October 28, 2003 Ver. 4
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! Input Voltage Range
! Output Voltage Range
! APPLICATIONS
" CD-R / RW, DVD
" HDD
" PDAs, portable communication modem
" Cellular phones
" Palmtop computers
" Cameras, video recorders
2.4V ~ 6.0V
! Switching Frequency
! Output Current
DC/DC
0.9 ~ 4.0V (±2%)
VR
0.9 ~ 4.0V (±2%)
VD
0.9 ~ 5.0V (±2%)
300kHz, 600kHz, 1.2MHz
! Ultra Small Packages
! Ceramic Capacitor Compatible
DC/DC
800mA
VR
600mA
SOP-8
! GENERAL DESCRIPTION
! FEATURES
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 steppeddown 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 and VR are set-up internally in
0.1V 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 builtin 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 APPLICATION CIRCUIT
Input Voltage Range :
2.4V ~ 6.0V
Load Capacitors :
Ceramic Capacitors Compatible
(Low ESR Capacitors)
VD Function :
Detects output voltage from the VDOUT pin
while sensing either VDD, DCOUT,
or VROUT internally.
Nch Open Drain Output
<DC/DC Converter>
Output Voltage Range : 0.9 ~ 4.0V (Accuracy ±2%)
Output Current :
800mA
Controls :
PWM Control
PWM, PWM / PFM Automatic
Switching External
Oscillation Frequency : 300kHz, 600kHz, 1.2MHz
<Regulator>
Output Voltage Range : 0.9 ~ 4.0V (Accuracy ±2%)
Current Limit
600mA
Dropout Voltage :
240mV @ IOUT=300mA (VOUT=2.8V)
High Ripple Rejection
60dB @1kHz (VOUT=2.8V)
! TYPICAL PERFORMANCE CHARACTERISTICS
XC9510Hxxxx
DC/DC Efficiency (DCOUT:3.4V, 1.2MHz), VR Efficiency (VROUT:3.0V)
VIN=5.0V, Topr=25 C, L:4.7uH(CDRH4D28C),
CIN:4.7uF(ceramic), CL1:10uF(ceramic), CL2:1uF(ceramic)
100
O
90
2
3
LX
PGND
CE/
DCOUT
MODE
8
VDD
6
VROUT
80
CL1
L
Efficiency EFFI (%)
1
( )
SD
DCOUT
7
VROUT
CL2
CIN
4
VDOUT
AGND
5
70
60
50
40
30
PWM/PFM switching control
20
PWM control
10
SOP-8 (Top View)
0
0.1
1
10
100
DC/DC Output Current IDOUT
VR Output Current IROUT (mA)
1000
Semiconductor Ltd.
Data Sheet
1
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! PIN ASSIGNMENT
! PIN CONFIGURATION
PIN
NUMBER
PGND 1
8 LX
CE/MODE 2
7 DCOUT
VDD 3
6 VROUT
VDOUT 4
5 AGND
SOP-8 (Top View)
PIN NAME
FUNCTION
1
PGND
Power Ground
2
CE/MODE
Chip Enable / MODE Switch
3
VDD
Power Supply
4
VDOUT
VD Output
5
AGND
Analog Ground
6
VROUT
VR Output
7
DCOUT
DC/DC Output
8
LX
Switch
! SELECTION GUIDE
" Ordering Information
XC9510
123456
DESIGNATOR
The input for the voltage regulator block comes from the DC/DC.
SYMBOL
1
23
DESCRIPTION
Control Methods and MODE pins, the VD Sense pin (See the chart below)
Setting voltage and specifications of each DC/DC, VR, and VD (Based on the internal standard)
Oscillation Frequency of DC/DC :
3
6
C
4
5
S
300kHz
600kHz
1.2MHz
Package Type :
SOP-8
Device Orientation :
6
R
L
Embossed Tape : Standard feed
Embossed Tape : Reverse feed
$ Control Methods, CE/MODE Pin, VDSENSE
SERIES
1
DC/DC CONTROL
METHODS
CE/MODE PINS
(H LEVEL)
CE/MODE PINS
(M LEVEL)
-
-
CE/MODE PINS
(L LEVEL)
A
VDD
B
C
DCOUT
VROUT
PWM Control
VDD
D
XC9510
VR : OFF
E
VR : ON
K
Stand-by Mode
(Except for VD)
DCOUT
VROUT
F
H
VD
SENSE
PWM, PFM/PWM
Manual Switch
PFM/PWM
Automatic Switch
VDD
PWM Control
DCOUT
VROUT
L
Semiconductor Ltd.
Data Sheet
2
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! PACKAGING INFORMATION
$ SOP-8
! BLOCK DIAGRAM
DCOUT
Phase
Compensation
+
Buffer,
Driver
logic
+
-
Vref with
soft start
LX
R amp Wave
Generator,
OSC
PGND
ON/OFF&
MODE
CONTROL
CE/MODE
Current Limit &
Feedback
PWM/PFM
Controller
eac h
circuit
VDD
VROUT
-
Current
Li mi t
U.V.L.O.
+
+
VDOUT
+
Vref
Vref
-
SENSE
(VDD or DCOUT or VROUT)
AGND
* Diodes shown in the above circuits are protective diodes.
! ABSOLUTE MAXIMUM RATINGS
Ta=25OC
PARAMETER
SYMBOL
RATINGS
UNITS
VDD Pin Voltage
AVDD
- 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
VDOUT Pin Voltage
VDOUT
- 0.3 ~ VDD + 0.3
V
LX Pin Voltage
LX
- 0.3 ~ VDD + 0.3
V
CE/MODE Pin Voltage
CE/MODE
Pd
- 0.3 ~ VDD + 0.3
V
mW
Topr
- 40 ~ + 85
O
C
- 55 ~ + 125
O
C
Continuous Power Dissipation (*1)
SOP-8
Operating Temperature Range
Storage Temperature Range
650
Tstg
(*1) IOUT = Pd / (VIN - VOUT) when PC board mounting.
(*2) Package power dissipation
Semiconductor Ltd.
Data Sheet
3
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! ELECTRICAL CHARACTERISTICS
XC9510HxxCSx
$ Common Characteristics
PARAMETER
Ta=25OC
SYMBOL
CONDITIONS
MIN.
TYP.
MAX.
UNITS
TEST CIRCUIT
Supply Current 1
IDD1
VIN=CE=DCOUT=5.0V
-
300
-
µΑ
Supply Current 2
IDD2
VIN=CE=5.0V, DCOUT=0V
-
240
-
µΑ
Stand-by Current (note 1)
ISTB
VIN=6.5V, CE=0V
-
0.6
2.5
µΑ
Input Voltage Range
VIN
2.4
-
6.0
V
U.V.L.O. Voltage (note 2)
VUVLO
1.00
1.40
1.78
V
CE 'H' Level Voltage
VCEH
0.6
-
VDD
V
CE 'M' Level Voltage
VCEM
-
-
VDD-1.2
V
1
1
1
3
3
3
3
1
1
CE 'L' Level Voltage
VCEL
VSS
-
0.25
V
CE 'H' Level Current
ICEH
- 0.1
-
0.1
µΑ
CE 'L' Level Current
ICEL
- 0.1
-
0.1
µΑ
$ DC/DC Converter (2.2V product)
Ta=25OC
PARAMETER
SYMBOL
Output Voltage
DCOUT
Oscillation Frequency
FOSC
Maximum Duty Ratio
MAXDUTY
Minimum Duty Ratio
MINDUTY
PFM Duty Ratio
PFMDUTY
LX SW 'High' On Resistance
(note 3)
RLXH
CONDITIONS
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
DCOUT=0V, LX=VIN-0.05V
MIN.
TYP.
MAX.
UNITS
TEST CIRCUIT
2.156
2.200
2.244
V
3
1.02
1.20
1.38
MHz
3
100
-
-
%
-
-
0
%
4
4
21
30
38
%
3
-
0.5
-
Ω
5
LX SW 'Low' On Resistance
RLXL
-
0.5
-
Ω
Maximum Output Current
IMAX1
800
-
-
mA
Current Limit
ILIM1
-
1.2
-
A
3
6
-
90
-
%
3
-
±100
-
ppm
/OC
3
-
5
-
mS
3
-
8
-
mS
3
Efficiency (note 4)
EFFI
Output Voltage
! VOUT
Temperature Characteristics
Soft Start Time
Latch Time (note 5)
Connected to the external components,
IDOUT=100mA
IDOUT=30mA
! Topr " VOUT -40OC<Topr<85OC
Connected to the external components,
TSS
CE=0V"VIN, IDOUT=1mA
Connected to the external components,
VIN=CE=5.0V,
Tlat
Short DCOUT by 1Ω resistor
$ Regulator (1.8V product)
Ta=25OC
PARAMETER
SYMBOL
CONDITIONS
MIN.
TYP.
MAX.
UNITS
TEST CIRCUIT
Output Voltage
VROUT(E)
IROUT=30mA
1.764
1.800
1.836
V
Maximum Output Current
IMAX2
200
-
-
mA
Load Regulation
! VROUT
1mA<IROUT<100mA
-
15
50
mV
Dropout Voltage 1 (note 6)
Vdif 1
IROUT=30mA
-
30
-
mV
-
85
-
mV
2
2
2
2
2
-
0.2
-
%/V
2
Dropout Voltage 2
Line Regulation
Vdif 2
IROUT=100mA
! VOUT
IROUT=30mA
! VIN " VOUT
VROUT(T)+1V<VIN<6V
Current Limit
ILIM2
VROUT=VROT(E)x0.9
-
600
-
mA
Short-Circuit Current
ISHORT
-
30
-
mA
7
7
Ripple Rejection Rate
PSRR
VROUT=VSS
VIN={VOUT(T) + 1.0} VDC + 0.5Vp-pAC
IROUT=30mA, f=1kHz
-
60
-
dB
2
-
±100
-
ppm
/OC
2
Output Voltage
Temperature Characteristics
! VOUT
IROUT=30mA
! Topr " VOUT -40OC<Topr<85OC
Semiconductor Ltd.
Data Sheet
4
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! ELECTRICAL CHARACTERISTICS (Continued)
$ Detector (2.7V product)
Ta=25OC
PARAMETER
SYMBOL
Detect Voltage
Hysteresis Range
MIN.
TYP.
MAX.
UNITS
TEST CIRCUIT
VDF
2.646
2.700
2.754
V
8
VHYS
3
5
8
%
-
1
-
-
mA
9
-
ppm
/OC
8
VD Output Current
IVD
Output Voltage
! VDF
Temperature Characteristics
! Topr " VDF
Test Conditions :
Unless otherwise stated;
CONDITIONS
VDOUT=0.5V
-40OC<Topr<85OC
-
±100
* VROUT(T) : Setting Output Voltage
DC/DC : VIN=3.6V [@ DCOUT:2.2V]
VD : VIN=6.0V
VR : VIN = VROUT(T) + 1.0 (V) [When VROUT(T) <1.4V, VIN =2.4V]
note 1 : VD operates when in stand-by mode.
note 2 : Including hysteresis operating voltage range.
note 3 : On resistance = 0.05V / ILX
note 4 : EFFI = { ( Output Voltage x Output Current ) / ( Input Voltage x Input Current) } x 100
note 5 : Time until it short-circuits DCOUT with GND through 1Ω of resistance from a state of operation
and is set to DCOUT=0V from current limit pulse generating.
note 6 : Vdif = (VIN1 (note 7) - VROUT1 (note 8 ) )
note 7 : VIN 1 = The input voltage when VROUT1 appears as input voltage is gradually decreased.
note 8 : VROUT1 = A voltage equal to 98% of the output voltage whenever an amply stabilized IOUT {VROUT(T) + 1.0V} is input.
Semiconductor Ltd.
Data Sheet
5
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! TEST CIRCUITS
Circuit 1
Supply Current, Stand-by Current,
Circuit
2
CE Current
1
A
A
LX
PGND
Output Voltage (VR), Load Stability, Dropout Voltage,
CE Current (MODE Current)
CE/MODE : VIN
or VIN-1.2V
or GND
8
PGND
LX
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
DCOUT : VIN or GND
1
V
V
IROUT
CIN : 4.7uF (ceramic)
CIN : 1.0uF (ceramic)
CL:1.0uF(ceramic,
2.2uF(ceramic,
3 Output Voltage (DC/DC) Oscillation Frequency,
Circuit
Circuit
4
VROUT>1.5V)
VROUT<1.5V)
Minimum Duty Cycle, Maximum Duty Cycle
U.V.L.O. Voltage, Softstart Time, Latch Time, CE Voltage,
(PFM Duty Cycle), (MODE Voltage)
L
1
PGND
LX
8
2
CE/
MODE
DCOUT
7
3
VDD
VROUT
6
4
VDOUT
AGND
5
LX
8
2
CE/
MODE
PGND
DCOUT
7
3
VDD
VROUT
6
4
VDOUT
AGND
5
1
CE : VIN
V
V
IDOUT
200Ω
V
CL : 10uF
(ceramic)
CIN : 4.7uF (ceramic)
FOSC
300kHz
600kHz
1.2MHz
Circuit
5
L
22uH
10uH
4.7uH
CIN : 1.0uF(ceramic)
Lx ON Resistance
Circuit
6
Current Limit 1 (DC/DC)
L
PGND
1
CE : VIN
LX
8
A
1
PGND
LX
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
CE : VIN
IDOUT
V
CIN : 4.7uF (ceramic)
CIN : 1.0uF (ceramic)
Circuit
7
Current Limit 2 (VR), Short Protection (VR)
PGND
1
CE : VIN
LX
8
2
CE/
MODE
DCOUT
7
3
VDD
VROUT
6
4
VDOUT
AGND
5
Circuit
8
Detect Voltage, Release Voltage
1
VD_SENSE
(DCOUT or VROUT)
CE/MODE : VSS
A
V
PGND
LX
8
2
CE/
MODE
DCOUT
7
3
VDD
VROUT
6
4
VDOUT
AGND
5
200k Ω
V
V
CIN:
1uF
CIN : 4.7uF (ceramic)
Circuit
9
CL : 1.0uF (ceramic)
VD Output Current
VD_SENSE
(DCOUT or VROUT)
A
V
LX
8
2
CE/
MODE
DCOUT
7
3
VDD
VROUT
6
4
VDOUT
AGND
5
1
CE : VSS
PGND
CIN :
1uF
Semiconductor Ltd.
Data Sheet
6
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! TYPICAL APPLICATION CIRCUIT
1
2
3
LX
PGND
CE/
DCOUT
MODE
VDD
VROUT
( )
SD
CL1
L
DCOUT
8
7
VROUT
6
FOSC
L
1.2MHz
4.7µH (CDRH4D28C, SUMIDA)
600kHz
10µH (CDRH4D28C, SUMIDA)
300kHz
22µH (CDRH4D28C, SUMIDA)
CL2
CIN
4
VDOUT
AGND
5
SOP-8
(TOP VIEW)
CIN
: 4.7µF (ceramic, TAIYO-YUDEN)
CL1
: 10µF (ceramic, TAIYO-YUDEN)
CL2
:
1µF (ceramic, TAIYO-YUDEN), VROUT>1.5V
: 2.2µF (ceramic, TAIYO-YUDEN), VROUT<1.5V
! 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.
< 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 mode 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 can not
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.
Semiconductor Ltd.
Data Sheet
7
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! OPERATIONAL EXPLANATION (Continued)
< Synchronous / Non-synchronous >
The XC9510 series automatically switches synchronous / non synchronous according to the state of the DC/DC converter.
In the series, highly efficient operation using the synchronous mode while the coil current is in a continuation state.
The series enters non-synchronous operation when the built-in Nch switching transistor for synchronous operaion is shutdown which happens
when the load current becomes low and the operation changes to a disconsinuous state.
The IC can operate without an external schottky diode because the parasitic diode in the Nch switching transistor provides the circuit's stepdown operation. However, since Vf of the parasitic diode is 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
ILmax
Coil Current
ILmax
ILmin
Coil Current
0mA
0mA
LX
W ave Form
LX
W ave Form
< 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 1.2A.
Limit<8mS
*
Limit>8mS
*
Current Limit LEVEL
IDOUT
0mA
DCOUT
VSS
LX
CE
Restart
VIN
*1.2MHz, Typical
Semiconductor Ltd.
Data Sheet
8
XC9510 Series
Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator In Series plus Voltage Detector
Preliminary
! 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 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 Pch 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.
$ 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 0.6 µA (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 0 µA (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.
Semiconductor Ltd.
Data Sheet
9