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VFM STEP-UP DC/DC CONVERTER
RH5RIxx1B/xx2B/xx3B SERIES
APPLICATION MANUAL
NO.EA-025-0006
VFM STEP-UP DC/DC CONVERTER
RH5RI xx1B/xx2B/xx3B SERIES
OUTLINE
The RH5RIxx1B/xx2B/xx3B Series are VFM (Chopper) Step-up DC/DC converter ICs with ultra low supply current by CMOS process. The RH5RIxx1B IC consists of an oscillator, a VFM control circuit, a driver transistor (Lx switch), a reference voltage unit, an error amplifier, resistors for voltage detection, and an Lx switch protection circuit. A low ripple, high efficiency step-up DC/DC converter can be constructed of this RH5RIxx1B IC with only three external components, that is, an inductor, a diode and a capacitor. The RH5RIxx2B IC uses the same chip as that employed in the RH5RIxx1B IC and is provided with a drive pin (EXT) for an external transistor instead of an Lx pin, so that a power transistor with a low saturation voltage can be externally provided, whereby a large current can be caused to flow through the inductor and accordingly a large current can be obtained. Therefore, the RH5RIxx2B IC is recommendable to the user who need a current as large as several tens mA toseveral hundreds mA. The RH5RIxx3B IC also includes an internal chip enable circuit so that it is possible to set the standby supply current at MAX. 0.5A. These RH5RIxx1B/xx2B/xx3B ICs are suitable for use with battery-powered instruments with low noise and ultra low supply current.
FEATURES
* Small Number of External Components ..........Only an inductor, a diode and a capacitor (RH5RIxx1B) * Ultra Low Input Current ...................................TYP. 4A (RH5RI301B/303B at no load,with 1.5V input) * High Output Voltage Accuracy .........................2.5% * Low Ripple and Low Noise * Low Start-up Voltage (When the output current is 1mA) ......................MAX. 0.9V * High Efficiency ...................................................TYP.80% * Low Temperature-Drift Coefficient of Output Voltage ..........................TYP. 50 ppm/C * Small Packages ...................................................SOT-89 (RH5RIxx1B, RH5RIxx2B)
SOT-89-5 (RH5RIxx3B)
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 appliances which require higher cell voltage than that of batteries used in the appliances.
1
RH5RI
BLOCK DIAGRAM
VLX limiter LxSW Buffer
-
Lx
Vref OUT
Vss
VFM Control
+
OSC 100kHz EXT Chip Enable
Error Amp.
CE
(Note) Lx Pin............only for RH5RIxx1B and RH5RIxx3B EXT Pin.........only for RH5RIxx2B and RH5RIxx3B CE Pin...........only for RH5RIxx3B
SELECTION GUIDE
In RH5RI 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 : RH5RIxxxx - xx Part Number
} }
ab
}
c
Code
Contents
a
Setting Output Voltage (VOUT): Stepwise setting with a step of 0.1V in the range of 2.5V to 7.5V is possible. Designation of Driver: 1B: Internal Lx Tr. Driver (Oscillator Frequency 100kHz) 2B: External Tr. Driver (Oscillator Frequency 100kHz) 3B: Internal Tr./External Tr. (selectively available) (Oscillator Frequency 100kHz, with chip enable function) Designation of Taping type : Ex. SOT-89 : T1, T2 SOT-89-5 : T1, T2 (refer to Taping Specification) "T1" is prescribed as a standard.
b
c
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 RH5RI502B-T1.
2
RH5RI
PIN CONFIGURATION
* SOT-89 * SOT-89-5
5
4
(mark side)
(mark side)
1
xx1A/xx2B
2
3
1
2
3
PIN DESCRIPTION
Pin No.
xx1B
1 2 3 -- --
xx2B
1 2 -- 3 --
xx3B
5 2 4 3 1
Symbol
Description
VSS OUT Lx EXT CE
Ground Pin Step-up Output Pin, Power Supply (for device itself) Switching Pin (Nch Open Drain) External Tr. Drive Pin (CMOS Output) Chip Enable Pin (Active Low)
3
RH5RI
ABSOLUTE MAXIMUM RATINGS
Symbol Item Rating Unit
Vss=0V
Note
VOUT VLX VEXT VCE ILX IEXT PD Topt Tstg Tsolder
Output Pin Voltage Lx Pin Voltage EXT Pin Voltage CE Pin Voltage Lx Pin Output Current EXT Pin Current Power Dissipation Operating Temperature Range Storage Temperature Range Lead Temperature (Soldering)
+12 +12 -0.3 to VOUT+0.3 -0.3 to VOUT+0.3 250 50 500 -30 to +80 -55 to +125 260C,10s
V V V V mA mA mW C C Note1 Note2 Note3 Note1 Note2
(Note 1) Applicable to RH5RIxx1A and RH5RIxx3B. (Note 2) Applicable to RH5RIxx2B and RH5RIxx3B. (Note 3) Applicable to RH5RIxx3B.
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
RH5RI
ELECTRICAL CHARACTERISTICS
* RH5RI301B
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=3.0V
Note
VOUT VIN Vstart Vhold IIN1
Output Voltage Input Voltage Start-up Voltage Hold-on Voltage Input Current 1 IOUT=1mA,VIN:02V IOUT=1mA,VIN:20V To be measured at VIN at no load To be measured at VIN VIN=3.5V VLX=0.4V VLX=6V,VIN=3.5V
2.925
3.000
3.075 8
V V V V
0.8 0.7 4
0.9
8
A
IIN2 ILX ILXleak fosc Maxdty VLXlim
Input Current 2 Lx Switching Current Lx Leakage Current Maximum Oscillator Frequency Oscillator Duty Cycle Efficiency VLX Voltage Limit
2 60
5
A mA
0.5 80 100 75 80 0.8 1.0 120 85
A kHz % % V Note
on (VLX "L" ) side
65 70
Lx Switch On
0.65
Unless otherwise provided, VIN=1.8V, Vss=0V, IOUT=10mA, Topt=25C, and use External Circuit of Typical Application (FIG. 1).
(Note)
ILX is gradually increased by the external inductor 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 Lx Switch Protection Circuit. The time period from the time at which VLX reaches VLXlim to the time at which Lx Switch is turned OFF is about 3s.
5
RH5RI
* RH5RI501B Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=5.0V
Note
VOUT VIN Vstart Vhold IIN1
Output Voltage Input Voltage Start-up Voltage Hold-on Voltage Input Current 1 IOUT=1mA,VIN:0 2V IOUT=1mA,VIN:20V To be measured at VIN at no load
4.875
5.000
5.125 8
V V V V
0.8 0.7 6
0.9
12
A
IIN2 ILX ILXleak fosc Maxdty VLXlim
Input Current 2 Lx Switching Current Lx Leakage Current Maximum Oscillator Frequency Oscillator Duty Cycle Efficiency VLX Voltage Limit
To be measured at VIN VIN=5.5V VLX=0.4V VLX=6V,VIN=5.5V 80 on (VLX "L" ) side 65 70 Lx Switch On 0.65 80
2
5
A mA
0.5 100 75 80 0.8 1.0 120 85
A kHz % % V Note2
Unless otherwise provided, VIN=3V, Vss=0V, IOUT=10mA, Topt=25C, and use External Circuit of Typical Application (FIG. 1).
(Note)
ILX is gradually increased by the external inductor 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 Lx Switch Protection Circuit. The time period from the time at which VLX reaches VLXlim to the time at which Lx Switch is turned OFF is about 3s.
6
RH5RI
* RH5RI302B
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=3.0V
Note
VOUT VIN Vstart IDD1 IDD2 IEXTH IEXTL fosc
Output Voltage Input Voltage Oscillator Start-up Voltage Supply Current 1 Supply Current 2 EXT "H" Output Current EXT "L" Output Current Maximum Oscillator Frequency EXT at no load,VOUT:0 2V EXT at no load,VOUT=2.88V EXT at no load,VOUT=3.5V VEXT=VOUT-0.4V VEXT=0.4V
2.925
3.000
3.075 8
V V V A A mA mA
0.7 30 2
0.8 50 5 -1.5
1.5 80 100 75 120 85
kHz %
Maxdty
Oscillator Duty Cycle
VEXT "H" side
65
Unless otherwise provided, VIN=1.8V, Vss=0V, IOUT=10mA, Topt=25C, and use External Circuit of Typical Application (FIG. 2).
* RH5RI502B
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=5.0V
Note
VOUT VIN Vstart IDD1 IDD2 IEXTH IEXTL fosc
Output Voltage Input Voltage Oscillator Start-up Voltage Supply Current 1 Supply Current 2 EXT "H" Output Current EXT "L" Output Current Maximum Oscillator Frequency EXT at no load,VOUT:02V EXT at no load,VOUT=4.8V EXT at no load,VOUT=5.5V VEXT=VOUT-0.4V VEXT=0.4V
4.875
5.000
5.125 8
V V V A A mA mA
0.7 60 2
0.8 90 5 -2
2 80 100 75 120 85
kHz %
Maxdty
Oscillator Duty Cycle
VEXT "H" side
65
Unless otherwise provided, VIN=3V, Vss=0V, IOUT=10mA, Topt=25C, and use External Circuit of Typical Application (FIG. 2).
7
RH5RI
* RH5RI303B
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=3.0V
Note
VOUT VIN Vstart Vhold IIN1
Output Voltage Input Voltage Start-up Voltage Hold-on Voltage Efficiency Input Current 1 To be measured at VIN at no load To be measured at VIN VIN=3.5V VLX=0.4V VLX=6V,VIN=3.5V VEXT=VOUT-0.4V VEXT=0.4V VOUT1.5V VOUT1.5V 0.8VVOUT<1.5V 0.8VVOUT<1.5V CE=3V CE=0V IOUT=1mA,VIN:02V IOUT=1mA,VIN:20V
2.925
3.000
3.075 8
V V V V
0.8 0.7 70 80 4
0.9
% 8 A
IIN2 ILX ILXleak IEXTH IEXTL VCEH1 VCEL1 VCEH2 VCEL2 ICEH ICEL fosc Maxdty VLXlim
Input Current 2 Lx Switching Current Lx Leakage Current EXT "H" Output Current EXT "L" Output Current CE "H" Level 1 CE "L" Level 1 CE "H" Level 2 CE "L" Level 2 CE "H" Input Current CE "L" Input Current Maximum Oscillator Frequency Oscillator Duty Cycle VLX Voltage Limit
2 60
5
A mA
0.5 -1.5 1.5 VOUT-0.4 0.4 VOUT-0.1 0.1 0.5 -0.5 80 100 75 0.8 120 85 1.0
A mA mA V V V V A A kHz % V Note
on (VLX "L" )side Lx Switch on
65 0.65
Unless otherwise provided, VIN=1.8V, VSS=0V, IOUT=10mA, Topt=25C, and use External Circuit of Typical Application (FIG. 3).
(Note) ILX is gradually increased by the external inductor 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 Lx Switch Protection Circuit. The time period from the time at which VLX reaches VLXlim to the time at which Lx Switch is turned OFF is about 3s.
8
RH5RI
* RH5RI503B
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=5.0V
Note
VOUT VIN Vstart Vhold IIN1
Output Voltage Input Voltage Start-up Voltage Hold-on Voltage Efficiency Input Current 1 To be measured at VIN at no load To be measured at VIN VIN=5.5V VLX=0.4V VLX=6V,VIN=5.5V VEXT=VOUT-0.4V VEXT=0.4V VOUT1.5V VOUT1.5V 0.8VVOUT<1.5V 0.8VVOUT<1.5V CE=5V CE=0V IOUT=1mA,VIN:02V IOUT=1mA,VIN:20V
4.875
5.000
5.125 8
V V V V
0.8 0.7 70 85 6
0.9
% 12 A
IIN2 ILX ILXleak IEXTH IEXTL VCEH1 VCEL1 VCEH2 VCEL2 ICEH ICEL fosc Maxdty VLXlim
Input Current 2 Lx Switching Current Lx Leakage Current EXT "H" Output Current EXT "L" Output Current CE "H" Level 1 CE "L" Level 1 CE "H" Level 2 CE "L" Level 2 CE "H" Input Current CE "L" Input Current Maximum Oscillator Frequency Oscillator Duty Cycle VLX Voltage Limit
2 80
5
A mA
0.5 -2.0 2.0 VOUT-0.4 0.4 VOUT-0.1 0.1 0.5 -0.5 80 100 75 0.8 120 85 1.0
A mA mA V V V V A A kHz % V Note
on (VLX "L" )side Lx Switch on
65 0.65
Unless otherwise provided, VIN=3V, VSS=0V, IOUT=10mA, Topt=25C and use External Circuit of Typical Application (FIG. 3).
(Note) ILX is gradually increased by the external inductor 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 Lx Switch Protection Circuit. The time period from the time at which VLX reaches VLXlim to the time at which Lx Switch is turned OFF is about 3s.
9
RH5RI
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 i1 Lx Tr CL SD IOUT VOUT ton T=1/fosc toff ILmin ILmax topen
t
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 protection 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 IL reaches ILmin (=0) after a time period of topen, so that SD is turned OFF. In the case of VFM control system, the output voltage is maintained constant by controlling the oscillator frequency (fosc) with the on-time period (ton) being maintained constant. 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 topentoff In Equation 1,VIN * ton/L and (VOUT-VIN) * topen/L are respectively the change in the current at ON, and the change in the current at OFF. In the VFM system, 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).
10
RH5RI
SELECTION OF PERIPHERAL COMPONENTS
When LxTr is on, the energy PON charged in the inductor is provided by Equation 2 as follows :
ton PON=0 (VIN * IL (t)) dt=0 (VIN2 * t/L) dt =VIN2 * ton2/(2 * L).................................................................................................... Equation 2
ton
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.
topen topen (VIN * (VOUT-VIN) * t/L)dt Thus, POFF =0 (VIN * IL (t)) dt=0 2 =VIN * (VOUT-VIN) * topen /(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 3 Input power PIN is (PON+POFF)/T. When this is converted in its entirely to the output. PIN=(PON+POFF)/T=VOUT * IOUT=POUT .........................................................................Equation 4 Equation 5 can be obtained as follows by solving Equation 4 for IOUT by substituting Equation 2 and 3 into Equation 4 : IOUT=VIN2 * ton2/(2 * L * T * (VOUT-VIN) =VIN2 * maxdty2/(20000 * fosc * L * (VOUT-VIN)) ...................................................Equation 5 The peak current which flows through L * LxTr * SD is ILmax=VIN * ton/L .......................................................................................................... Equation 6 Therefore, it is necessary that the setting of the input/output conditions and the selection of peripheral components be made with ILmax taken into consideration.
HINTS
The above explanation is directed to the calculation in an ideal case where it is supposed that there is no energy loss 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 reduction caused by LxSW when IL is large or VIN is small. 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. When ILX and VLX exceed their respective ratings, use RH5RIxx2B and RH5RIxx3B ICs with the attachment of an external transistor with a low saturation voltage thereto.
11
RH5RI
TYPICAL CHARACTERISTICS
1) Output Voltage vs. Output Current RH5RI351B
4.0 Output Voltage VOUT(V) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 20 60 40 80 Output Current IOUT(mA) 100 3.0V 1.0V VIN=0.9V 2.0V L=82H Output Voltage VOUT(V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 20 40 60 80 Output Current IOUT(mA) 100 VIN=0.9V 1.0V 3.0V 2.0V
RH5RI351B
L=120H
RH5RI501B
6 Output Voltage VOUT(V) 5 4 VIN=0.9V 3 2 1 0 0 20 1.5V 2.0V 3.0V
L=82H Output Voltage VOUT(V)
RH5RI501B
6 5 4 3 VIN=0.9V 2 1 0 0 20 1.5V 2.0V
L=120H 4.0V 3.0V
4.0V
40 80 60 Output Current IOUT(mA)
100
80 40 60 Output Current IOUT(mA)
100
RH5RI352B
4.0 Output Voltage VOUT(V) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 400 200 Output Current IOUT(mA) 600 1.0V VIN=0.9V 2.0V L=28H 3.0V Output Voltage VOUT(V) 6 5 4 3 2 1 0 0 VIN=0.9V
RH5RI502B
L=28H
1.5V
2.0V
3.0V
4.0V
200 400 Output Current IOUT(mA)
600
12
RH5RI
2) Efficiency vs. Output Current RH5RI351B
100 90 80 70 1.0V 60 VIN=0.9V 50 40 30 20 10 0 20 0 L=82H
RH5RI351B
L=120H 100 90 80 3.0V 70 2.0V 1.0V 60 50 VIN=0.9V 40 30 20 10 0 60 80 20 40 0 100 Output Current IOUT(mA)
3.0V 2.0V Efficiency (%) 100
Efficiency (%)
60 40 80 Output Current IOUT(mA)
RH5RI501B
100 90 80 4.0V 70 3.0V 60 1.5V 2.0V 50 VIN=0.9V 40 30 20 10 0 60 100 40 0 20 80 Output Current I OUT(mA) L=82H
RH5RI501B
L=120H 100 4.0V 90 80 3.0V 70 1.5V 60 VIN=0.9V 2.0V 50 40 30 20 10 0 40 0 20 80 100 60 Output Current IOUT(mA)
Efficiency (%)
RH5RI352B
100 90 80 70 60 50 40 30 20 10 0 0
Efficiency (%)
L=28H
1.0V VIN=0.9V
2.0V
3.0V
400 200 Output Current I OUT(mA)
600
L=28H 100 90 80 4.0V 70 3.0V 2.0V 60 1.5V 50 40 VIN=0.9V 30 20 10 0 600 200 0 400 Output Current IOUT(mA)
RH5RI502B
Efficiency (%)
Efficiency (%)
13
RH5RI
3) Output Current vs.Ripple Voltage RH5RI351A
Ripple Voltage Vr (mV p-p) 120 100 80 3.0V 60 40 20 0 0 VIN=0.9V 20 40 60 80 Output Current IOUT(mA) 100 0 0 40 20 60 80 Output Current I OUT(mA) 100 1.5V 2.0V L=82H Ripple Voltage Vr (mV p-p) 120 100 80 60 1.5V 40 20 VIN=0.9V 2.0V 3.0V
RH5RI351B
L=120H
RH5RI501B
Ripple Voltage Vr (mV p-p) 120 100 80 3.0V 60 2.0V 40 20 VIN=0.9V 0 0
L=82H Ripple Voltage Vr (mV p-p)
RH5RI501B
140 120 100 80 60 40 20 0 0 VIN=0.9V 2.0V 3.0V
L=120H
4.0V
4.0V
40 20 60 80 Output Current IOUT(mA)
100
20 40 60 80 Output Current IOUT(mA)
100
RH5RI352B
200 180 160 140 120 100 80 60 40 20 0 0 Ripple Voltage Vr (mV p-p) 2.0V
L=28H 250 Ripple Voltage Vr (mV p-p)
RH5RI502B
3.0V 200 2.0V 150 100 50 VIN=0.9V 0 0 200 400 Output Current IOUT(mA)
L=28H 4.0V
3.0V 1.5V
VIN=0.9V 100 200 300 Output Current IOUT(mA) 400
600
14
RH5RI
4) Start-up/Hold-on Voltage vs. Output Current
Start-up/Hold-on Voltage Vstart/Vhold (V) L=82H Start-up/Hold-on Voltage Vstart/Vhold (V)
RH5RI351B
1.2 1.0 0.8 0.6 Vhold 0.4 0.2 0 0 5 10 Output Current IOUT(mA) 15 Vstart
RH5RI501B
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 10 5 Output Current I OUT(mA) Vhold Vstart
L=82H
15
Start-up/Hold-on Voltage Vstart/Vhold (V)
2.5 2.0 1.5 Vstart 1.0 0.5 0 0 100 150 50 Output Current IOUT(mA) Vhold
L=28H
Start-up/Hold-on Voltage Vstart/Vhold (V)
RH5RI352B
RH5RI502B
2.5 2.0 1.5 1.0 Vhold 0.5 0 0 150 100 50 Output Current IOUT(mA) 200 Vstart L=28H
200
5) Output Voltage vs. Temperature RH5RI501B
5.20 Output Voltage VOUT(V) 5.15 5.10 5.05 5.00 4.95 4.90 4.85 4.80 -40 -20 20 0 40 Temperature Topt(C) 60 80
6) Start-up Voltage vs. Temperature RH5RI501B
1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -40 Start-up Voltage Vstart(V)
-20
20 0 40 Temperature Topt(C)
60
80
15
RH5RI
7) Hold-on Voltage vs. Temperature RH5RI501B
0.8 Hold-on Voltage Vhold (V)
8) Supply Current 1 vs.Temperature RH5RI502B
60 Supply Current IDD1( A) 50 40 30 20 10 0 -40 -20 0 20 40 Temperature Topt(C) 60 80
0.7 0.6 0.5 0.4 0.3 0.2 -40 -20 0 20 40 Temperature Topt(C) 60 80
9) Input Current 2 vs.Temperature RH5RI501B
1.8 Input Current IIN2( A) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 -40
10) Lx Switching Current vs.Temperature RH5RI501B
Lx Switching Current ILX (mA) 200 180 160 140 120 100 80 60 40 20 0 -40
-20
0 20 40 Temperature Topt(C)
60
80
-20
0 20 40 Temperature Topt(C)
60
80
11) Lx Leakage Current vs.Temperature RH5RI501B
Lx Leakage Current ILXleak( A) 0.30 0.25 0.20 0.15 0.10 0.05 0 -40 -20 20 0 40 Temperature Topt(C) 60 80
12) Maximum Oscillator Frequency vs.Temperature
Maximum Oscillator Frequency fosc (kHz)
RH5RI501B
160 140 120 100 80 60 40 20 0 -40 -20 40 0 20 Temperature Topt(C) 60 80
16
RH5RI
13) Oscillatar Duty Cycle vs. Temperature RH5RI501B
Oscillator Duty Cycle Maxdty(%) 100
14) Vlx Voltage Limit vs. Temperature RH5RI501B
1.00 VLX Voltage Limit VLXlim(V) 0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 -40
90 80 70 60 50 -40
-20
20 0 40 Temperature Topt(C)
60
80
-20
20 0 40 Temperature Topt(C)
60
80
15) Output Current vs. Temperature
EXT "H" Output Current IEXTH(mA)
16) Output Current vs. Temperature
EXT "L" Output Current IEXTL(mA)
RH5RI502B
5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -40 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -40
RH5RI502B
-20
20 0 40 Temperature Topt(C)
60
80
-20
0 20 40 Temperature Topt(C)
60
80
17
RH5RI
TYPICAL APPLICATIONS
* RH5RIxx1B
Diode Inductor VOUT Lx Vss VIN Capacitor OUT +
Components Inductor (L) Diode (D)
: 82H (Sumida Electric Co., Ltd.) : MA721 (Matsushita Electronics Corporation, Schottky Type)
Capacitor (CL) : 22F (Tantalum Type) FIG. 1 * RH5RIxx2B
Inductor
Diode
VOUT Cb EXT Vss VIN Tr Rb + Capacitor OUT
Components Inductor (L) Diode (D) Capacitor (CL) Transistor (Tr) Base Resistor (Rb) Base Capacitor (Cb)
: 28H (Troidal Core) : HRP22 (Hitachi, Schottky Type) : 100F (Tantalum Type) : 2SD1628G : 300 : 0.01F FIG. 2
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RH5RI
* RH5RIxx3B
Diode Inductor VOUT Lx NC VIN Capacitor EXT CE Vss + OUT
Components Inductor (L) Diode (D)
: 82H (Sumida Electric Co., Ltd.) : MA721 (Matsushita Electronics Corporation, Schottky Type)
Capacitor (CL) : 22F (Tantalum Type) FIG. 3
Inductor
Diode
Cb
NC
Lx EXT CE Vss
VOUT OUT + Capacitor
VIN Tr
Rb
Components Inductor (L) Diode (D) Capacitor (CL) Transistor (Tr) Base Resistor (Rb)
: 28H (Troidal Core) : HRP22 (Hitachi, Schottky Type) : 100F (Tantalum Type) : 2SD1628G : 300
Base Capacitor (Cb) : 0.01F FIG. 4
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RH5RI
* CE pin Drive Circuit
Diode
Inductor
RH5RI xx3B Lx NC EXT CE Vss Pull-up resistor + OUT
VOUT
VIN
Capacitor
CE Tr
FIG. 5
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RH5RI
APPLICATION CIRCUITS
* 12V Step-up Circuit
Inductor Diode VOUT
RH5RI502B Cb VIN EXT Vss Tr Rb OUT
ZD:6.8V + Capacitor RZD
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 PNP Tr Rb2 Diode RH5RI xx1B VIN Lx Rb1 Vss + Capacitor OUT VOUT
Starter Circuit
(Note) When the Lx pin Voltage is over the rating at the time PNP Tr is OFF,use a RH5RIxx2B and drive the PNP Tr. by the external NPN Tr.
FIG. 7
21
RH5RI
* Step-up/Step-down Circuit with Flyback
Trance1:1 Diode VOUT
RH5RI xx1B Lx VIN Vss + Capacitor OUT
Starter Circuit
(Note) Use a RH5RIxx2B,depend on the Output Current.
FIG. 8
*The Starter Circuit is necessary for all above circuits.
1.For Step-up Circuit.
Starter Circuit
VIN side
VOUT side
1.For Step-down and Step-up/Step-down Circuit.
VIN side RST Starter Circuit ZDST Tr
VOUT side
ZDst 2.5VZDSTDesignation of Output Voltage Rst Input Bias Current of ZDST and Tr. (several k to several hundreds k)
22
RH5RI
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 mayresult in unstable operation of the IC. * Use capacitor with a capacity of 10F or more, and with good high frequency characteristics such as tantalum capacitor. We recommend the use of a capacitor with an allowable voltage which is 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 an 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 (refer to Selectionof peripheral components). * Use a diode of a Schottky type with high switching speed, and also take care of the rated current (refer to Selection of peripheral components).
The performance of power source circuits using these ICs largely depends upon the peripheral components. Take the utmost care in the selection of the peripheral components. 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.
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