XC9212A273DR [TOREX]
Switching Regulator/Controller;
| 型号： | XC9212A273DR |
| 厂家： | 
Torex Semiconductor |
| 描述： | Switching Regulator/Controller |
| 文件： | 总10页 (文件大小：92K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Driver Transistor Built-In Step-Down DC/DC Converters
Synchronous PWM, Non Synchronous PWM/PFM Switchable
XC9211/ 9212 Series
Preliminary
November 18, 2002 Ver. 2
Applications
P channel Driver Transistor Built-In
Synchronous (N channel Switching Transistor Built-in)
z Mobile phones (PDC, GSM, CDMA, IMT2000 etc.)
z PDA, Portable communication modem
z Portable game
Input Voltage Range
Output Voltage Range
Oscillation Frequency
Output Current
: 1.8V ~ 6.0V
: 0.9V ~ 4.0V
: 300kHz, 600kHz, 900kHz
: 400mA
z Camera, Digital camera
z Cordless phone
Maximum Duty Ratio
: 100%
z Note book computer
PWM/PFM Switching Control (XC9212 : Non Synchronous)
Ceramic Capacitor Compatible
Ultra Small Packages : SOT-25 & USP-6B
General Description
Features
The XC9211/9212 series is a group of synchronous-rectification
type DC/DC converters with a built-in 0.6 Ω P-channel driver
transistor and N-channel switching transistor, designed to allow
the use of ceramic capacitors. The ICs enable a high efficiency,
stable power supply with an output current of 400 mA to be
configured using only a coil and two capacitors connected
externally.
P ch driver Tr. Built-in : On resistance 0.6Ω
N ch driver Tr. Built-in : On resistance 0.6Ω (Synchronous)
Output Voltage Range : 0.9V ~ 4.0V (0.1V step)
Fixed output voltage accuracy ±2%
Minimum operating voltage is 1.8 V. Output voltage is internally
programmable in a range from 0.9 V to 4.0 V in increments of
0.1 V (accuracy: ± 2.0%). With the built-in oscillator, oscillation
frequency is selectable from 300 kHz, 600 kHz and 900 kHz to
make available the frequency best suited to your particular
application. As for operation mode, the XC9211 series is of a
synchronous-rectified PWM control type, while the XC9212
series can be manually switched between the PWM control
mode with synchronous rectification and the automatic
PWM/PFM switching control mode with non synchronous
rectification, allowing fast response, low ripple and high
efficiency over the full range of load (from light load to high
output current conditions). The soft start and current control
functions are internally optimized. During standby, all circuits
are shutdown to reduce current consumption to as low as 0.5 µA
or less. 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 1.6 V or lower. Two types of
packages, 250 mW (SOT-25) and 100 mW (USP-6B), are
available depending on applications.
Oscillation Frequency : 300kHz, 600kHz, 900kHz
Fixed oscillation frequency
accuracy ±15%
Stand-by function
: Istb = 0.5µA (max.)
Soft start circuit built-in
Current limiter circuit built-in
: 600mA
Typical Application Circuit
Electrical Characteristics XC9212A186
VOUT
L
Output Voltage 1.8V Fixed, FOSC : 600kHz
L=10µH (CDRH4D18)
CIN=4.7µF (Ceramic), CL=10µF (Ceramic)
VIN
(400mA)
1
2
3
VIN
5
Lx
(
)
SD *
100
CIN
(ceramic)
CL
(ceramic)
PWM/PFM Automatic Switch (Non-Synchronous)
VSS
80
60
CE/MODE
CE/ VOUT
MODE
4
40
PWM (Synchronous)
3.6V
VIN=2.4
10
Output Current IOUT (mA)
20
0
L
: 10µH (SUMIDA CDRH4D18)
: 10µH (Ceramic)
0.1
1
100
1000
CL
CIN
SD
: 4.7µH (Ceramic)
: CRS02 (TOSHIBA Schottky Diode)
* SD is externally set up for XC9212 series when used in non-synchronous PWM operation with large current.
1
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
Pin Configuration
Pin Assingment
Lx
5
VOUT
4
Pin Number
Pin Name
Functions
SOT-25
USP-6B
VIN
1
2
3
4
5
6
2, 5
4
Power Input
Ground
X
L
V
1
2
IN
V
VSS
6
5
VSS
SS
CE / MODE Chip Enable Mode Switch
VOUT3
4
CE/MODE
VOUT
LX
3
Output Voltage Sense
Switching Output
1
2
3
1
SS
VIN
V
CE/MODE
SOT-25
USP-6B
(Top View)
(Top View)
Product Classification
z Ordering Information
XC9211 123456
XC9212 123456
: PWM Control (Synchronous)
: Synchronous PWM / Non-synchronous PWM / PFM Automatic Switching, Manual Switching
(Synchronous PWM control : CE = "H")
(Non-synchronous PWM / PFM Automatic Switching : CE " M")
Symbol
Description
Transistor Built-in, Output voltage Internally set (VOUT product), Soft start Internally set.
A : Current Limiter 600mA
1
Denotes Output voltage :
2, 3
ex. ) 1.5V Output ꢀ 2= 1, 3= 5
Denotes Oscillation frequency :
3 : 300kHz
4
6 : 600kHz
9 : 900kHz
Denotes Package Types :
M : SOT-25
5
6
D : USP-6B
Denotes Device Orientation :
R : Embossed Tape : Standard Feed
L : Embossed Tape : Reverse Feed
2
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
Block Diagram
Phase
Compensation
VOUT
PWM
Comparator
Pch
Driver
Tr.
Buffer
Driver
Logic
VIN
LX
Error Amp.
Nch
SW
Tr.
Current
Limit & Feedback
Vref with
Soft Start,
CE
PWM/PFM
Selector
Ramp Wave
Generator,
OSC
U.V.L.O Comp.
U.V.L.O
CE/MODE
Control
CE/MODE
VSS
Logic
Absolute Maximum Ratings
O
Ta = 25 C
Parameter
Symbol
VIN
Ratings
Units
V
VIN pin voltage
VSS pin voltage
- 0.3 ~ + 6.5
- 0.3 ~ + 6.5
- 0.3 ~ + 6.5
- 0.3 ~ + 6.5
- 0.3 ~ + 6.5
± 600
VSS
V
VLX
Lx pin voltage
V
VOUT pin voltage
VOUT
VCE
ILX
V
CE / MODE pin voltage
Lx pin current
V
mA
SOT-25
250
100
Power Dissipation
Pd
mW
USP-6B
Operational Ambient Temperature
Storage Temperature
O
C
Topr
Tstg
- 40 ~ + 85
- 40 ~ + 125
O
C
3
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
Electrical Characteristics
XC9211A186, XC9212A186
Parameter
O
VOUT=1.8V, FOSC=600kHz, Ta=25 C
Symbol
VOUT1
Test Conditions
When connected to ext. compoments
IOUT=30mA
Min.
Typ.
Max.
Units
V
Output Voltage
1.764
1.800
1.836
VINmax
VINmin
Max. Input Voltage
Min. Operating Voltage
U.V.L.O Voltage
5.5
V
V
1.8
VUVLO
Voltage which LX pin voltage holding "L" level
When connected to ext. compoments
No ext. components,
1.4
V
IOUTmax
Max. Output Current
400
mA
Supply Current 1
Supply Current 2
IDD1
IDD2
160
30
µA
CE=VIN, VOUT=fixed voltage x 0.9
No ext. components,
µA
µA
CE=VIN, VOUT=fixed voltage x 1.1
No ext. components, CE=VOUT=0V
ISTB
Stand-by Current
0.5
When connected to ext. compoments
IOUT=30mA
Oscillation Frequency
FOSC
510
100
600
690
kHz
VOUT=VSS
Max. Duty Cycle
Min. Duty Cycle
MAXDTY
MINDTY
%
%
VOUT=VIN
0
PFM pulse width rate * 2
Efficiency *3
PFMDTY When connected to ext. components / No load
25
85
%
IOUT=100mA
CE=VIN, ILX=400mA, VOUT=fixed vol. x 0.9
CE=VIN, ILX=400mA, VOUT=fixed vol. x 1.1
VIN=5.0V
EFFI
RLXH
RLXL
ILIM
%
LX SW "H" On Resistance *4
LX SW "L" On Resistance *4
Current Limit
0.6
0.6
600
Ω
Ω
mA
No Ext. components
CE "H" Voltage
VCEH
1.2
V
When CE/MODE voltage is applied, LX determine "H"
VPWMH When connected to ext. components, IOUT=1mA
VPWML When Connected to ext. components, IOUT=1mA
VIN - 0.2
VIN - 1.0
PWM "H" Voltage *5
PWM "L" Voltage *5
V
V
No Ext. components
VCEL
CE "L" Voltage
VSS
0.3
V
When CE/MODE voltage is applied, LX determine "L"
ICEH
ICEL
CE=VIN=5.5V, VOUT=0V
µA
µA
CE "H" Current
CE "L" Current
- 0.1
- 0.1
0.1
0.1
CE=0V, VIN=5.5V, VOUT=0V
When connected to ext. components
Soft start time
TSS
6.0
ms
CE=0V ꢀ2.4V
*1 Unless otherwise stated, VIN = 3.6V
*2 PFM pulse width rate applies only to XC9212 series.
*3 EFFI = [ (Output Voltage x Output Current) / (Input Voltage x Input Current) ] x 100
*4 On resistance = VLX (measurement voltage) / 0.4A
The CE/MODE pin of the XC9212 series works also as an external PWM/PFM control switching pin. When the IC is in
*5
operation, control is switched to the PWM mode with synchronous rectification when the CE/MODE pin voltage is equal to
or higher than VIN minus 0.2 V, and to the automatic PWM/PFM switching mode with non synchronous rectification when
the CE/MODE pin voltage is equal to or lower than VIN minus 1.0 V and equal to or higher than VCEH.
4
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
Electrical Characteristics
XC9211A286, XC9212A286
Parameter
O
VOUT=2.8V, FOSC=600kHz, Ta=25 C
Symbol
VOUT1
Test Conditions
When connected to ext. compoments
IOUT=30mA
Min.
Typ.
Max.
Units
V
Output Voltage
2.744
2.800
2.856
VINmax
VINmin
Max. Input Voltage
Min. Operating Voltage
U.V.L.O Voltage
5.5
V
V
1.8
VUVLO
Voltage which LX pin voltage holding "L" level
When connected to ext. compoments
No ext. components,
1.4
V
IOUTmax
Max. Output Current
400
mA
Supply Current 1
Supply Current 2
IDD1
IDD2
160
30
µA
CE=VIN, VOUT=fixed voltage x 0.9
No ext. components,
µA
µA
CE=VIN, VOUT=fixed voltage x 1.1
No ext. components, CE=VOUT=0V
ISTB
Stand-by Current
0.5
When connected to ext. compoments
IOUT=30mA
Oscillation Frequency
FOSC
510
100
600
690
kHz
VOUT=VSS
Max. Duty Cycle
Min. Duty Cycle
MAXDTY
MINDTY
%
%
VOUT=VIN
0
PFM pulse width rate * 2
Efficiency *3
PFMDTY When connected to ext. components / No load
25
90
%
IOUT=100mA
CE=VIN, ILX=400mA, VOUT=fixed vol. x 0.9
CE=VIN, ILX=400mA, VOUT=fixed vol. x 1.1
VIN=5.0V
EFFI
RLXH
RLXL
ILIM
%
LX SW "H" On Resistance *4
LX SW "L" On Resistance *4
Current Limit
0.6
0.6
600
Ω
Ω
mA
No Ext. components
CE "H" Voltage
VCEH
1.2
V
When CE/MODE voltage is applied, LX determine "H"
VPWMH When connected to ext. components, IOUT=1mA
VPWML When connected to ext. components, IOUT=1mA
VIN - 0.2
VIN - 1.0
PWM "H" Voltage *5
PWM "L" Voltage *5
V
V
No Ext. components
VCEL
CE "L" Voltage
VSS
0.3
V
When CE/MODE voltage is applied, LX determine "L"
ICEH
ICEL
CE=VIN=5.5V, VOUT=0V
µA
µA
CE "H" Current
CE "L" Current
- 0.1
- 0.1
0.1
0.1
CE=0V, VIN=5.5V, VOUT=0V
When connected to ext. components
Soft start time
TSS
6.0
ms
CE=0V ꢀ2.4V
*1 Unless otherwise stated, VIN = 3.6V
*2 PFM pulse width rate applies only to XC9212 series.
*3 EFFI = [ (Output Voltage x Output Current) / (Input Voltage x Input Current) ] x 100
*4 On resistance = VLX (measurement voltage) / 0.4A
The CE/MODE pin of the XC9212 series works also as an external PWM/PFM control switching pin. When the IC is in
*5
operation, control is switched to the PWM mode with synchronous rectification when the CE/MODE pin voltage is equal to
or higher than VIN minus 0.2 V, and to the automatic PWM/PFM switching mode with non synchronous rectification when
the CE/MODE pin voltage is equal to or lower than VIN minus 1.0 V and equal to or higher than VCEH.
5
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
Electrical Characteristics
XC9211A336, XC9212A336
Parameter
O
VOUT=3.3V, FOSC=600kHz, Ta=25 C
Symbol
VOUT1
Test Conditions
When connected to ext. compoments
IOUT=30mA
Min.
Typ.
Max.
Units
V
Output Voltage
3.234
3.300
3.366
VINmax
VINmin
Max. Input Voltage
Min. Operating Voltage
U.V.L.O Voltage
5.5
V
V
1.8
VUVLO
Voltage which LX pin voltage holding "L" level
When connected to ext. compoments
No ext. components,
1.4
V
IOUTmax
Max. Output Current
400
mA
Supply Current 1
Supply Current 2
IDD1
IDD2
280
60
µA
CE=VIN, VOUT=fixed voltage x 0.9
No ext. components,
µA
µA
CE=VIN, VOUT=fixed voltage x 1.1
No ext. components, CE=VOUT=0V
ISTB
Stand-by Current
0.5
When connected to ext. compoments
IOUT=30mA
Oscillation Frequency
FOSC
510
100
600
690
kHz
VOUT=VSS
Max. Duty Cycle
Min. Duty Cycle
MAXDTY
MINDTY
%
%
VOUT=VIN
0
PFM pulse width rate * 2
Efficiency *3
PFMDTY When connected to ext. components / No load
25
90
%
IOUT=100mA
CE=VIN, ILX=400mA, VOUT=fixed vol. x 0.9
CE=VIN, ILX=400mA, VOUT=fixed vol. x 1.1
VIN=5.0V
EFFI
RLXH
RLXL
ILIM
%
LX SW "H" On Resistance *4
LX SW "L" On Resistance *4
Current Limit
0.6
0.6
600
Ω
Ω
mA
No Ext. components
CE "H" Voltage
VCEH
1.2
V
When CE/MODE voltage is applied, LX determine "H"
VPWMH When connected to ext. components, IOUT=1mA
VPWML When connected to ext. components, IOUT=1mA
VIN - 0.2
VIN - 1.0
PWM "H" Voltage *5
PWM "L" Voltage *5
V
V
No Ext. components
VCEL
CE "L" Voltage
VSS
0.3
V
When CE/MODE voltage is applied, LX determine "L"
ICEH
ICEL
CE=VIN=5.5V, VOUT=0V
µA
µA
CE "H" Current
CE "L" Current
- 0.1
- 0.1
0.1
0.1
CE=0V, VIN=5.5V, VOUT=0V
When connected to ext. components
Soft start time
TSS
6.0
ms
CE=0V ꢀ2.4V
*1 Unless otherwise stated, VIN = 5.0V
*2 PFM pulse width rate applies only to XC9212 series.
*3 EFFI = [ (Output Voltage x Output Current) / (Input Voltage x Input Current) ] x 100
*4 On resistance = VLX (measurement voltage) / 0.4A
The CE/MODE pin of the XC9212 series works also as an external PWM/PFM control switching pin. When the IC is in
*5
operation, control is switched to the PWM mode with synchronous rectification when the CE/MODE pin voltage is equal to
or higher than VIN minus 0.2 V, and to the automatic PWM/PFM switching mode with non synchronous rectification when
the CE/MODE pin voltage is equal to or lower than VIN minus 1.0 V and equal to or higher than VCEH.
6
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
Operational Explanation
Each unit of the XC9211/12 series consists of a reference voltage source, ramp wave circuit, error amplifier, PWM comparator,
phase compensation circuit, output voltage adjustment resistors, driver transistor, synchronous rectification switch, current
limiter circuit, U.V.L.O. circuit and others. The XC9211/12 series ICs compare, using the error amplifier, the voltage of the
internal voltage reference source with the feedback voltage from the VOUT pin through resistors R1 and R2. Phase
compensation is performed on the resulting error amplifier output, to input a signal to the PWM comparator to determine the
switching-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 ICs.
<Ramp Wave Circuit>
The ramp wave circuit determines switching frequency. The frequency is fixed internally, and selectable from 300 kHz, 600 kHz
and 900 kHz. 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 resistors (R1 and R2). 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.
<Current Limit>
The current limiter circuit of the XC9211/12 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
overcurrent state.
4When the overcurrent state is eliminated, the IC resumes normal operation.
The IC waits for the overcurrent state to end by repeating the steps 1through 3. If an overcurrent state continues for several
msec 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.
After being put into suspension mode, the IC can resume operation by turning the IC off once and then starting it up using 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
can be set at 600 mA.
Limit > # mS
Limit > # mS
Current Limit LEVEL
IOUT
0 mA
VSS
VOUT
LX
Restart
CE/MODE
VIN
7
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
<U.V.L.O. circuit>
When the VIN pin voltage becomes 1.6 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.
<CE/MODE Pin>
The XC9211/12 series will enter into shut down mode by inputting a low level signal to the CE/MODE pin. During shut down
mode, the current consumption of the IC becomes 0 µA (TYP.), with a state of high impedance at the LX pin and VOUT pin.
The IC starts its operation by inputting a high level signal to the CE/MODE pin.With the XC9212 series, the operation mode is
manually controlled through the CE/MODE pin. Inputting an intermediate voltage such as 0.5 x VIN voltage to the pin will make
the IC operate under PWM/PFM automatic switching mode while inputting the VIN voltage level will provide a synchronous
PWM fixed mode. The input of the CE/MODE pin is a CMOS input and the sink current is 0 µA (TYP.).
< XC9211 series CE/MODE pin >
(A)
SW_CE
ON
STATE
VIN
VIN
VDD
VDD
Chip Disable
R1
CE/
MODE
SW_CE
OFF
Synchronous PWM Control
CE/
MODE
IC inside
IC inside
(B)
SW_CE
R2
SW_CE
ON
STATE
Synchronous PWM Control
Chip Disable
( B )
( A )
OFF
XC9211 Series
Example: R1=R2=470kΩ
< XC9212 series CE/MODE pin >
(C)
SW_CE
ON
SW_PWM/PFM
STATE
VIN
VIN
VDD
VDD
-
Synchronous PWM Control
SW_PWM/
PFM
SW_
CE
RM1
CE/
MODE
Non-synchronous PWM/PFM automatic
switching control
OFF
OFF
ON
OFF
RM2
RM2
Chip Disable
CE/
MODE
SW_
CE
SW_PWM/
PFM
IC inside
IC inside
RM1
(D)
SW_CE
ON
SW_PWM/PFM
-
STATE
( D )
Chip Disable
( C )
Non-synchronous PWM/PFM automatic
switching control
XC9212 Series
OFF
OFF
ON
OFF
Synchronous PWM Control
Example: RM1=RM2=470kΩ
The intermediate voltage can be set by RM1 and RM2 as shown in the above circuit diagram. To reduce the consumption
current, R1,R2,RM1,RM2 can be set at a few hundred kohm each. For each switch, an open drain I/O port or Tr, etc. can be
used.
8
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
<PWM / PFM>
The XC9211 series features PWM control with synchronous rectification, while the XC9212 series allows manual switching
between the PWM control mode with synchronous rectification and the automatic PWM/PFM switching control mode with non
synchronous rectification.
Employing only synchronous-rectified PWM control mode, the XC9211 series is controlled with a constant frequency over a
wide range of load conditions extending from light to heavy. Constant frequency operation makes it easier to configure a filter
in the case of, for example, noise problems, but may decrease efficiency under light load conditions.
The XC9212 series can be switched between the PWM control mode with synchronous rectification and the automatic
PWM/PFM switching control mode with non synchronous rectification at any timing. Independent PFM control mode is not
available. The ICs can be fixed to constant frequency operation mode as necessary, enabling noise control and/or the like, as
well as high efficiency during PFM control under light load conditions. With the automatic PWM/PFM switching control function
with non synchronous rectification, the 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 below 25%, the PFM
circuit operates to output from the LX pin a pulse with an on-time rate fixed at 25%. During the PFM operation with 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.
On the XC9212 series ICs, the built in N-channel switching transistor for synchronous rectification remains OFF during non
synchronous rectification. During PFM operation, by using the parasitic diode of the N-channel switching transistor, the ICs
operate without any external Schottky diodes. However, in the case of PWM operation, use of an external Schottky diode is
recommended as necessary.
Typical Application Circuit
1
FOSC=900kHz product
L : 6.8µH (SUMIDA CDRH3D16)
CL : 10µH (ceramic)
VOUT
(400mA)
L
VIN
VIN
Lx
1
5
CIN : 4.7µH (ceramic)
CIN
(ceramic)
(
)
SD *
VSS
CL
SD : CRS02 (TOSHIBA schottky diode)
FOSC=600kHz product
2
(ceramic)
2
3
CE/MODE
CE/
MODE
VOUT
L : 10µH (SUMIDA CDRH4D18)
CL : 10µH (ceramic)
4
3
CIN : 4.7µH (ceramic)
SD : CRS02 (TOSHIBA schottky diode)
FOSC=300kHz product
L : 22µH (SUMIDA CDRH5D18)
CL : 10µH (ceramic)
CIN : 4.7µH (ceramic)
SD : CRS02 (TOSHIBA schottky diode)
* SD is externally set up for XC9212 series when used in non-
synchronous PWM operation with large current.
9
Driver Transistor Built-In Step-Down DC/DC Converters
XC9211/ 9212 Series
Preliminary
Synchronous PWM, Non Synchronous PWM/PFM Switchable
November 18, 2002 Ver. 2
Electrical Characteristics
(1) Output Voltage vs. Output Current
(2) Output Voltage vs. Input Current
XC9212A186MR (1.8V, 600kHz)
XC9212A186MR (1.8V, 600kHz)
L=10µH(CDRH4D18C), CIN=4.7µF(Ceramic)
CL=10µF x 2(Ceramic)
L=10µH(CDRH4D18C), CIN=4.7µF(Ceramic)
CL=10µF x 2(Ceramic)
2.1
Topr=25OC
VIN=3.6V
2.1
Topr=25OC
2.0
2
CE=VIN-1.0V : Non Synchronous
CE=VIN : Synchronous PWM Control
PWM/PFM Switchable
1.9
1.9
1.8
1.7
1.6
1.5
IOUT=100mA
1.8
1.7
CE=VIN : Synchronous
1.6
PWM Control
1.5
0.1
1
10
100
1000
1.5
2
2.5
3
3.5
4
4.5
5
Input Voltage VIN (V)
Output Current IOUT (mA)
(3) Oscillation Frequency vs. Input Voltage
(4) Efficiency vs. Output Current
XC9212A186MR (1.8V, 600kHz)
L=10µH(CDRH4D18C), CIN=4.7µF(Ceramic)
CL=10µF x 2(Ceramic)
XC9212A186MR (1.8V, 600kHz)
L=10µH(CDRH4D18C), CIN=4.7µF(Ceramic)
CL=10µF x 2(Ceramic)
100
90
80
70
60
50
40
30
20
10
0
700
650
600
550
500
CE=VIN-1.0V : Non Synchronous
PWM/PFM Switchable
Topr=25OC
CE=VIN : Synchronous PWM Control
IOUT=100mA
CE=VIN : Synchronous
PWM Control
Topr=25OC
VIN=3.6V
0.1
1
10
100
1000
1.5
2
2.5
3
3.5
4
4.5
5
Input Voltage VIN (V)
Output Current IOUT (mA)
(5) Ripple Voltage vs. Output Current
(6) Supply Current vs. Input Voltage
XC9212A186MR (1.8V, 600kHz)
XC9212A186MR (1.8V, 600kHz)
CIN=1µF
L=10µH(CDRH4D18C), CIN=4.7µF(Ceramic)
CL=10µF x 2(Ceramic)
When Oscillation is in holt condition
50
40
30
20
10
0
500
400
300
200
100
0
VIN=3.6V
Topr=25OC
Topr=25OC
CE=VIN-1.0V : Non Synchronous
PWM/PFM Switchable
IDD1:VOUT=0V
CE=VIN : Synchronous
PWM Control
IDD2:VOUT=VIN
0.1
1
10
100
1000
1.5
2
2.5
3
3.5
4
4.5
5
Output Current IOUT (mA)
Input Voltage VIN (V)
10
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