Download Ricoh RH5RH13B User's Manual

PWM STEP-UP DC/DC CONVERTER
RH5RH ×× 1A/ ××2B/ ××3B SERIES
APPLICATION MANUAL
ELECTRONIC DEVICES DIVISION
NO.EA-023-9803
NOTICE
1. The products and the product specifications described in this application manual are subject to change or discontinuation of production without notice for reasons such as improvement. Therefore, before deciding to use
the products, please refer to Ricoh sales representatives for the latest information thereon.
2. This application manual may not be copied or otherwise reproduced in whole or in part without prior written consent of Ricoh.
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4. The technical information described in this application manual shows typical characteristics of and example
application circuits for the products. The release of such information is not to be construed as a warranty of or a
grant of license under Ricoh's or any third party's intellectual property rights or any other rights.
5. The products listed in this document are intended and designed for use as general electronic components in
standard applications (office equipment, computer equipment, measuring instruments, consumer electronic
products, amusement equipment etc.). Those customers intending to use a product in an application requiring
extreme quality and reliability, for example, in a highly specific application where the failure or misoperation of
the product could result in human injury or death (aircraft, spacevehicle, nuclear reactor control system, traffic
control system, automotive and transportation equipment, combustion equipment, safety devices, life support
system etc.) should first contact us.
6. We are making our continuous effort to improve the quality and reliability of our products, but semiconductor
products are likely to fail with certain probability. In order prevent any injury to persons or damages to property
resulting from such failure, customers should be careful enough to incorporate safety measures in their design,
such as redundancy feature, fire-containment feature and fail-safe feature. We do not assume any liability or
responsibility for any loss or damage arising from misuse or inappropriate use of the products.
7. Anti-radiation design is not implemented in the products described in this application manual.
8. Please contact Ricoh sales representatives should you have any questions or comments concerning the products or the technical information.
June 1995
RH5RH SERIES
APPLICATION MANUAL
CONTENTS
OUTLINE ......................................................................................................1
FEATURES....................................................................................................1
APPLICATIONS .............................................................................................1
BLOCK DIAGRAM .........................................................................................2
SELECTION GUIDE .......................................................................................2
PIN CONFIGURATION ...................................................................................3
PIN DESCRIPTION ........................................................................................3
ABSOLUTE MAXIMUM RATINGS ...................................................................4
ELECTRICAL CHARACTERITICS ...................................................................5
OPERATION OF STEP-UP DC/DC CONVERTER ...........................................10
TYPICAL CHARACTERISTICS......................................................................13
1) Output Voltage vs. Output Current .......................................................................13
2) Efficiency vs. Output Current .............................................................................14
3) Supply Current (No Load) vs. Input Voltage ..............................................................15
4) Output Current vs. Ripple Voltage ........................................................................15
5) Start-up/Hold-on Voltage vs. Output Current (Topt=25˚C) ...............................................16
6) Output Voltage vs. Temperature .........................................................................17
7) Start-up Voltage vs. Temperature ........................................................................18
8) Hold-on Voltage vs. Temperature ........................................................................18
9) Supply Current 1 vs. Temperature .......................................................................18
10) Supply Current 2 vs. Temperature .......................................................................18
11) Lx Switching Current vs. Temperature ...................................................................18
12) Lx Leakage Current vs. Temperature ....................................................................18
13) Oscillator Frequency vs. Temperature....................................................................19
14) Oscillator Duty Cycle vs. Temperature ...................................................................19
15) Vlx Voltage Limit vs. Temperature ........................................................................20
16) EXT “H” Output Current vs. Temperature ................................................................20
17) EXT “L” Output Current vs. Temperature .................................................................20
18) Load Transient Response ................................................................................21
19) Distribution of Output Voltage ............................................................................22
20) Distribution of Oscillator Frequency ......................................................................22
TYPICAL APPLICATIONS ............................................................................23
• RH5RH ×× 1A .................................................................................................23
• RH5RH ×× 2B..................................................................................................23
• RH5RH ×× 3B..................................................................................................24
• CE pin Drive Circuit ............................................................................................22
APPLICATION CIRCUITS .............................................................................26
• 12V Step-up Circuit ............................................................................................26
• Step-down Circuit ..............................................................................................26
• Step-up/Step-down Circuit with Flyback .......................................................................27
PACKAGE DIMENSIONS ..............................................................................28
TAPING SPECIFICATIONS ...........................................................................28
PWM STEP-UP DC/DC CONVERTER
RH5RH ×× 1A/ ×× 2B/ ×× 3B SERIES
OUTLINE
The RH5RH ×× 1A/ ×× 2B/ ×× 3B Series are PWM Step-up DC/DC converter ICs by CMOS process.
The RH5RH ×× 1A IC consists of an oscillator, a PWM control circuit, a driver transistor (Lx switch), a reference voltage unit, an error amplifier, a phase compensation circuit, resistors for voltage detection, a soft-start circuit, and an Lx switch protection circuit. A low ripple, high efficiency step-up DC/DC converter can be constructed
of this RH5RH ×× 1A IC with only three external components, that is, an inductor, a diode and a capacitor.
These RH5RH×× 1A/ ×× 2B/×× 3B ICs can achieve ultra-low supply current (no load) –TYP. 15µA –by a newly developed PWM control circuit, equivalent to the low supply current of a VFM (chopper) Step-up DC/DC converter.
Furthermore, these ICs can hold down the supply current to TYP. 2µA by stopping the operation of the oscillator when the input voltage > (the output voltage set value + the dropout voltage by the diode and the inductor).
These RH5RH×× 1A/×× 2B/×× 3B Series ICs are recommendable to the user who desires a low ripple PWM
DC/DC converter, but cannot adopt a conventional PWM DC/DC converter because of its too large supply current.
The RH5RH×× 2B/×× 3B Series ICs use the same chip as that employed in the RH5RH×× 1A IC and are provided with a drive pin (EXT) for an external transistor. Because of the use of the drive pin (EXT), an external
transistor with a low saturation voltage can be used so that a large current can be caused to flow through the
inductor and accordingly a large output current can be obtained. Therefore, these RH5RH×× 2B/×× 3B Series ICs
are recommendable to the user who need a current as large as several tens mA to several hundreds mA.
The RH5RH×× 3B IC also includes an internal chip enable circuit so that it is possible to set the standby supply current at MAX. 0.5µA.
These RH5RH×× 1A/×× 2B/×× 3B ICs are suitable for use with battery-powered instruments with low noise
and low supply current.
FEATURES
• Small Number of External Components ..........Only an inductor, a diode and a capacitor (RH5RH ×× 1A)
• Low Supply Current ...........................................TYP. 15µA (RH5RH301A)
• Low Ripple and Low Noise
• Low Start-up Voltage (when the output current is 1mA) ..................MAX. 0.9V
• High Output Voltage Accuracy..........................±2.5%
• High Efficiency ...................................................TYP. 85%
• Low Temperature-Drift Coefficient of Output Voltage ......................TYP. ±50 ppm/˚C
• Soft-Start .............................................................MIN. 500µs
• Small Packages ...................................................SOT-89 (RH5RH ×× 1A, RH5RH ×× 2B),
SOT-89-5 (RH5RH ×× 3B)
APPLICATIONS
• Power source for battery-powered equipment.
• Power source for cameras, camcorders, VCRs, PDAs, electronic data banks,and hand-held communication
equipment.
• Power source for instruments which require low noise and low supply current, such as hand-held audio equip-
ment.
• Power source for appliances which require higher cell voltage than that of batteries used in the appliances.
1
RH5RH
BLOCK DIAGRAM
VLX limiter
Lx
Slow start
Vref
OUT
Buffer
Vss
Phase Comp.
LxSW
PWM control
–
+
EXT
OSC
Error Amp.
Chip Enable
CE
Error Amp. (Error Amplifier) has a DC gain of 80dB, and Phase Comp. (Phase Compensation Circuit)
provides the frequency characteristics including the 1st pole (fp=0.25Hz) and the zero point (fz=2.5kHz).
Furthermore, another zero point (fz=1.0kHz) is also obtained by the resistors and a capacitor connected to
the OUT pin.
(Note) Lx Pin ............only for RH5RH ×× 1A and RH5RH ×× 3B
EXT Pin .........only for RH5RH ×× 2B and RH5RH ×× 3B
CE Pin ...........only for RH5RH ×× 3B
SELECTION GUIDE
In RH5RH Series, the output voltage, the driver, and the taping type for the ICs can be selected at the user's
request. The selection can be made by designating the part number as shown below :
}
}
}
RH5RH ×××× – ×× ← Part Number
↑ ↑
↑
a b
c
Code
Description
a
Setting Output Voltage (VOUT):
Stepwise setting with a step of 0.1V in the range of 2.7V to 7.5V is possible.
b
Designation of Driver:
1A: Internal Lx Tr. Driver (Oscillator Frequency 50kHz)
2B: External Tr. Driver (Oscillator Frequency 100kHz)
3B: Internal Tr./External Tr. (selectively available) (Oscillator Frequency 100kHz, with chip
enable function)
c
Designation of Taping Type :
Ex. SOT-89 : T1, T2
SOT-89-5 : T1, T2
(refer to Taping Specifications)
“T1” is prescribed as a standard.
For example, the product with Output Voltage 5.0V, the External Driver (the Oscillator Frequency 100kHz)
and Taping Type T1, is designated by Part Number RH5RH502B-T1.
2
RH5RH
PIN CONFIGURATION
• SOT-89
• SOT-89-5
5
(mark side)
1
2
4
(mark side)
3
1
2
3
PIN DESCRIPTION
Pin No.
Symbol
Description
×× 1B
×× 2B
×× 3B
1
1
5
VSS
Ground Pin
2
2
2
OUT
Step-up Output Pin, Power Supply (for device itself)
3
—
4
Lx
—
3
3
EXT
—
—
1
CE
Switching Pin (Nch Open Drain)
External Tr. Drive Pin (CMOS Output)
Chip Enable Pin (Active Low)
3
RH5RH
ABSOLUTE MAXIMUM RATINGS
Symbol
Rating
Unit
Output Pin Voltage
+12
V
VLX
Lx Pin Voltage
+12
V
Note1
VEXT
EXT Pin Voltage
– 0.3 to VOUT+0.3
V
Note2
VCE
CE Pin Voltage
–0.3 to VOUT+0.3
V
Note3
ILX
Lx Pin Output Current
250
mA
Note1
IEXT
EXT Pin Current
±50
mA
Note2
PD
Power Dissipation
500
mW
VOUT
Item
Vss=0V
Topt
Operating Temperature Range
–30 to +80
˚C
Tstg
Storage Temperature Range
–55 to +125
˚C
Tsolder
Lead Temperature(Soldering)
(Note 1) Applicable to RH5RH ×× 1A and RH5RH ×× 3B.
(Note 3) Applicable to RH5RH ×× 3B.
Note
260˚C,10s
(Note 2) Applicable to RH5RH ×× 2B and RH5RH ×× 3B.
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under any
conditions. Moreover, such values for any two items must not be reached simultaneously. Operation above
these absolute maximum ratings may cause degradation or permanent damage to the device. These are stress
ratings only and do not necessarily imply functional operation below these limits.
4
RH5RH
ELECTRICAL CHARACTERISTICS
• RH5RH301A
VOUT=3.0V
Symbol
VOUT
Item
Conditions
Output Voltage
VIN
MIN.
TYP.
MAX.
Unit
2.925
3.000
3.075
V
8
V
0.9
V
Input Voltage
Vstart
Start-up Voltage
IOUT=1mA,VIN : 0→2V
Vhold
Hold-on Voltage
IOUT=1mA,VIN : 2→0V
IDD1
Supply Current 1
0.8
0.7
To be measured at OUT Pin
(excluding Switching Current)
Note
V
15
25
µA
2
5
µA
To be measured at OUT Pin
IDD2
Supply Current 2
(excluding Switching Current)
VIN=3.5V
ILX
Lx Switching Current
ILXleak
Lx Leakage Current
fosc
Oscillator Frequency
Maxdty
η
Oscillator Maximum Duty
Cycle
VLX=0.4V
Soft-Start Time
mA
VLX=6V,VIN=3.5V
on (VLX “L” ) side
Efficiency
tstart
60
Time required for the rising
0.5
µA
40
50
60
kHz
70
80
90
%
70
85
%
0.5
2.0
ms
Note1
0.65
0.8
V
Note2
of VOUT up to 3V.
VLXlim
VLX Voltage Limit
Lx Switch ON
1.0
Unless otherwise provided, VIN=1.8V, VSS=0V, IOUT=10mA, Topt=25˚C, and use External Circuit of Typical
Application (FIG. 1).
(Note 1) Soft-Start Circuit is operated in the following sequence :
(1) VIN is applied.
(2) The voltage (Vref) of the reference voltage unit is maintained at 0V for about 200µs after the application of VIN.
(3) The output of Error Amp. is raised to “H” level during the maintenance of the voltage (Vref) of the reference voltage unit.
(4) After the rise of Vref, the output of Internal Error Amp. is gradually decreased to an appropriate value by the function of Internal Phase
Compensation Circuit, and the Output Voltage is gradually increased in accordance with the gradual decrease of the output of Internal Error
Amp.
(Note 2) ILX is gradually increased after Lx Switch is turned ON. In accordance with the increase of ILX, VLX is also increased. When VLX reaches VLXlim,
Lx Switch is turned OFF by an Lx Switch Protection Circuit.
5
RH5RH
• RH5RH501A
VOUT=5.0V
Symbol
VOUT
Item
Conditions
Output Voltage
VIN
MIN.
TYP.
MAX.
Unit
4.875
5.000
5.125
V
8
V
0.9
V
Input Voltage
Vstart
Start-up Voltage
Iout=1mA,Vin:0→2V
Vhold
Hold-on Voltage
Iout=1mA,Vin:2→0V
IDD1
Supply Current 1
0.8
0.7
To be measured at OUT Pin
(excluding Switching Current)
Note
V
30
45
µA
2
5
µA
To be measured at OUT Pin
IDD2
Supply Current 2
(excluding Switching Current)
VIN=5.5V
ILX
Lx Switching Current
ILXleak
Lx Leakage Current
fosc
Oscillator Frequency
Maxdty
η
tstart
Oscillator Maximum Duty
Cycle
VLX=0.4V
mA
VLX=6V,VIN=5.5V
on (VLX “L” ) side
Efficiency
Soft-Start Time
80
Time required for the rising
0.5
µA
40
50
60
kHz
70
80
90
%
70
85
%
0.5
2.0
ms
Note1
0.65
0.8
V
Note2
of VOUT up to 5V.
VLXlim
VLX Voltage Limit
Lx Switch ON
1.0
Unless otherwise provided, VIN=3V, Vss=0V, IOUT=10mA, Topt=25˚C, and use External Circuit of Typical
Application (FIG. 1).
(Note 1) Soft-Start Circuit is operated in the following sequence :
(1) VIN is applied.
(2) The voltage (Vref) of the reference voltage unit is maintained at 0V for about 200µs after the application of VIN.
(3) The output of Error Amp. is raised to “H” level during the maintenance of the voltage (Vref) of the reference voltage unit.
(4) After the rise of Vref, the output of Internal Error Amp. is gradually decreased to an appropriate value by the function of Internal Phase
Compensation Circuit, and the Output Voltage is gradually increased in accordance with the gradual decrease of the output of Internal Error
Amp.
(Note 2) ILX is gradually increased after Lx Switch is turned ON. In accordance with the increase of ILX, VLX is also increased. When VLX reaches VLXlim,
Lx Switch is turned OFF by an Lx Switch Protection Circuit.
6
RH5RH
• RH5RH302B
VOUT=3.0V
Symbol
VOUT
VIN
Vstart
Item
Conditions
Output Voltage
MIN.
TYP.
MAX.
Unit
2.925
3.000
3.075
V
8
V
Input Voltage
Oscillator Start-up Voltage
EXT no load,VOUT :0→2V
0.7
0.8
V
IDD1
Supply Current 1
EXT no load,VOUT=2.88V
30
50
µA
IDD2
Supply Current 2
EXT no load,VOUT=3.5V
2
5
µA
IEXTH
EXT “H” Output Current
VEXT=VOUT–0.4V
–1.5
mA
IEXTL
EXT “L” Output Current
VEXT=0.4V
1.5
mA
fosc
Maxdty
Oscillator Frequency
100
120
kHz
70
80
90
%
0.5
2.0
Oscillator Maximum Duty
VEXT “H” side
Cycle
tstart
80
Note
Soft-Start Time
Time required for the rising
ms
Note1
of VOUT up to 3V
Unless otherwise provided, VIN=1.8V, Vss=0V, IOUT=10mA, Topt=25˚C, and use External Circuit of Typical
Application (FIG. 2).
VOUT=5.0V
• RH5RH502B
Symbol
VOUT
VIN
Vstart
Item
Conditions
Output Voltage
MIN.
TYP.
MAX.
Unit
4.875
5.000
5.125
V
8
V
Input Voltage
Oscillator Start-up Voltage
EXT no load,VOUT :0→2V
0.7
0.8
V
IDD1
Supply Current 1
EXT no load,VOUT=4.8V
60
90
µA
IDD2
Supply Current 2
EXT no load,VOUT=5.5V
2
5
µA
IEXTH
EXT “H” Output Current
VEXT=VOUT–0.4V
–2
mA
IEXTL
EXT “L” Output Current
VEXT=0.4V
2
mA
fosc
Maxdty
Oscillator Frequency
100
120
kHz
70
80
90
%
0.5
2.0
Oscillator Maximum Duty
Cycle
tstart
80
Note
Soft-Start Time
VEXT “H” side
Time required for the rising
ms
Note1
of VOUT up to 5V
Unless otherwise provided, VIN=3V, Vss=0V, IOUT=10mA, Topt=25˚C and use External Circuit of Typical
Application (FIG. 2).
(Note 1) refer to page 5 (Note 1)
7
RH5RH
• RH5RH303B
VOUT=3.0V
Symbol
VOUT
Item
Conditions
Output Voltage
VIN
MIN.
TYP.
MAX.
Unit
2.925
3.000
3.075
V
8
V
0.9
V
Input Voltage
Vstart
Start-up Voltage
IOUT=1mA,VIN : 0→2V
Vhold
Hold-on Voltage
IOUT=1mA,VIN : 2→0V
η
Efficiency
0.8
0.7
70
V
85
%
IDD1
Supply Current 1
To be measured at OUT pin
30
50
µA
IDD2
Supply Current 2
To be measured at OUT pin
VIN=3.5V
2
5
µA
ILX
Lx Switching Current
VLX=0.4V
60
mA
ILXleak
Lx Leakage Current
VLX=6V,VIN=3.5V
IEXTH
EXT “H” Output Current
VEXT=VOUT–0.4V
–1.5
mA
IEXTL
EXT “L” Output Current
VEXT=0.4V
1.5
mA
VCEH1
CE “H” Level 1
VOUT≥1.5V
VOUT–0.4
V
VCEL1
CE “L” Level 1
VOUT≥1.5V
VCEH2
CE “H” Level 2
0.8V≤VOUT<1.5V
VCEL2
CE “L” Level 2
0.8V≤VOUT<1.5V
0.1
V
0.5
µA
ICEH
CE “H” Input Current
CE=3V
ICEL
CE “L” Input Current
CE=0V
fosc
Oscillator Frequency
Maxdty
Oscillator Maximum Duty
Cycle
tstart
Soft-Start Time
VLXlim
VLX Voltage Limit
Note
0.5
0.4
VOUT–0.1
µA
V
V
–0.5
µA
80
100
120
kHz
on (VLX “L” )side
70
80
90
%
Time required for the rising
of VOUT up to 3V.
0.5
2.0
Lx Switch ON
0.65
0.8
1.0
ms
Note1
V
Note2
Unless otherwise provided, VIN=1.8V, VSS=0V, IOUT=10mA, Topt=25˚C, and use External Circuit of Typical
Application (FIG. 3).
(Note 1) Soft-Start Circuit is operated in the following sequence :
(1) VIN is applied.
(2) The voltage (Vref) of the reference voltage unit is maintained at 0V for about 200µs after the application of VIN.
(3) The output of Error Amp. is raised to “H” level during the maintenance of the voltage (Vref) of the reference voltage unit.
(4) After the rise of Vref, the output of Internal Error Amp. is gradually decreased to an appropriate value by the function of Internal Phase Com
pensation Circuit, and the Output Voltage is gradually increased in accordance with the gradual decrease of the output of Internal Error Amp.
(Note 2) ILX is gradually increased after Lx Switch is turned ON. In accordance with the increase of ILX, VLX is also increased. When VLX reaches VLXlim,
Lx Switch is turned OFF by an Lx Switch Protection Circuit.
8
RH5RH
• RH5RH503B
VOUT=5.0V
Symbol
VOUT
Item
Conditions
Output Voltage
VIN
MIN.
TYP.
MAX.
Unit
4.875
5.000
5.125
V
8
V
0.9
V
Input Voltage
Vstart
Start-up Voltage
IOUT=1mA,VIN : 0→2V
Vhold
Hold-on Voltage
IOUT=1mA,VIN : 2→0V
η
Efficiency
0.8
0.7
70
V
85
%
IDD1
Supply Current 1
To be measured at OUT pin
60
90
µA
IDD2
Supply Current 2
To be measured at OUT pin
VIN=5.5V
2
5
µA
ILX
Lx Switching Current
VLX=0.4V
80
mA
ILXleak
Lx Leakage Current
VLX=6V,VIN=5.5V
IEXTH
EXT “H” Output Current
VEXT=VOUT–0.4V
–2.0
mA
IEXTL
EXT “L” Output Current
VEXT=0.4V
2.0
mA
VCEH1
CE “H” Level 1
VOUT≥1.5V
VOUT–0.4
V
VCEL1
CE “L” Level 1
VOUT≥1.5V
VCEH2
CE “H” Level 2
0.8V≤VOUT<1.5V
VCEL2
CE “L” Level 2
0.8V≤VOUT<1.5V
0.1
V
0.5
µA
ICEH
CE “H” Input Current
CE=5V
ICEL
CE “L” Input Current
CE=0V
fosc
Oscillator Frequency
Maxdty
Oscillator Maximum Duty
Cycle
tstart
Soft-Start Time
VLXlim
VLX Voltage Limit
Note
0.5
0.4
VOUT–0.1
µA
V
V
–0.5
µA
80
100
120
kHz
on (VLX “L” )side
70
80
90
%
Time required for the rising
of VOUT up to 5V.
0.5
2.0
Lx Switch ON
0.65
0.8
1.0
ms
Note1
V
Note2
Unless otherwise provided, VIN=3V, VSS=0V, IOUT=10mA, Topt=25˚C, and use External Circuit of Typical
Application (FIG. 3).
(Note 1) Soft-Start Circuit is operated in the following sequence :
(1) VIN is applied.
(2) The voltage (Vref) of the reference voltage unit is maintained at 0V for about 200µs after the application of VIN.
(3) The output of Error Amp. is raised to “H” level during the maintenance of the voltage (Vref) of the reference voltage unit.
(4) After the rise of Vref, the output of Internal Error Amp. is gradually decreased to an appropriate value by the function of Internal Phase Com
pensation Circuit, and the Output Voltage is gradually increased in accordance with the gradual decrease of the output of Internal Error Amp.
(Note 2) ILX is gradually increased after Lx Switch is turned ON. In accordance with the increase of ILX, VLX is also increased. When VLX reaches VLXlim,
Lx Switch is turned OFF by an Lx Switch Protection Circuit.
9
RH5RH
OPERATION OF STEP-UP DC/DC CONVERTER
Step-up DC/DC Converter charges energy in the inductor when Lx Transistor (LxTr) is on, and discharges the
energy with the addition of the energy from Input Power Source thereto, so that a higher output voltage than the
input voltage is obtained.
The operation will be explained with reference to the following diagrams :
< Basic Circuits >
< Current through L >
IL
i2
L
VIN
ILmax
IOUT
SD
ILmin
topen
VOUT
i1
Lx Tr
CL
t
toff
ton
T=1/fosc
Step 1 : LxTr is turned ON and current IL (= i1 ) flows, so that energy is charged in L. At this moment, IL(=i1 ) is
increased from ILmin (= 0) to reach ILmax in proportion to the on-time period (ton) of LxTr.
Step 2 : When LxTr is turned OFF, Schottky diode (SD) is turned ON in order that L maintains IL at ILmax, so
that current IL (= i2) is released.
Step 3 : IL (=i2) is gradually decreased, and in the case of discontinuous mode, IL reaches ILmin (=0) after a time
period of topen, so that SD is turned OFF. However, in the case of a continuous mode which will be mentioned
later,the time period (toff) runs out before IL reaches ILmin (=0), so that LxTr is turned ON in the next
cycle, and SD is turned OFF. In this case, ILmin does not reach zero, and IL (=i1) increases from ILmin (> 0).
In the case of PWM control system, the output voltage is maintained constant by controlling the on-time period (ton), with the oscillator frequency (fosc) being maintained constant.
• Discontinuous Conduction Mode and Continuous Conduction Mode
In the above two diagrams, the maximum value (ILmax) and the minimum value (ILmin) of the current which
flows through the inductor are the same as those when LxTr is ON and also when LxTr is OFF.
The difference between ILmax and ILmin, which is represented by ∆I, is :
∆I=ILmax–ILmin=VIN · ton/L=(VOUT–VIN) · topen/L .........................................Equation 1
wherein T=1/fosc=ton+toff
duty (%)=ton/T · 100=ton · fosc · 100
topen≤toff
In Equation 1, VIN · ton/L and (VOUT–VIN) · topen/L are respectively show the change in the current at ON, and the
change in the current at OFF.
10
RH5RH
When the output current (IOUT) is relatively small, topen<toff as illustrated in the above diagram. In this case,
the energy charged in the inductor during the time period of ton is discharged in its entirely during the time period of toff, so that ILmin becomes zero (ILmin=0). When IOUT is gradually increased, topen eventually becomes
equal to toff (topen=toff), and when IOUT is further increased. ILmin becomes larger than zero (ILmin>0). The
former mode is referred to as the discontinuous mode and the latter mode is referred to as the continuous mode.
In the continuous mode, when Equation 1 is solved for ton and the solution is tonc,
tonc =T · (1–VIN/VOUT) ................................................................................................Equation 2
When ton<tonc, the mode is the discontinuous mode, and when ton=tonc, the mode is the continuous mode.
• Output Current in Discontinuous Mode
In the discontinuous mode, when LxTr is on, the energy PON charged in the inductor is provided by Equation 3
as follows :
ton
PON=∫ 0ton VIN · IL (t) dt =∫ 0 (VIN2 · t/L) dt
=VIN2 · ton2/(2 · L) .................................................................................................Equation 3
In the case of the step-up DC/DC converter, the energy is also supplied from the input power source at the time
of OFF.
Thus, POFF=∫ 0topen VIN · IL (t) dt =∫ 0topen ((VOUT–VIN) · t/L)dt
=VIN · (VOUT–VIN) · topen2/(2 · L)
Here, topen=VIN · ton/(VOUT–VIN) from Equation 1, and when this is substituted into the above equation.
=VIN3 · ton2/(2 · L · (VOUT–VIN) ..........................................................................Equation 4
Input power is (PON+POFF)/T. When this is converted in its entirely to the output.
PIN=(PON+POFF)/T=VOUT · IOUT=POUT .....................................................................Equation 5
Equation 6 can be obtained as follows by solving Equation 5 for IOUT by substituting Equations 3 and 4 into
Equation 5 :
IOUT=VIN2 · ton2/(2 · L · T · (VOUT–VIN)) ..................................................................... Equation 6
The peak current which flows through L · LxTr · SD is
ILmax=VIN · ton/L ...................................................................................................... Equation 7
11
RH5RH
Therefore it is necessary that the setting of the input/output conditions and the selection of peripheral components should be made with ILmax taken into consideration.
• Output Current in Continuous Conduction Mode
When the operation enters into the continuous conduction mode by increasing the IOUT, ILmin becomes equal
to Iconst (> 0), and this current always flows through the inductor. Therefore, VIN · Iconst is added to PIN in
Equation 5.
Thus, PIN=VIN · Iconst+(PON+POFF)/T=VOUT · IOUT=POUT
When the above Equation is solved for IOUT,
IOUT=VIN2 · tonc2/(2 · L · T · (VOUT–VIN))+VIN · Iconst/VOUT ............................................Equation 8
The peak current which flows through L · LxTr · SD is
ILmax=VIN · ton/L+Iconst ...................................................................................................Equation 9
From Equations 6 and 9, the larger the value of L, the smaller the load current at which the operation enters
into the continuous mode, and the smaller the difference between ILmax and ILmin, and the smaller the value of
ILmax.
Therefore, when the load current is the same, the larger the value of L, the easier the selection of peripheral
components with a small allowable current becomes, and the smaller the ripple of the peripheral components can
be made. In this case, however, it must be noted from Equation 6 that IOUT becomes small when the allowable current of the inductor is small or when VIN is so small that the operation cannot enter into the continuous mode.
HINTS
The above explanation is directed to the calculation in an ideal case where there is no energy loss caused by the
resistance in the external components and LxSW. In an actual case, the maximum output current will be 50
to 80% of the above calculated maximum output current. In particular, care must be taken because VIN is
decreased in an amount corresponding to the voltage drop caused by LxSW when IL is large or VIN is low.
Furthermore, it is required that with respect to VOUT, Vf of the diode (about 0.3V in the case of a Schottky type
diode) be taken into consideration.
12
RH5RH
TYPICAL CHARACTERISTICS
1) Output Voltage vs. Output Current
Output Voltage VOUT(V)
3.0
2.9
2.8
2.7
1.5V
RH5RH301A
L=120µH
3.1
Output Voltage VOUT(V)
RH5RH301A
3.1
2.0V
2.6
3.0
2.9
2.8
2.7
1.5V
2.6
VIN=1.0V
VIN =1.0V
0
20
40
Output Current IOUT(mA)
RH5RH501A
5.2
4.8
4.6
3.0V
4.0V
4.4
4.2
4.0
0
VIN=
1.0V
50
100
Output Current IOUT(mA)
10
40
20
30
Output Current IOUT(mA)
RH5RH501A
L=120µH
5.0
2.0V
0
60
5.2
Output Voltage VOUT(V)
Output Voltage VOUT(V)
2.0V
2.5
2.5
4.0V
4.6
3.0V
2.0V
4.4
4.2
VIN=1.0V
50
100
Output Current IOUT(mA)
2.0V
Output Voltage VOUT(V)
1.5V
2.5V
2.9
VIN=0.9V
2.8
0
200
400
Output Current IOUT(mA)
600
150
L=28µH
5.2
3.0V
3.0
L=270µH
RH5RH502B
L=28µH
3.1
60
4.8
4.0
0
150
50
5.0
RH5RH302B
Output Voltage VOUT(V)
L= 270µH
5.0
4.0V
2.0V
4.8
4.6
4.4
0
VIN=1.5V
500
Output Current I OUT(mA)
1000
13
RH5RH
2) Efficiency vs. Output Current
RH5RH301A
Efficiency η (%)
Efficiency η (%)
2.0V
70
1.5V
60
VIN=1.0V
50
0
10
20
Output Current IOUT(mA)
RH5RH501A
VIN=1.0V
1.5V
10
30
20
Output Current IOUT(mA)
40
L=270µH
100
90
Efficiency η (%)
Efficiency η (%)
60
RH5RH501A
L=120µH
4.0V
80
3.0V
70
2.0V
60
VIN=1.0V
50
80
70
60
4.0V
VIN=
1.0V
3.0V
2.0V
50
40
0
50
100
Output Current I OUT(mA)
RH5RH302B
100
40
0
150
50
100
Output Current IOUT(mA)
RH5RH502B
L = 28µH
100
80
150
L=28µH
80
2.0V
60
Efficiency η (%)
Efficiency η (%)
2.0V
70
40
0
30
90
14
80
50
100
2.5V
1.5V
40
VIN=0.9V
20
0
L=270µH
100
90
80
40
RH5RH301A
L=120µH
90
3.0V
60
4.0V
2.0V
40
VIN=1.5V
20
0
0
200
400
Output Current IOUT(mA)
600
0
500
Output Current IOUT(mA)
1000
RH5RH
3) Supply Curret (No Load) vs. Input Voltage
RH5RH301A
70
RH5RH301A
L=120µH
70
60
Supply Current IIN (µA)
Supply Current IIN (µA)
60
50
40
30
20
10
0
1.0
1.2
1.6
1.4
Input Voltage VIN(V)
RH5RH501A
1.8
100
50
2
3
Input Voltage VIN(V)
30
20
10
1.2
1.4
1.6
Input Voltage VIN(V)
200
0
1
40
RH5RH501A
L=120µH
150
50
0
1.0
2.0
Supply Current IIN (µA)
200
Supply Current IIN (µA)
L=270µH
2.0
L=270µH
150
100
50
0
4
1.8
1
2
3
Input Voltage VIN(V)
4
4) Output Current vs.Ripple Voltage
70
2.0V
60
3.0V
50
VIN=0.9V
40
30
20
10
0
1
RH5RH501A
L=120µH
5 10 20 30 40 50 60 70 80 90 100
Output Current IOUT(mA)
100
Ripple Voltage Vr (mV p-p)
Ripple Voltage Vr (mV p-p)
RH5RH301A
80
L=120µH
90
4.0V
80
3.0V
70
2.0V
60
50
40 VIN=0.9V
30
20
10
0
1 5 10 20 30 40 50 60 70 80 90 100
Output Current IOUT(mA)
15
RH5RH
RH5RH301A
Ripple Voltage Vr (mV p-p)
Ripple Voltage Vr (mV p-p)
60
50
3.0V
40
VIN=0.9V
2.0V
30
RH5RH501A
L=270µH
70
20
10
80
70
60
4.0V
50
3.0V
40
30
2.0V
20
VIN=0.9V
10
0
0
20 30 40 50 60
Output Current IOUT(mA)
10
70
RH5RH302B
VIN=0.9V
2.0V
3.0V
50
40
30
20
10
0
1
50
100
150
Output Current IOUT(mA)
20 30 40 50 60 70
Output Current IOUT(mA)
10
RH5RH502B
L=28µH
70
60
1
80
120
Ripple Voltage Vr (mV p-p)
1
Ripple Voltage Vr (mV p-p)
L=270µH
90
L=28µH
2.0V
100
3.0V
80
60
4.0V
40
VIN=0.9V
20
0
1
200
80
50
100
150
200
Output Current IOUT(mA)
250
16
RH5RH301A
L=120µH
1.4
1.2
1.0
Vstart
0.8
0.6
Vhold
0.4
0.2
0
0
20
10
Output Current IOUT(mA)
30
Start-up/Hold-on Voltage Vstart/Vhold (V)
Start-up/Hold-on Voltage Vstart/Vhold (V)
5) Start-up/Hold-on Voltage vs. Output Current (Topt=25˚C)
RH5RH501A
L=120µH
1.6
1.4
1.2
Vstart
1.0
0.8
0.6
Vhold
0.4
0.2
0
0
20
10
Output Current IOUT(mA)
30
RH5RH302B
L=28µH
1.4
1.2
1.0
Vstart
0.8
0.6
0.4
Vhold
0.2
0
0
20
40
60
80
Output Current IOUT(mA)
100
Start-up/Hold-on Voltage Vstart/Vhold (V)
Start-up/Hold-on Voltage Vstart/Vhold (V)
RH5RH
RH5RH502B
L=28µH
1.4
1.2
Vstart
1.0
0.8
0.6
Vhold
0.4
0.2
0
80
20
40
60
Output Current IOUT(mA)
0
100
6) Output Voltage vs.Temperature
RH5RH301A
3.1
3.0
2.9
2.8
2.7
–40
–20
0
20
40
60
Temperature Topt(˚C)
RH5RH302B
5.2
80
IOUT=10mA
VIN=2V
L=28µH
3.1
3.0
2.9
2.8
–20
60
0
20
40
Temperature Topt(˚C)
80
100
IOUT=10mA
VIN=3V
L=120µH
5.1
5.0
4.9
4.8
4.7
–40
100
–20
0
20
40
60
Temperature Topt(˚C)
RH5RH502B
5.2
Output Voltage VOUT (V)
Output Voltage VOUT (V)
3.2
2.7
–40
RH5RH501A
Output Voltage VOUT (V)
Output Voltage VOUT (V)
3.2
IOUT=10mA
VIN=2V
L=120µH
80
100
IOUT=10mA
VIN=3V
L=28µH
5.1
5.0
4.9
4.8
4.7
–40
–20
0
20
40
60
Temperature Topt(˚C)
80
100
17
RH5RH
7) Start-up Voltage vs. Temperature
8) Hold-on Voltage vs. Temperature
RH5RH501A
RH5RH501A
1.0
Hold-on Voltage Vhold(V)
Start-up Voltage Vstart(V)
1.2
1.0
0.8
0.6
0.4
0.2
0
–40
–20
40
0
20
Temperature Topt(˚C)
60
0.6
0.4
0.2
0
–40
80
9) Supply Current 1 vs.Temperature
0.8
–20
Supply Current 2 IDD2(µA)
Supply Current 1 IDD1(µA)
80
60
40
20
–20
0
20
40
Temperature Topt(˚C)
60
80
4
3
2
1
0
–40
80
–20
RH5RH501A
Lx Leakage Current ILXleak (µA)
150
125
100
75
50
25
–20
0
20
40
Temperature Topt(˚C)
0
20
40
Temperature Topt(˚C)
12) Lx Leakage Current vs.Temperature
RH5RH501A
Lx Switching Current ILX (mA)
60
5
11) Lx Switching Current vs.Temperature
18
80
RH5RH501A
100
0
–40
60
10) Supply Current 2 vs.Temperature
RH5RH501A
0
–40
20
40
0
Temperature Topt(˚C)
60
80
1.0
0.8
0.6
0.4
0.2
0
–40
–20
0
20
40
Temperature Topt(˚C)
60
80
RH5RH
13) Oscillator Frequency vs. Temperature
100
90
80
70
60
50
40
30
20
10
0
–40
–20
40
0
60
20
Temperature Topt(˚C)
RH5RH302B
140
80
100
IOUT=10mA
VIN=2V
L=28µH
120
100
80
60
40
20
0
–40
RH5RH501A
–20
0
20
40
60
Temperature Topt(˚C)
80
100
90
80
70
60
50
40
30
20
10
0
–40
–20
20
40
60
0
Temperature Topt(˚C)
RH5RH502B
Oscillator Frequency fosc(kHz)
Oscillator Frequency fosc(kHz)
IOUT=10mA
VIN=2V
L=120µH
Oscillator Frequency fosc(kHz)
Oscillator Frequency fosc(kHz)
RH5RH301A
100
140
IOUT=10mA
VIN=3V
L=120µH
80
100
IOUT=10mA
VIN=3V
L=28µH
120
100
80
60
40
20
0
–40
–20
0
20
40
60
Temperature Topt(˚C)
80
100
14) Oscillator Duty Cycle vs. Temperature
100
90
80
70
60
50
–40
RH5RH501A
IOUT=10mA
VIN=2V
L=120µH
Oscillator Duty Cycle Maxdty(%)
Oscillator Duty Cycle Maxdty(%)
RH5RH301A
–20
0
20
40
Temperature Topt(˚C)
60
80
100
IOUT=10mA
VIN=3V
L=120µH
90
80
70
60
50
–40
–20
0
20
40
Temperature Topt(˚C)
60
80
19
RH5RH
100
IOUT=10mA
VIN=2V
L=28µH
90
80
70
60
50
–40
RH5RH502B
Oscillator Duty Cycle Maxdty(%)
Oscillator Duty Cycle Maxdty(%)
RH5RH302B
–20
0
20
40
Temperature Topt(˚C)
60
80
60
80
100
IOUT=10mA
VIN=3V
L=28µH
90
80
70
60
50
–40
–20
0
20
40
Temperature Topt(˚C)
60
80
15) VLX Voltage Limit vs. Temperature
RH5RH501A
VLX Voltage Limit VLXlim(V)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
–40
–20
0
20
40
Temperature Topt(˚C)
16) EXT “H” Output Current vs. Temperature
17) EXT “L” Output Current vs. Temperature
RH5RH501A
20
EXT "L" Output Current IEXTL(mA)
EXT "H" Output Current IEXTH(mA)
RH5RH501A
10
8
6
4
2
0
–40
–20
20
40
0
Temperature Topt(˚C)
60
80
10
8
6
4
2
0
–40
–20
0
20
40
Temperature Topt(˚C)
60
80
RH5RH
18) Load Transient Response
RH5RH301A IOUT=1mA-30mA
4.5
210
6.5
210
4.0
180
6.0
180
150
3.0
120
2.5
90
60
2.0
Output Current
30
1.0
0
20
40
60
Time t(ms)
Output Voltage
5.5
150
5.0
120
4.5
90
60
4.0
Output Current
3.5
0
80
240
30
3.0
0
20
40
60
Time t(ms)
RH5RH502B
RH5RH302B IOUT=1mA-30mA
0
80
4.5
210
6.5
210
4.0
180
6.0
180
Output Voltage
3.5
150
3.0
120
2.5
90
2.0
Output Current
1.5
1.0
0
60
30
20
40
60
Time t(ms)
0
80
Output Voltage VOUT (V)
7.0
5.0
Output Current IOUT(mA)
240
IOUT=1mA-30mA
VIN=3V
L=28µH
240
VIN=2V
L=28µH
Output Voltage
5.5
150
5.0
120
4.5
90
4.0
Output Current
3.5
60
30
3.0
0
20
60
40
Time t(ms)
Output Current IOUT(mA)
Output Voltage
3.5
Output Voltage VOUT (V)
7.0
1.5
Output Voltage VOUT (V)
VIN=3V
L=120µH
240
Output Current IOUT(mA)
Output Voltage VOUT (V)
5.0
RH5RH501A IOUT=1mA-30mA
Output Current IOUT(mA)
VIN=2V
L=120µH
0
80
21
RH5RH
19) Distribution of Output Voltage
Output Voltage VOUT (V)
RH5RH501A
5.18~5.20
5.16~5.18
5.14~5.16
5.12~5.14
5.10~5.12
5.08~5.10
5.06~5.08
5.04~5.06
5.02~5.04
5.00~5.02
4.98~5.00
4.96~4.98
4.94~4.96
4.92~4.94
4.90~4.92
4.88~4.90
4.86~4.88
4.84~4.86
4.82~4.84
4.80~4.82
0
5
10
15
20
Distribution (%)
25
30
35
20) Distribution of Oscillator Frequency
Oscillator Frequency fosc (kHz)
RH5RH501A
59~60
58~59
57~58
56~57
55~56
54~55
53~54
52~53
51~52
50~51
49~50
48~49
47~48
46~47
45~46
44~45
43~44
42~43
41~42
40~41
0
22
5
10
15
Distribution (%)
20
25
RH5RH
TYPICAL APPLICATIONS
• RH5RH××1A
Diode
Inductor
VOUT
Lx
OUT
Vss
+
VIN
Capacitor
Components Inductor (L)
: 120µH (Sumida Electric Co., Ltd.)
Diode (D)
: MA721 (Matsushita Electronics Corporation, Schottky Type)
Capacitor (CL)
: 22µF (Tantalum Type)
FIG. 1
• RH5RH××2B
Inductor
Diode
VOUT
Cb
OUT
EXT
Vss
VIN
Tr
Components Inductor (L)
Rb
+
Capacitor
: 28µH (Troidal Core)
Diode (D)
: HRP22 (Hitachi, Schottky Type)
Capacitor (CL)
: 100µF (Tantalum Type)
Transistor (Tr)
: 2SD1628G
Base Resistor (Rb)
: 300Ω
Base Capacitor (Cb) : 0.01µF
FIG. 2
23
RH5RH
• RH5RH ×× 3B
Diode
Inductor
VOUT
Lx
NC
OUT
EXT
CE
Vss
+
VIN
Capacitor
Components Inductor (L)
: 120µH (Sumida Electric Co., Ltd.)
Diode (D)
: MA721 (Matsushita Electronics Corporation, Schottky Type)
Capacitor (CL)
: 22µF (Tantalum Type)
FIG. 3
Inductor
Diode
Cb
NC
Lx
VOUT
OUT
EXT
CE Vss
VIN
Tr
Components Inductor (L)
Rb
Capacitor
: 28µH (Troidal Core)
Diode (D)
: HRP22 (Hitachi, Schottky Type)
Capacitor (CL)
: 100µF (Tantalum Type)
Transistor (Tr)
: 2SD1628G
Base Resistor (Rb)
: 300Ω
Base Capacitor (Cb) : 0.01µF
FIG. 4
24
+
RH5RH
• CE pin Drive Circuit
Diode
Inductor
RH5RH××3B
Lx
NC
VOUT
OUT
EXT
CE Vss
Pull-up
resistor
+
VIN
Capacitor
CE
Tr
FIG. 5
25
RH5RH
APPLICATION CIRCUITS
• 12V Step-up Circuit
Inductor
Diode
VOUT
RH5RH502B
Cb
ZD:6.8V
+
OUT
VIN
Capacitor
EXT
Vss
RZD
Rb
Tr
Starter Circuit
(Note) When the Output Current is small or the Output Voltage is unstable,use the Rzd for flowing the bias current through the Zener diode ZD.
FIG. 6
• Step-down Circuit
Inductor
VOUT
PNP Tr
Diode
Rb2
RH5RH××1A
VIN
OUT
Lx
Rb1
Vss
+
Capacitor
Starter Circuit
(Note) When the L X pin Voltage is over the rating at the time PNP Tr is OFF,use a RH5RH ×× 2B and drive the PNP Tr. by the external NPN Tr.
FIG. 7
26
RH5RH
• Step-up/Step-down Circuit with Flyback
Trance1:1
Diode
VOUT
RH5RH ××1A
OUT
Lx
VIN
+
Vss
Capacitor
Starter Circuit
(Note) Use a RH5RH ×× 2B,depend on the Output Current.
FIG. 8
*The Starter Circuit is necessary for all above circuits.
1.for Step-up Circuit.
Starter Circuit
VOUT side
VIN side
2.for Step-down and Step-up/Step-down Circuit.
VIN side
VOUT side
RST
Tr
Starter Circuit
ZDST
ZDst 2.5V≤/ZDst≤Designation of Output Voltage
Rst Input Bias Current of ZDst and Tr.
(several kΩ to several hundreds kΩ)
27
RH5RH
PACKAGE DIMENSIONS (Unit: mm)
• SOT-89
• SOT-89-5
4.5±0.1
4.5±0.1
1.5±0.1
0.4
1.6±0.2
1.5±0.1
1.6±0.2
0.4±0.1
0.42±0.1
0.4±0.1
ø1.0
1
0.9
MIN.
0.4±0.1
3
2
+0.5
–0.3
2.5±0.1
0.4
4.25MAX.
2.5±0.1
3
2
4.5
1
0.8
MIN.
ø1.0
4
5
0.4±0.1
0.42
±0.1
0.47
±0.1
1.5±0.1
1.5±0.1
0.42
±0.1
0.42
±0.1
0.47
±0.1
1.5±0.1
1.5±0.1
TAPING SPECIFICATIONS (Unit: mm)
4.0±0.1
4.7
5.65±0.05
2.0±0.05
12±0.3
+0.1
ø 1.5 –0
0.3±0.1
1.5±0.1
• SOT-89
5.0
8.0±0.1
2.5MAX.
T2
T1
User Direction of Feed.
4.0±0.1
+0.1
ø 1.5 –0
5.0
4.7
8.0±0.1
2.5MAX.
T2
T1
User Direction of Feed.
28
12±0.3
2.0±0.05
5.65±0.05
0.3±0.1
1.5±0.1
• SOT-89-5
0.42
±0.1
RH5RH
APPLICATION HINTS
When using these ICs, be sure to take care of the following points :
• Set external components as close as possible to the IC and minimize the connection between the components
and the IC. In particular, when an external component is connected to OUT Pin, make minimum connection
with the capacitor.
• Make sufficient grounding. A large current flows through Vss Pin by switching. When the impedance of the
Vss connection is high, the potential within the IC is varied by the switching current. This may result in
unstable operation of the IC.
• Use capacitor with a capacity of 10µF or more, and with good high frequency characteristics such as tanta-
lum capacitor. We recommend the use of a capacitor with a resistance to the voltage being at least three
times the output set voltage. This is because there may be the case where a spike-shaped high voltage is generated by the inductor when Lx transistor is turned OFF.
• Take the utmost care when choosing a inductor. Namely, choose such an inductor that has sufficiently small
d.c. resistance and large allowable current, and hardly reaches magnetic saturation. When the inductance
value of the inductor is small, there may be the case where ILX exceeds the absolute maximum ratings at the
maximum load. Use an inductor with an appropriate inductance.
• Use a diode of a Schottky type with high switching speed, and also take care of the rated current.
• These ICs are provided with a soft-start circuit. However, there may be the case where the overshoot of the
out put voltage takes place depending upon the peripheral circuits employed and the input/output conditions. In particular, when the input voltage is increased slowly, the occurrence of the overshoot of the output
voltage becomes conspicuous. Therefore in the case where the overshoot becomes a problem, take a countermeasure against this problem, for example, by clamping the output (OUT Pin) by use of a Zener diode.
• The transient response characteristics corresponding to the variations in the input and output are set so as
to be slightly delayed by an internal phase compensation circuit in order to prevent the oscillation. because
of such setting of the transient response characteristics, take care of the occurrence of the overshoot and/or
undershoot of the output voltage.
• The internal phase compensation circuit is designed with the avoidance of the problem of the occurrence of
the oscillation fully taken into consideration. However, there may be the case the oscillation takes place
depending upon the conditions for the attachment of external components. In particular, take the utmost
care when an inductor with a large inductance is used.
The performance of power source circuits using these ICs largely depends upon the peripheral circuits. Take the utmost care in the
selection of the peripheral circuits. In particular, design the peripheral circuits in such a manner that the values such as voltage, current
and power of each component, PCB patterns and the IC do not exceed their respective rated values.
29
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