TOREX XC9509 User Manual

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XC9509 Series

ETR1006_001

Synchronous Step-Down DC/DC Converter
with Built-In LDO Regulator in Parallel Plus Voltage Detector

GENERAL DESCRIPTION

The XC9509 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 XC9509 can deliver output currents up to 600mA at efficiencies over 90%.
The XC9509 is designed for use with small ceramic capacitors.
A choice of three switching frequencies are available, 300kHz, 600kHz, and 1.2MHz. 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. 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
either the DC/DC block or the regulator block.

PPLICATIONS

●CD-R / RW, DVD

●HDD

●PDAs, portable communication modem

●Cellular phones

●Palmtop computers

●Cameras, video recorders

TYPICAL APPLICATION CIRCUIT

MSOP-10 (TOP VIEW)

* Please refer to the typical application circuit when

external com

onents are selected.

FEATURES

Input Voltage Range : 2.4V ~ 6.0V
Low ESR Capacitor : Ceramic capacitor compatible
VD Function : Sense internally either V

or V

Small Package : MSOP-10, USP-10

<DC/DC Converter Block>
Output Voltage Range : 0.9V ~ 4.0V (Accuracy±2%)
Output Current : 600mA (for MSOP-10 package)

400mA (for USP-10 package)

Control Method : PWM or PWM/PFM Selectable
Oscillation Frequency : 300kHz, 600kHz, 1.2MHz

<Regulator Block>
Reglator Output : Parallel Input to DC/DC Converter
Output Voltage Range : 0.9V ~ 4.0V (Accuracy±2%)
Current Limit : 300mA
Dropout Voltage : 80mV @ I
High Ripple Rejection : 60dB @1kHz (V

ROUT. N-ch open drain output

OUT=100mA (VOUT=2.8V)

OUT=2.8V)

DD, DCOUT,

■TYPICAL PERFORMANCE

CHARACTERISTICS

C9509Hxxxx

CIN:4.7μF (ceramic), CL1:10μF (ceramic), CL2: 4.7μF (ceramic)

VIN=3.6V, Topr=25℃, L=4.7μH (CDRH4D28C),

1/41

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XC9509 Series

PIN CONFIGURATION

●Control Methods, MODE Pins, VD SENSE Pins

* The XC9509A to F series' MODE pin switches either the regulator block or DC/DC block to stand-by mode.

*The dissipation pad for the USP-10 package

should be solder-plated in recommended
mount pattern and metal masking so as to
enhance mounting strength and heat release.
If the pad needs to be connected to other pins,
it should be connected to the AGND pin.

PRODUCT CLASSIFICATION

●Ordering Information

XC9509①②③④⑤⑥ : The input for the voltage regulator block comes from VDD.

DESIGNATOR DESCRIPTION SYMBOL DESCRIPTION

①

②③

④

⑤

⑥

SERIES ① DC/DC CONTROL METHODS

XC9509

When the CE mode is off, every function except for the VD function enters into the stand-by mode.
(The MODE pin does not operate independently.)

MSOP-10 (TOP VIEW)

USP-10 (BOTTOM VIEW)

Control Methods, the
MODE Pin, & the VD

Sense Pin

Setting Voltage &

Specifications

DC/DC Oscillation

Frequency

Package &

DC/DC Current Limit

Device Orientation

A VDD

B DCOUT

C

D VDD

E DCOUT

F

H VDD

K DCOUT

L

PWM Control

PWM, PFM/PWM Manual

Switch

As chart below : -

Internal

standard

3 : 300kHz

6 : 600kHz
C : 1.2MHz
A : MSOP-10, Current limiter: 1.1A (TYP.)
D : USP-10, Current limiter: 0.7A (TYP.)
R : Embossed Tape, standard feed

L : Embossed Tape, reverse feed

PIN ASSIGNMENT

PIN NUMBER PIN NAME FUNCTION

1 PGND Power Ground
2 CE Chip Enable
3 PVDD Power Supply 1
4 AVDD Power Supply 2
5 VDOUT VD Input
6 AGND Analog Ground
7 MODE Mode Switch
8 VROUT VR Output

9 DCOUT DC/DC Output Sense

10 LX Switch

: Setting voltage and specifications of each DC/DC, VR,
and VD (Based on the internal standard)

MODE PINS

(H LEVEL)

VR: OFF VR: ON

DC/DC: OFF DC/DC: ON

PFM/PWM Auto

Switch

MODE PINS

(L LEVEL)

PWM Control

VD SENSE

VROUT

VROUT

ROUT

V

2/41

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A

BLOCK DIAGRAM

BSOLUTE MAXIMUM RATINGS

DCOUT

CE

AVDD

VDOUT

PAR AMETER SYMBOL RATINGS UNIT

AVDD Pin Voltage AVDD - 0.3 ~ 6.5 V

PVDD Pin Voltage PVDD AVDD - 0.3 ~ AVDD + 0.3 V
DCOUT Pin Voltage DCOUT - 0.3 ~ AVDD + 0.3 V
VROUT Pin Voltage VROUT - 0.3 ~ AVDD + 0.3 V
VROUT Pin Current IROUT 800 mA
VDOUT Pin Voltage VDOUT - 0.3 ~ AVDD + 0.3 V
VDOUT Pin Current IVD 50 mA

Lx Pin Voltage Lx - 0.3 ~ AVDD + 0.3 V

Lx Pin Current

CE Pin Voltage CE - 0.3 ~ AVDD + 0.3 V

MODE Pin Voltage MODE - 0.3 ~ AVDD + 0.3 V

Power Dissipation

Operating Temperature Range Topr - 40 ~ + 85 ℃

Storage Temperature Range Tstg - 55 ~ + 125 ℃

(*) When PC board mounted.

Phase

Compensation

ON/OFF

Control

U.V .L.O

Vref with
soft start

each circuit

-

+

+

-

-

+

PWM/ PFM

Controller

Vref

+

SENSE
(V DD or DCOUT or VRO UT)

-

Limit & Feedback

Ramp Wave

Generator,

logic

Current

OSC

each circuit

Current

Limit

Buffer,

Driv er

MODE

Control

+

-

Vref

* Diodes shown in the above circuit are protective diodes.

Ta = 2 5 ℃

MSOP-10 1300

USP-10

MSOP-10 350 (*)

USP-10

ILx

Pd

900

150

mA

mW

XC9509

Series

PVDD

LX

PGND

MODE

VROUT

AGND

3/41

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XC9509 Series

ELECTRICAL CHARACTERISTICS

XC9509xxxCAx

●Common Characteristics

PARAMETER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS

Supply Current 1 IDD1 VIN=CE=DCOUT=5.0V - 250 310

Supply Current 2 IDD2 VIN=CE=5.0V, DCOUT=0V - 300 360

Stand-by Current (*1) ISTB VIN=6.5V, CE=0V - 3.0 7.0

Input Voltage Range VIN 2.4 - 6.0 V -

CE ‘H’ Level Voltage VCEH 0.6 - VDD V 3

CE ‘L’ Level Voltage VCEL VSS - 0.25 V 3

CE ‘H’ Level Current ICEH - 0.1 - 0.1

CE ‘L’ Level Current ICEL - 0.1 - 0.1

MODE 'H' Level Voltage

*XC9509A/B/C

MODE 'H' Level Voltage

*XC9509D/E/F/H/K/L

MODE 'L' Level Voltage

*XC9509A/B/C

MODE 'L' Level Voltage

*XC9509D/E/F/H/K/L

V

MH

V

MH

V

ML

V

ML

0.6 - VDD V 2

0.6 - VDD V 3

VSS - 0.25 V 2

VSS - 0.25 V 3

MODE 'H' Level Current IMH - 0.1 - 0.1

MODE 'L' Level Current IML - 0.1 - 0.1

●DC/DC Converter (1.5V product)

PARAMETER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS

Supply Current 1 *XC9509A/B/C IDD_DC1 VIN=CE=DCOUT=5.0V - 200 280

Supply Current 2 *XC9509A/B/C IDD_DC2 VIN=CE=5.0V, DCOUT=0V 250 330

PFM Supply Current 1 *

XC9509H/K/L

PFM Supply Current 2

* XC9509H/K/L

Output Voltage DCOUT(E)

Oscillation Frequency FOSC

I

DD_PFM1 VIN=CE=DCOUT=5.0V 250 310

I

DD_PFM2 VIN=CE=5.0V, DCOUT=0V 300 360

Connected to the external components,

I

DOUT

=30mA

Connected to the external components,

I

DOUT

=10mA

1.470 1.500 1.530 V 3

1.02 1.20 1.38 MHz 3

Maximum Duty Ratio MAXDUTY DCOUT=0V 100 - - % 4

Minimum Duty Ratio MINDUTY DCOUT=VIN - - 0 % 4

PFM Duty Ratio

*XC9509H/K/L

PFMDUTY

U.V.L.O. Voltage (*2) VUVLO

Connected to the external components,

No load

Connected to the external components

21 30 38 % 3

1.00 1.40 1.78 V 3

LX SW ‘High’ ON Resistance (*3) RLXH DCOUT=0V, LX=VIN-0.05V - 0.5 1.0 Ω 5

LX SW ‘Low’ ON Resistance RLXL

Connected to the external components,

V

IN

=5.0V

- 0.5 0.9

LX SW ‘High’ Leak Current (*12) IleakH VIN=LX=6.0V, CE=0V - 0.05 1.00

LX SW ‘Low’ Leak Current (*12) IleakL VIN=6.0V, LX=CE=0V - 0.05 1.00

Maximum Output Current Imax1

Connected to the external components

600 - - mA 3

Current Limit (*9) Ilim1 1.0 1.1 - A 6

Efficiency (*4) EFFI

Output Voltage

Temperature Characteristics

Soft-Start Time TSS

Latch Time (*5, 10) Tlat

U DCOUT

(UTopr・D

Connected to the external components,

I

DOUT

=100mA

DOUT=30mA

I

-40℃<

COUT

)

Topr<85℃

Connected to the external components,

CE=0VV

IN

, I

DOUT

=1mA

Connected to the external components,

VIN=CE=5.0V, Short D

COUT

by 1Ω resistor

- 90 - % 3

- +

100 -

2 5 10 ms 3

- 8 25 ms 10

μA
μA
μA

μA
μA

μA
μA

μA
μA

μA

μA

Ω

μA
μA

ppm/

℃

Topr=25℃

CIRCUIT

1

1

1

1

1

1

1

Topr=25℃

CIRCUIT

1

1

1

1

3

11

11

3

4/41

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XC9509

Series

ELECTRICAL CHARACTERISTICS (Continued)

XC9509xxxCAx (Continued)

●Regulator (3.3V product)

PARAMETER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS

Supply Current * XC9509H/K/L IDD_VR - 40 80

Output Voltage VROUT(E) IROUT=30mA 3.234 3.300 3.366 V 2

Maximum Output Current Imax2 200 - - mA 2

Load Regulation U VROUT 1mA<IROUT<100mA - 15 50 mV 2

Dropout Voltage 1 (*6) Vdif 1 IROUT=30mA - 20 50 mV 2

Dropout Voltage 2 Vdif 2 IROUT=100mA - 60 110 mV 2

Line Regulation

(UV

IN・VROUT)

ROUT

ROUT=30mA

I

4.3V<

VIN<6.0V

- 0.05 0.25 %/V 2

U V

Current Limit Ilim2 VROUT=VROUT(E) x 0.9 240 300 - mA 7

Short-Circuit Current Ishort VROUT=VSS - 30 - mA 7

Ripple Rejection Rate PSRR

Output Voltage

Temperature Characteristics

(UTopr・V

U VROUT

ROUT)

IN=4.3VDC+0.5Vp-pAC,

I

ROUT=30mA, f=1kHz

ROUT=30mA

I

O

-40

C<Topr<85℃

- 60 - dB 12

-

±100

-

V

●Detector (2.7V product)

PARAMETER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS

Detect Voltage VDF(E) CE=0V 2.646 2.700 2.754 V 8

Hysteresis Range VHYS

Output Current

* XC9509A/D/H

Output Current

* XC9509B/C/E/F/K/L

Output Voltage

Temperature Characteristics

Test conditions: Unless otherwise stated:

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) / I

*4 : EFFI = { ( output voltage x output current ) / ( input voltage x input current) } x 100
*5 : Time until it short-circuits D

*6 : Vdif = (V
*7 : V
*8 : V

DC/DC : V
VR: V
VD: V

IN=3.6V [@ DCOUT:1.5V]
IN = 4.3V (VIN=VROUT(T) + 1.0V)
IN=5.0V

Common conditions for all test items: CE=V

●V

ROUT(T) : Setting Output Voltage

current limit pulse generating.

IN 1 = The input voltage when VROUT1 appears as input voltage is gradually decreased.
ROUT1 = A voltage equal to 98% of the output voltage whenever an amply stabilized IOUT {VROUT(T) + 1.0V} is input.

IN1

(*7)

- VROUT1

*9 : Current limit = When V

I

VD VIN=2.4V, VDOUT=0.5V, CE=0V 0.5 - - mA 9

I

VD VIN=2.4V, VDOUT=0.5V, CE=0V 1.0 - - mA 9

U VDF

(UTopr・V

LX (A)

COUT with GND through 1Ωof resistance from a state of operation and is set to DCOUT=0V from

(*8)

)

IN is low, limit current may not be reached because of voltage falls caused by ON resistance or

DF)

V

-40

HYS

O

(*11)

=[VDR(E)

C<Topr<85℃ -

- VDF(E)] / VDF(E) x 100

IN, MODE=0V

2 5 8 % 8

±100

-

serial resistance of coils.
*10: Integral latch circuit=latch time may become longer and latch operation may not work when V
*11: V

DR(E) = VD release voltage

IN is 3.0V or more.

*12: When temperature is high, a current of approximately 5.0μA (maximum) may leak.

*13: When using the IC with a regulator output at almost no load, a capacitor should be placed as close as possible between

A

VDD 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 V

DD level while the load of the DC/DC converter increases and the regulator output is at almost no load.

μA

ppm/

℃

ppm/

℃

Topr=25℃

CIRCUIT

1

2

CIRCUIT

8

5/41

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XC9509 Series

TEST CIRCUITS

Circuit 1 Supply Current, Stand-by Current, CE Current,

MODE Current

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 2 Output Voltage (VR), Load Regulation, Dropout Voltage,

Maximum Output Current, (MODE Voltage)

Circuit 4 Minimum Duty Cycle, Maximum Duty Cycle

Circuit 5 Lx ON Resistance

Circuit 6 Current Limit 1 (DC/DC)

6/41

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XC9509

TEST CIRCUITS (Continued

Circuit 7 Current Limit 2 (VR), Short Circuit Current (VR) Circuit 8 Detect Voltage, Release Voltage (Hysteresis Range)

Circuit 9 VD Output Current Circuit 10 Latch Time

* For the measurement of the VDD_Sense products,
the input voltage was controlled.

Circuit 11 Off-Leak Circuit 12 Ripple Rejection Rate

*

For the measurement of the VDD_Sense products,

the input voltage was controlled.

Series

7/41

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XC9509 Series

TYPICAL APPLICATION CIRCUIT

FOSC L

1.2MHz

600kHz

300kHz

MSOP-10 (TOP VIEW)

(CDRH4D28C, SUMIDA)

(CDRH5D28, SUMIDA)

(CDRH6D28, SUMIDA)

CIN CL1 CL2 (*2)

4.7μF

(ceramic, TAIYO YUDEN)

SD *1 : XB0ASB03A1BR (TOREX)

*1 The DC/DC converter of the XC9508 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 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 XC9509 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 V
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.

(ceramic, TAIYO YUDEN)

10μF

VROUT<2.0V

ROUT>2.0V

V

OUT pin through split resistors. Phase compensation is

4.7μF (ceramic, TAIYO YUDEN)

Vdif>1.0V
Vdif<

1.0V

1.0μF (ceramic, TAIYO YUDEN)

4.7μF (ceramic, TAIYO YUDEN)

<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.

8/41

4.7μH

10μH

22μH

■

)

OPERATIONAL EXPLANATION (Continued

●DC/DC Converter (Continued)

<PWM/PFM>
The PWM control of the XC9509A 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 XC9509H 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 XC9509 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

XC9509

Series

9/41

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)

XC9509 Series

OPERATIONAL EXPLANATION (Continued

●DC/DC Converter (Continued)

<Current Limit>

The current limiter circuit of the XC9509 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

●High Speed LDO Voltage Regulator

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 pin, or by restoring power to the V

IN 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 XC9509 series can be set at 1.1A for MSOP-10 package
and 0.7A for USP-10 package.

*

*

<U.V.L.O. Circuit>
When the V
pulse output caused by unstable operation of the internal circuitry. When the VI

IN pin voltage becomes 1.4 V or lower, the P-channel output driver transistor is forced OFF to prevent false

N 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 V

IN 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.

The voltage regulator block of the XC9509 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 VR

OUT 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 VR

OUT, 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 V

ROUT and GND pin are shorted, the load current of about 30mA flows.

10/41

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)

OPERATIONAL EXPLANATION (Continued

●Voltage Detector

The detector block of the XC9509 series detects output voltage from the VDOUT pin while sensing either VDD, DCOUT, or
VROUT internally.
(N-channel Open Drain Type)

<CE Pin Function>
The operation of the XC9509 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 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 the D

operation by inputting a high level signal to the CE pin. The input to the CE pin is a CMOS input and the sink current is

0μA (TYP.).

<MODE Pin Function>

The operation of the XC9509A to C series' voltage detector block will enter into stand-by mode when a high level signal is
input to the MODE pin. When a low level signal is input, the voltage regulator block will enter into stand-by mode.
However, if the IC enters into stand-by mode via the CE pin, the voltage regulator block also shuts down. Likewise, if
the XC9509D to F series enters into stand-by mode via the CE pin, the DC/DC converter block can also shut down.
With the XC9509H to L series control can be PWM control when the MODE pin is 'H' level and PWM/PFM automatic
switching control when the MODE pin is 'L' level.

NOTES ON USE

●Application Information

1. The XC9509 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.

COUT pin. The IC starts its

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 V

IN 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 V

IN 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.

XC9509

Series

●DC/DC Waveform (3.3V, 1.2MHz)

<External Components>
L :4.7μH(CDRH4D28C,SUMIDA)
CIN :4.7μF(ceramic)
CL :10μF(ceramic)

<External Components>

<External Components>

L :4.7μH(CDRH4D28C,SUMIDA)

L :4.7μH(CDRH4D28C,SUMIDA)

CIN :4.7μF(ceramic)

CIN :4.7μF(ceramic)

CL :10μF(ceramic)

CL :10μF(ceramic)

11/41

■

)

XC9509 Series

NOTES ON USE (Continued

●DC/DC Waveform (3.3V, 1.2MHz)(Continued)

5. The IC's DC/DC converter operates in synchronous mode when the coil current is in a continuous state and

Ics = (V

Ics: Switching current from synchronous rectification to non-synchronous rectification
OnDuty: OnDuty ratio of P-ch driver transistor (
L: Coil inductance value
Fosc: Oscillation frequency
ID

PFM Duty < Step down ratio = DC

PFM Duty: 30% (TYP.)

●DC/DC Waveform (1.8V, 600kHz) @ VIN=6.0V

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.

IN - DCOUT) x OnDuty / (L x Fosc)

.

=.step down ratio : DCOUT / VIN)

OUT: The DC/DC load current

6. When the XC9509H to L 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 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.

OUT / VIN x 100 (%)

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

.

<External Components>
L 10μH(CDRH5D28C,SUMIDA)
CIN :4.7μF(ceramic)
CL :10μF(ceramic)

Step Down ratio: 1.8V / 6.0V = 30%<PFM Duty 31%>

12/41

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)

NOTES ON USE (Continued

●DC/DC Waveform (3.3V, 1.2MHz) (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

RON=Rpon x P-chOnDuty / 100

+ Rnon x (1 – P-chOnDuty / 100)

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 = (V

IN - 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 VI

N 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 V

IN 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.

When using IC with a regulator output at almost no load, a capacitor should be placed as close as possible between

13.

AVDD and AGND (CIN2), connected with low impedance. Please also see the recommended pattern layout on page
14 for your reference. Should it not be possible to place the input capacitor nearby, the regulated output level may
increase up to the V

DD level while the load of the DC/DC converter increases and the regulator output is at almost

no load.

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

DC/DC power dissipation (when in synchronous operation) : PdDC/DC = ID

OUT

2

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.>)

15. The voltage detector circuit built-in the XC9509 series internally monitor the V

DD pin voltage, the DC/DC output pin

voltage and VR output pin voltage. For the XC9509B/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.

DF

≦

(Setting voltage on both the DCOUT voltage and the VROUT voltage)×85%*

V

* An assumed value of tolerance among the D

COUT voltage, the VROUT voltage, and the VD release voltage

(The VD detect voltage and hysteresis range).

XC9509

Series

13/41