SENSE
VDD
DCOUT
VROUT
VDD
DCOUT
VROUT
XC9511
Series
■BLOCK DIAGRAM
* Diodes shown in the above circuit are protective diodes
■ABSOLUTE MAXIMUM RATINGS
Ta = 25℃
PARAMETER
SYMBOL
RATINGS
UNIT
AVDD Pin Voltage
PVDD Pin Voltage
DCOUT Pin Voltage
VROUT Pin Voltage
VROUT Pin Current
VDOUT Pin Voltage
VDOUT Pin Current
Lx Pin Voltage
Lx Pin Current
Power Dissipation
SOP-8
Operating Temperature Range
Storage Temperature Range
AVDD
PVDD
DCOUT
VROUT
IROUT
VDOUT
IVD
Lx
ILx
Pd
Topr
Tstg
- 0.3 ~ 6.5
AVDD - 0.3 ~ AVDD + 0.3
- 0.3 ~ AVDD + 0.3
- 0.3 ~ AVDD + 0.3
800
- 0.3 ~ VDD + 0.3
50
- 0.3 ~ VDD + 0.3
±1300
650
- 40 ~ + 85
- 55 ~ + 125
V
V
V
V
mA
V
mA
V
mA
mW
℃
℃
(*) When implemented on a glass epoxy PCB.
3/35
XC9511 Series
■ELECTRICAL CHARACTERISTICS
XC9511xxxCSx
●Common Characteristics
Topr=25℃
PARAMETER
SYMBOL
Supply Current 1
IDD1
Supply Current 2
IDD2
Input Voltage Range
VIN
CONDITIONS
MIN.
TYP.
MAX.
UNITS
VIN=CE=DCOUT=5.0V
-
250
310
μA
1
VIN=CE=5.0V, DCOUT=0V
-
300
360
μA
1
2.4
-
6.0
V
-
●DC/DC Converter (1.5V product)
PARAMETER
CIRCUIT
Topr=25℃
SYMBOL
CONDITIONS
Connected to the external components
MIN.
TYP.
MAX.
UNITS
CIRCUIT
1.470
1.500
1.530
V
3
1.02
1.20
1.38
MHz
3
Output Voltage
DCOUT(E)
Oscillation Frequency
FOSC
Maximum Duty Ratio
MAXDUTY
DCOUT=0V
100
-
-
%
4
Minimum Duty Ratio
MINDUTY
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
PFM Duty Ratio
* XC9511D/E/F
PFMDUTY
U.V.L.O. Voltage (*1)
VUVLO
LX SW ‘High’ ON Resistance (*2)
RLXH
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,
LX SW ‘Low’ ON Resistance
RLXL
LX SW ‘High’ Leak Current (*11)
IleakH
VIN=LX=6.0V, CE=0V
-
0.05
1.00
μA
11
LX SW ‘Low’ Leak Current (*11)
IleakL
VIN=6.0V, LX=CE=0V
-
0.05
1.00
μA
11
Maximum Output Current
Imax1
Connected to the external components
800
-
-
mA
3
Current Limit (*8)
Ilim1
1.0
1.1
-
A
6
-
90
-
%
3
-
±100
-
2
5
10
ms
3
-
8
25
ms
10
Efficiency (*3)
Output Voltage
Temperature Characteristics
4/35
EFFI
VIN=5.0V
Connected to the external components
IDOUT=100mA
U DCOUT
IDOUT=30mA
△Topr・DCOUT -40℃≦Topr≦85℃
Soft-Start Time
TSS
Latch Time (*4, 9)
Tlat
Connected to the external components,
CE=0VtVIN, IDOUT=1mA
Connected to the external components,
VIN=CE=5.0V, Short DCOUT by 1Ωresistor
ppm/
℃
3
XC9511
Series
■ELECTRICAL CHARACTERISTICS (Continued)
XC9511xxxCSx (Continued)
●Regulator (3.3V product)
Topr=25℃
PARAMETER
SYMBOL
CONDITIONS
MIN.
TYP.
MAX.
3.234
3.300
400
-
1mA≦IROUT≦100mA
-
IROUT=30mA
UNITS
CIRCUIT
3.366
V
2
-
mA
2
15
50
mV
2
Output Voltage
VROUT(E)
Maximum Output Current
Imax2
Load Regulation
U VROUT
Dropout Voltage 1 (*5)
Vdif 1
IROUT=100mA
-
50
110
mV
2
Dropout Voltage 2
Vdif 2
IROUT=200mA
-
100
200
mV
2
Line Regulation
UVROUT
UVIN・VROUT
IROUT=30mA
-
0.05
0.25
%/V
2
480
600
-
mA
7
-
30
-
mA
7
-
60
-
dB
12
-
±100
-
VROUT(T)+1V≦VIN≦6V
Current Limit
Ilim2
VROUT=VROUT(E) x 0.9
Short-Circuit Current
Ishort
VROUT=VSS
Ripple Rejection Rate
PSRR
Output Voltage
UVROUT
UTopr・VROUT
Temperature Characteristics
VIN={VOUT(T)+1.0} VDC+0.5Vp-pAC,
IROUT=30mA, f=1kHz
IROUT=30mA
-40℃≦Topr≦85℃
ppm/
●Detector (2.7V product)
Topr=25℃
PARAMETER
SYMBOL
Detect Voltage
VDF(E)
Hysteresis Range
VHYS
VD Output Current
IVD
Output Voltage
UVDF
UTopr・VDF
Temperature Characteristics
2
℃
CONDITIONS
MIN.
TYP.
MAX.
UNITS
CIRCUIT
2.646
2.700
2.754
V
8
VHYS=[VDR(E) (*10) - VDF(E)] / VDF(E) x 100
2
5
8
%
8
VDOUT=0.5V, CE=0V
1
-
-
mA
9
CE=0V
-40℃≦Topr≦85℃
-
±100
-
ppm/
℃
8
Test conditions: Unless otherwise stated:
DC/DC : VIN=3.6V [DCOUT:1.5V]
VR: VIN = 4.3V (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 hysteresis operating voltage range.
*2:
ON resistance (Ω)= 0.05 (V) / ILX (A).
*3:
EFFI = { ( Output Voltage x Output Current ) / ( Input Voltage x Input Current) } x 100
*4: 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.
*5:
Vdif = (VIN1 (*6) - VROUT1 (*7))
*6:
VIN 1 = The input voltage when VROUT1 appears as input voltage is gradually decreased.
*7:
VROUT1 = A voltage equal to 98% of the output voltage whenever an amply stabilized IOUT {VROUT(T) + 1.0V} is input.
*8:
Current limit = When VIN is low, limit current may not be reached because of voltage falls caused by ON resistance or serial
*9:
Integral latch circuit=latch time may become longer and latch operation may not work when VIN is 3.0V or more.
resistance of coils.
*10:
VDR(E) = VD release voltage
*11: When temperature is high, a current of approximately 5.0μA (maximum) may leak.
*12: When using the IC with a regulator output at almost no load, a capacitor should be placed as close as possible between
AVDD and AGND (CIN2), connected with low impedance. Please also see the recommended pattern layout on page 13
for your reference. Should it not be possible to place the input capacitor nearby, the regulated output level may increase
up to the VDD level while the load of the DC/DC converter increases and the regulator output is at almost no load.
5/35
XC9511 Series
■TEST CIRCUITS
Circuit 1
Supply Current
Circuit 2
Output Voltage (VR), Load Regulation, Dropout Voltage,
Maximum Output Current
Circuit 3
Output Voltage (DC/DC) Oscillation Frequency,
U.V.L.O. Voltage, Soft start Time
Maximum Output Current, Efficiency,
(PFM Duty Cycle),
Circuit 4
Minimum Duty Cycle, Maximum Duty Cycle
Circuit 5
Lx ON Resistance
Circuit 6
Current Limit 1 (DC/DC)
6/35
XC9511
Series
■TEST CIRCUITS (Continued)
Circuit 7
Current Limit 2 (VR), Short Current (VR)
Circuit 8
Detect Voltage, Release Voltage (Hysteresis Range)
* For the measurement of the VDD_Sense products,
the input voltage was controlled.
Circuit 9
VD Output Current
Circuit 10
Latch Time
Circuit 12
Ripple Rejection Rate
* For the measurement of the VDD_Sense products,
the input voltage was controlled.
Circuit 11
Off-Leak
7/35
XC9511 Series
■TYPICAL APPLICATION CIRCUIT
FOSC
1.2MHz
600KHz
300kHz
L
4.7μH
(CDRH4D28C, SUMIDA)
10μH
(CDRH5D28, SUMIDA)
22μH
(CDRH6D28, SUMIDA)
SOP-8 (TOP VIEW)
CIN
CL1
4.7μF
(ceramic, TAIYO YUDEN)
10μF
(ceramic, TAIYO YUDEN)
2
CL2 *
IROUT＜300mA
IROUT≧300mA
4.7μF (ceramic, TAIYO YUDEN)
10μF (ceramic, TAIYO YUDEN)
SD *1: XB0ASB03A1BR (TOREX)
*1 The DC/DC converter of the XC9511 series automatically switches between synchronous / non-synchronous. The Schottky
diode is not normally needed. However, in cases where high efficiency is required when using the DC/DC converter during light
load while in non-synchronous operation, please connect a Schottky diode externally.
*2 Please pay much attention when external components are selected as recommended value of CL2 will be changed by the load
current.
■OPERATIONAL EXPLANATION
The XC9511 series consists of a synchronous step-down DC/DC converter, a high speed LDO voltage regulator, and a
voltage detector.
●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.
<PWM/PFM>
The XC9511A to C series are PWM control, while the XC9511D to F series can be automatically switched to PWM/PFM
control. The PWM mode of the XC9511A to C series are controlled on a specified frequency from light loads through to
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 XC9511D to F series can switch to PWM/PFM automatic
switching control. 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. The series cannot control only PFM mode. 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.
8/35
XC9511
Series
■OPERATIONAL EXPLANATION (Continued)
<Synchronous / Non-synchronous>
The XC9511 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
<Current Limit>
The current limiter circuit of the XC9511 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.
①When 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.
②When the driver transistor is turned off, the limiter circuit is then released from the current limit detection state.
③At the next pulse, the driver transistor is turned on. However, the transistor is immediately turned off in the case of an
over current state.
④When 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 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 XC9511 series can be set at 1.1A.
9/35
XC9511 Series
■OPERATIONAL EXPLANATION (Continued)
<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 XC9511 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 VOUT, and the amplifier controls the output of the
Pch driver transistor.
<Current Limit Circuit>
The voltage regulator block includes a combination of a constant current limiter circuit and a foldback circuit. The
voltage regulator senses output current of the built-in P channel output driver transistor inside. 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.
●Voltage Detector
The detector block of the XC9511 series detects output voltage from the VDOUT pin while sensing either VDD, DCOUT, or
.
VROUT internally. (N channel Open Drain Type)
10/35
XC9511
Series
■NOTES ON USE
●Application Information
1.
The XC9511 series is designed for use with a ceramic output capacitor. 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. Once the design has been completed, verification with actual components should be done.
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)
5.
< External Components>
L:4.7μH(CDRH4D28C,SUMIDA)
CIN:4.7μF(ceramic)
CL:10μF(ceramic)
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
11/35
XC9511 Series
■NOTES ON USE (Continued)
●Application Information (Continued)
6. When the XC9511D to F series operate 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).
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 use XC9511A to C types (PWM control) 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(CDRH5D28,SUMIDA)
CIN:4.7μF(ceramic)
CL:10μF(ceramic)
Step-down ratio: 1.8V / 6.0V = 30% <PFM Duty 31%>
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. When using IC with a regulator output at almost no load, a capacitor should be placed as close as possible between
AVDD and AGND (CIN2), connected with low impedance. Please also see the recommended pattern layout for your
reference. Should it not be possible to place the input capacitor nearby, the regulated output level may increase up
to the VDD level while the load of the DC/DC converter increases and the regulator output is at almost no load.
12/35
XC9511
Series
■NOTES ON USE (Continued)
●Application Information (Continued)
14.
Should the bi-directional load current of the synchronous DC/DC converter and the regulator become large, please
be careful of the power dissipation when in use. Please calculate power dissipation by using the following formula.
Pd=PdDC/DC + PdVR
2
DC/DC power dissipation (when in synchronous operation): PdDC/DC = IDOUT x RON
VR power dissipation: PdVR=(VIN – VROUT) x IROUT
RON: ON resistance of the built-in driver transistor to the DC/DC (= 0.5Ω<TYP.>)
RON=Rpon x PchOnDuty / 100
+ Rnon x (1 - PchOnDuty / 100)
15.
The voltage detector circuit built-in the XC9511 series internally monitor the VDD pin voltage, the DC/DC output pin
voltage and VR output pin voltage. For the XC9511B/C/E/F 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).
●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 AVDD & AGND pins. Should it not be possible to place the input capacitors nearby, the regulated
output level may increase because of the switching noise of the DC/DC converter.
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.
caused by the noise may occur depending on the arrangement of the Schottky diode.
6.
Please use the AVDD and PVDD pins with the same electric potential.
Characteristic degradation
<SOP-8 Reference pattern layout>
13/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS
(A) DC/DC CONVERTER
(1) Efficiency vs. Output Current
14/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(2) Output Voltage vs. Output Current
15/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(3) Output Voltage vs. Ripple Voltage
16/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(4) Output Voltage vs. Ambient Temperature
(5) Soft-Start Time vs. Ambient Temperature
17/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(6) LX Pch/Nch On Resistance vs. Input Voltage
(7) Oscillation Frequency vs. Ambient Temperature
Ambient Temperature :Ta(℃)
18/35
(8) U.V.L.O. Voltage vs. Ambient Temperature
Ambient Temperature :Ta(℃)
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(9-1) DC/DC Load Transient Response (DCOUT: 1.5V, FOSC: 1.2MHz)
(a) PWM Control* (*XC9511A/B/C series)
(b) PWM/PFM Automatic Switching Control* (*XC9511D/E/F series)
19/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(9-2) DC/DC Load Transient Response (DCOUT: 1.8V, FOSC: 1.2MHz)
(a) PWM Control* (*XC9511A/B/C series)
(b) PWM/PFM Automatic Switching Control* (*XC9511D/E/F series)
20/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(9-3) DC/DC Load Transient Response (DCOUT: 3.3V, FOSC: 600kHz)
(a) PWM Control* (*XC9511A/B/C series)
(b) PWM/PFM Automatic Switching Control* (*XC9511D/E/F series)
21/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(9-4) DC/DC Load Transient Response (DCOUT: 1.5V, FOSC: 600kHz)
(a) PWM Control* (*XC9511A/B/C series)
(b) PWM/PFM Automatic Switching Control* (*XC9511D/E/F series)
22/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(9-5) DC/DC Load Transient Response (DCOUT: 1.8V, FOSC: 600kHz)
(a) PWM Control* (*XC9511A/B/C series)
(b) PWM/PFM Automatic Switching Control* (*XC9511D/E/F series)
23/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(A) DC/DC CONVERTER (Continued)
(9-6) DC/DC Load Transient Response (DCOUT: 3.3V, FOSC: 600kHz)
(a) PWM Control* (*XC9511A/B/C series)
(b) PWM/PFM Automatic Switching Control* (*XC9511D/E/F series)
24/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR
(1) Output Voltage vs. Input Voltage
25/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(2) Output Voltage vs. Output Current (Current Limit)
26/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(3) Dropout Voltage vs. Output Current
Ta=-40℃
27/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(4) Output Voltage vs. Output Current
28/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(5) Ripple Rejection Ratio vs. Ripple Frequency
29/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(B) VOLTAGE REGULATOR (Continued)
(6) VR Load Transient Response
30/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(C) VOLTAGE DETECTOR
(1) Output Current vs. Input Voltage
(2) Detect Voltage vs. Input Voltage
31/35
XC9511 Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(C) VOLTAGE DETECTOR (Continued)
(3) Detect Voltage, Release Voltage vs. Ambient Temperature
32/35
XC9511
Series
■TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
(D) COMMON
(1) Supply Current vs. Ambient Temperature (DC/DC & VR & VD)
33/35
XC9511 Series
■PACKAGING INFORMATION
●SOP-8
■MARKING RULE
●SOP-8
①②Represents product series
MARK
①
1
PRODUCT SERIES
②
1
XC9511xxxxSx
③Represents DC/DC control methods, MODE pin and VD sense pin
MARK
DC/DC CONTROL
A
SOP-8 (TOP VIEW)
B
C
D
E
F
PWM Control
PWM,
PFM/PWM Manual Switch
VD SENSE
PRODUCT SERIES
VDD
XC9511AxxxSx
XC9511BxxxSx
XC9511CxxxSx
XC9511DxxxSx
XC9511ExxxSx
XC9511FxxxSx
DCOUT
VROUT
VDD
DCOUT
VROUT
④⑤Represents detect voltage DC/DC,VR and VD (ex.)
MARK
④
1
⑤
4
DC/DC
VR
VD
PRODUCT SERIES
1.8V
3.3V
4.0V
XC9511*14*S*
⑥Represents oscillation frequency
MARK
3
6
C
OSCILLATION FREQUENCY
300kHz
600kHz
1.2MHz
PRODUCT SERIES
XC9511xxx3Ax
XC9511xxx6Ax
XC9511xxxCAx
⑦Represents single digit of production year (ex.)
MARK
3
4
PRODUCTION YEAR
2003
2004
⑧⑨Represents the 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.
34/35
XC9511
Series
1. The products and product specifications contained herein are subject to change without
notice to improve performance characteristics.
Consult us, or our representatives
before use, to confirm that the information in this catalog is up to date.
2. We assume no responsibility for any infringement of patents, patent rights, or other
rights arising from the use of any information and circuitry in this catalog.
3. Please ensure suitable shipping controls (including fail-safe designs and aging
protection) are in force for equipment employing products listed in this catalog.
4. The products in this catalog are not developed, designed, or approved for use with such
equipment whose failure of malfunction can be reasonably expected to directly
endanger the life of, or cause significant injury to, the user.
(e.g. Atomic energy; aerospace; transport; combustion and associated safety
equipment thereof.)
5. Please use the products listed in this catalog within the specified ranges.
Should you wish to use the products under conditions exceeding the specifications,
please consult us or our representatives.
6. We assume no responsibility for damage or loss due to abnormal use.
7. All rights reserved. No part of this catalog may be copied or reproduced without the
prior permission of Torex Semiconductor Ltd.
35/35