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PWM STEP-UP DC/DC CONVERTER
RH5RHxx1A/xx2B/xx3B SERIES
APPLICATION MANUAL
NO.EA-023-0006
PWM STEP-UP DC/DC CONVERTER
RH5RH xx1A/xx2B/xx3B SERIES
OUTLINE
The RH5RHxx1A/x x2B/xx3B Series are PWM Step-up DC/DC converter ICs by CMOS process. The RH5RHx x1A 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 RH5RHx x1A IC with only three external components, that is, an inductor, a diode and a capacitor. These RH5RHxx 1A/x x2B/xx3B ICs can achieve ultra-low supply current (no load) -TYP. 15A -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. 2A 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 RH5RHxx1A/xx2B/xx3B 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 RH5RHxx2B/xx3B Series ICs use the same chip as that employed in the RH5RHxx1A 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 RH5RHxx2B/xx3B Series ICs are recommendable to the user who need a current as large as several tens mA to several hundreds mA. The RH5RHxx3B IC also includes an internal chip enable circuit so that it is possible to set the standby supply current at MAX. 0.5A. These RH5RHxx1A/xx2B/xx3B 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 (RH5RHxx1A) * Low Supply Current ...........................................TYP. 15A (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. 500s * Small Packages ...................................................SOT-89 (RH5RHxx1A, RH5RHxx2B),
SOT-89-5 (RH5RHxx3B)
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
Lx Vss LxSW PWM control EXT OSC Chip Enable - + Error Amp. VLX limiter Buffer Slow start Phase Comp. Vref OUT
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 RH5RHxx1A and RH5RHxx3B EXT Pin .........only for RH5RHxx2B and RH5RHxx3B CE Pin ...........only for RH5RHxx3B
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 : RH5RHxxxx - xx Part Number ab 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. 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) Designation of Taping Type : Ex. SOT-89 : T1, T2 SOT-89-5 : T1, T2 (refer to Taping Specifications) "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 RH5RH502B-T1.
2
RH5RH
PIN CONFIGURATION
* SOT-89 * SOT-89-5
5
4
(mark side)
(mark side)
1
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
RH5RH
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
(Note 2) Applicable to RH5RHxx2B and RH5RHxx3B.
V V V V mA mA mW C C Note1 Note2 Note3 Note1 Note2
(Note 1) Applicable to RH5RHxx1A and RH5RHxx3B. (Note 3) Applicable to RH5RHxx3B.
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
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=3.0V
Note
VOUT VIN Vstart Vhold IDD1
Output Voltage Input Voltage Start-up Voltage Hold-on Voltage Supply Current 1 IOUT=1mA,VIN : 02V IOUT=1mA,VIN : 20V To be measured at OUT Pin (excluding Switching Current) To be measured at OUT Pin
2.925
3.000
3.075 8
V V V V
0.8 0.7 15
0.9
25
A
IDD2
Supply Current 2
(excluding Switching Current) VIN=3.5V
2
5
A
ILX ILXleak fosc Maxdty
Lx Switching Current Lx Leakage Current Oscillator Frequency Oscillator Maximum Duty Cycle Efficiency Soft-Start Time VLX Voltage Limit
VLX=0.4V VLX=6V,VIN=3.5V
60 0.5 40 50 80 85 2.0 60 90
mA A kHz % % ms Note1
on (VLX "L" ) side
70 70
tstart
VLXlim
Time required for the rising of VOUT up to 3V. Lx Switch ON
0.5
0.65
0.8
1.0
V
Note2
Unless otherwise provided, VIN=1.8V, VSS=0V, IOUT=10mA, Topt=25C, 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 200s 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
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=5.0V
Note
VOUT VIN Vstart Vhold IDD1
Output Voltage Input Voltage Start-up Voltage Hold-on Voltage Supply Current 1 Iout=1mA,Vin:02V Iout=1mA,Vin:20V To be measured at OUT Pin (excluding Switching Current) To be measured at OUT Pin
4.875
5.000
5.125 8
V V V V
0.8 0.7 30
0.9
45
A
IDD2
Supply Current 2
(excluding Switching Current) VIN=5.5V
2
5
A
ILX ILXleak fosc Maxdty
Lx Switching Current Lx Leakage Current Oscillator Frequency Oscillator Maximum Duty Cycle Efficiency Soft-Start Time
VLX=0.4V VLX=6V,VIN=5.5V
80 0.5 40 50 80 85 2.0 60 90
mA A kHz % % ms Note1
on (VLX "L" ) side
70 70
tstart
VLXlim
Time required for the rising of VOUT up to 5V.
0.5
VLX Voltage Limit
Lx Switch ON
0.65
0.8
1.0
V
Note2
Unless otherwise provided, VIN=3V, Vss=0V, IOUT=10mA, Topt=25C, 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 200s 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
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=3.0V
Note
VOUT VIN Vstart IDD1 IDD2 IEXTH IEXTL fosc Maxdty
Output Voltage Input Voltage Oscillator Start-up Voltage Supply Current 1 Supply Current 2 EXT "H" Output Current EXT "L" Output Current Oscillator Frequency Oscillator Maximum Duty Cycle VEXT "H" side Time required for the rising of VOUT up to 3V EXT no load,VOUT :02V EXT no load,VOUT=2.88V EXT 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 80 100 120
kHz
70
80
90
%
tstart
Soft-Start Time
0.5
2.0
ms
Note1
Unless otherwise provided, VIN=1.8V, Vss=0V, IOUT=10mA, Topt=25C, and use External Circuit of Typical Application (FIG. 2). * RH5RH502B
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=5.0V
Note
VOUT VIN Vstart IDD1 IDD2 IEXTH IEXTL fosc Maxdty
Output Voltage Input Voltage Oscillator Start-up Voltage Supply Current 1 Supply Current 2 EXT "H" Output Current EXT "L" Output Current Oscillator Frequency Oscillator Maximum Duty Cycle VEXT "H" side Time required for the rising of VOUT up to 5V EXT no load,VOUT :02V EXT no load,VOUT=4.8V EXT 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 80 100 120
kHz
70
80
90
%
tstart
Soft-Start Time
0.5
2.0
ms
Note1
Unless otherwise provided, VIN=3V, Vss=0V, IOUT=10mA, Topt=25C and use External Circuit of Typical Application (FIG. 2).
(Note 1) refer to page 5 (Note 1)
7
RH5RH
* RH5RH303B
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=3.0V
Note
VOUT VIN Vstart Vhold IDD1 IDD2 ILX ILXleak IEXTH IEXTL VCEH1 VCEL1 VCEH2 VCEL2 ICEH ICEL fosc Maxdty
Output Voltage Input Voltage Start-up Voltage Hold-on Voltage Efficiency Supply Current 1 Supply 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 Oscillator Frequency Oscillator Maximum Duty Cycle on (VLX "L" )side To be measured at OUT pin To be measured at OUT pin 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 85 30 2 60
0.9
% 50 5 A A mA 0.5 -1.5 A mA mA V 0.4 V V 0.1 0.5 V A A
1.5 VOUT-0.4
VOUT-0.1
-0.5 80 70 100 80 120 90
kHz %
tstart
VLXlim
Soft-Start Time VLX Voltage Limit
Time required for the rising of VOUT up to 3V. Lx Switch ON
0.5 0.65
2.0 0.8 1.0
ms V
Note1 Note2
Unless otherwise provided, VIN=1.8V, VSS=0V, IOUT=10mA, Topt=25C, 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 200s 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
Symbol Item Conditions MIN. TYP. MAX. Unit
VOUT=5.0V
Note
VOUT VIN Vstart Vhold IDD1 IDD2 ILX ILXleak IEXTH IEXTL VCEH1 VCEL1 VCEH2 VCEL2 ICEH ICEL fosc Maxdty
Output Voltage Input Voltage Start-up Voltage Hold-on Voltage Efficiency Supply Current 1 Supply 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 Oscillator Frequency Oscillator Maximum Duty Cycle on (VLX "L" )side To be measured at OUT pin To be measured at OUT pin 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 60 2 80
0.9
% 90 5 A A mA 0.5 -2.0 A mA mA V 0.4 V V 0.1 0.5 V A A
2.0 VOUT-0.4
VOUT-0.1
-0.5 80 70 100 80 120 90
kHz %
tstart
VLXlim
Soft-Start Time VLX Voltage Limit
Time required for the rising of VOUT up to 5V. Lx Switch ON
0.5 0.65
2.0 0.8 1.0
ms V
Note1 Note2
Unless otherwise provided, VIN=3V, VSS=0V, IOUT=10mA, Topt=25C, 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 200s 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 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 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 topentoff 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, topen0). 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* 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= 0 VIN * IL (t) dt = 0 (VIN2 * t/L) dt =VIN2 * ton2/(2 * L) ................................................................................................. Equation 3
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 * IL (t) dt = 0 ((VOUT-VIN) * t/L)dt Thus, POFF= 0
=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 RH5RH301A
3.1 Output Voltage VOUT(V) 3.0 2.9 2.8 2.7 1.5V 2.6 VIN =1.0V 2.5 0 20 40 Output Current IOUT(mA) 60 2.5 0 10 40 20 30 Output Current IOUT(mA) 50 60 2.0V L=120H Output Voltage VOUT(V)
RH5RH301A
3.1 3.0 2.9 2.8 2.7 1.5V 2.6 VIN=1.0V
L= 270H
2.0V
RH5RH501A
5.2 Output Voltage VOUT(V) 5.0 4.8 4.6 2.0V 4.4 4.2 4.0 0 VIN= 1.0V 50 100 Output Current IOUT(mA) 3.0V
L=120H
RH5RH501A
5.2 Output Voltage VOUT(V) 5.0
L=270H
4.0V 4.8 4.6 4.4 4.2 VIN=1.0V 4.0 0 50 100 Output Current IOUT(mA) 150 3.0V 2.0V
4.0V
150
RH5RH302B
3.1 Output Voltage VOUT(V) L=28H 5.2
RH5RH502B
L=28H 3.0V Output Voltage VOUT(V) 4.0V 2.0V
3.0
1.5V
2.0V
2.5V
5.0
4.8
2.9 VIN=0.9V 2.8 0 200 400 Output Current IOUT(mA) 600
4.6 VIN=1.5V 500 Output Current I OUT(mA) 1000
4.4 0
13
RH5RH
2) Efficiency vs. Output Current RH5RH301A
90 80 Efficiency (%) 2.0V 70 1.5V 60 50 40 VIN=1.0V L=120H 100 90 Efficiency (%) 80 70 60 VIN=1.0V 50 0 10 20 Output Current IOUT(mA) 30 40 0 10 30 20 Output Current IOUT(mA) 40 1.5V 2.0V
RH5RH301A
L=270H
RH5RH501A
100 90 Efficiency (%) 80 3.0V 70 2.0V 60 50 40 0 50 100 Output Current IOUT(mA) VIN=1.0V
L=120H
RH5RH501A
100 90
L=270H
4.0V
Efficiency (%)
80 70 60 50 VIN= 1.0V 2.0V 3.0V
4.0V
150
40 0
50 100 Output Current IOUT(mA)
150
RH5RH302B
100 80 Efficiency (%)
L = 28H
RH5RH502B
100 80 Efficiency (%)
L=28H
60 40 20 0
2.0V 1.5V VIN=0.9V
2.5V
3.0V 60 40 VIN=1.5V 20 0 2.0V
4.0V
0
200 400 Output Current IOUT(mA)
600
0
500 Output Current IOUT(mA)
1000
14
RH5RH
3) Supply Curret (No Load) vs. Input Voltage RH5RH301A
70 60 Supply Current IIN (A) Supply Current IIN (A) 50 40 30 20 10 0 1.0 1.2 1.6 1.4 Input Voltage VIN(V) 1.8 2.0 L=120H
RH5RH301A
70 60 50 40 30 20 10 0 1.0 1.2 1.4 1.6 Input Voltage VIN(V)
L=270H
1.8
2.0
RH5RH501A
200 Supply Current IIN (A)
L=120H
RH5RH501A
200 Supply Current IIN (A)
L=270H
150 100
150 100
50 0 1
50
2 3 Input Voltage VIN(V)
4
0
1
2 3 Input Voltage VIN(V)
4
4) Output Current vs.Ripple Voltage RH5RH301A
Ripple Voltage Vr (mV p-p) 80 70 60 50 40 30 20 10 0 1 5 10 20 30 40 50 60 70 80 90 100 Output Current IOUT(mA) VIN=0.9V 2.0V 3.0V L=120H Ripple Voltage Vr (mV p-p)
RH5RH501A
100
L=120H
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
70 Ripple Voltage Vr (mV p-p) 60 50 40 30 20 10 0 1 10 20 30 40 50 60 Output Current IOUT(mA) VIN=0.9V 2.0V
L=270H Ripple Voltage Vr (mV p-p)
RH5RH501A
80 70 60 50 40 30 20 10 0 1 VIN=0.9V 10 2.0V 3.0V
L=270H
3.0V
4.0V
70
80
20 30 40 50 60 70 Output Current IOUT(mA)
80
90
RH5RH302B
70 Ripple Voltage Vr (mV p-p) 60 50 40 30 20 10 0 1 50 100 150 Output Current IOUT(mA) VIN=0.9V 2.0V
L=28H Ripple Voltage Vr (mV p-p)
RH5RH502B
120 100 80 60 40 VIN=0.9V 20 0 1 50 2.0V
L=28H
3.0V
3.0V
4.0V
200
100 150 200 Output Current IOUT(mA)
250
5) Start-up/Hold-on Voltage vs. Output Current (Topt=25C)
Start-up/Hold-on Voltage Vstart/Vhold (V) L=120H Start-up/Hold-on Voltage Vstart/Vhold (V)
RH5RH301A
1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 20 10 Output Current IOUT(mA) 30 Vhold Vstart
RH5RH501A
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 20 10 Output Current IOUT(mA) 30 Vhold Vstart L=120H
16
RH5RH
Start-up/Hold-on Voltage Vstart/Vhold (V)
Start-up/Hold-on Voltage Vstart/Vhold (V)
RH5RH302B
1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 20 40 60 80 Output Current IOUT(mA) 100 Vhold Vstart L=28H
RH5RH502B
1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 80 20 40 60 Output Current IOUT(mA) 100 Vhold Vstart L=28H
6) Output Voltage vs.Temperature RH5RH301A
3.2 Output Voltage VOUT (V) 3.1 3.0 2.9 2.8 2.7 -40 IOUT=10mA VIN=2V L=120H Output Voltage VOUT (V)
RH5RH501A
5.2 5.1 5.0 4.9 4.8 4.7 -40
IOUT=10mA VIN=3V L=120H
-20
0 20 40 60 Temperature Topt(C)
80
100
-20
0 20 40 60 Temperature Topt(C)
80
100
RH5RH302B
3.2 Output Voltage VOUT (V) 3.1 3.0 2.9 2.8 2.7 -40
IOUT=10mA VIN=2V L=28H Output Voltage VOUT (V)
RH5RH502B
5.2 5.1 5.0 4.9 4.8 4.7 -40
IOUT=10mA VIN=3V L=28H
-20
60 0 20 40 Temperature Topt(C)
80
100
-20
0 20 40 60 Temperature Topt(C)
80
100
17
RH5RH
7) Start-up Voltage vs. Temperature RH5RH501A
1.2 Start-up Voltage Vstart(V) 1.0 0.8 0.6 0.4 0.2 0 -40 -20 40 0 20 Temperature Topt(C) 60 80
8) Hold-on Voltage vs. Temperature RH5RH501A
1.0 Hold-on Voltage Vhold(V) 0.8 0.6 0.4 0.2 0 -40
-20
20 40 0 Temperature Topt(C)
60
80
9) Supply Current 1 vs.Temperature RH5RH501A
100 Supply Current 1 IDD1(A) 80 60 40 20 0 -40
10) Supply Current 2 vs.Temperature RH5RH501A
5 Supply Current 2 IDD2(A) 4 3 2 1 0 -40
-20
0 20 40 Temperature Topt(C)
60
80
-20
0 20 40 Temperature Topt(C)
60
80
11) Lx Switching Current vs.Temperature RH5RH501A
150 125 100 75 50 25 0 -40 -20 0 20 40 Temperature Topt(C) 60 80
12) Lx Leakage Current vs.Temperature RH5RH501A
Lx Leakage Current ILXleak (A) 1.0 0.8 0.6 0.4 0.2 0 -40
Lx Switching Current ILX (mA)
-20
0 20 40 Temperature Topt(C)
60
80
18
RH5RH
13) Oscillator Frequency vs. Temperature RH5RH301A
Oscillator Frequency fosc(kHz) 100 90 80 70 60 50 40 30 20 10 0 -40 IOUT=10mA VIN=2V L=120H Oscillator Frequency fosc(kHz)
RH5RH501A
100 90 80 70 60 50 40 30 20 10 0 -40
IOUT=10mA VIN=3V L=120H
-20
40 0 60 20 Temperature Topt(C)
80
100
-20
20 40 60 0 Temperature Topt(C)
80
100
RH5RH302B
Oscillator Frequency fosc(kHz) 140 120 100 80 60 40 20 0 -40 -20 0 20 40 60 Temperature Topt(C)
IOUT=10mA VIN=2V L=28H Oscillator Frequency fosc(kHz)
RH5RH502B
140 120 100 80 60 40 20 0 -40 -20 0 20 40 60 Temperature Topt(C)
IOUT=10mA VIN=3V L=28H
80
100
80
100
14) Oscillator Duty Cycle vs. Temperature RH5RH301A
Oscillator Duty Cycle Maxdty(%) 100 90 80 70 60 50 -40 IOUT=10mA VIN=2V L=120H Oscillator Duty Cycle Maxdty(%)
RH5RH501A
100 90 80 70 60 50 -40
IOUT=10mA VIN=3V L=120H
-20
0 20 40 Temperature Topt(C)
60
80
-20
0 20 40 Temperature Topt(C)
60
80
19
RH5RH
RH5RH302B
Oscillator Duty Cycle Maxdty(%) 100 90 80 70 60 50 -40
IOUT=10mA VIN=2V L=28H Oscillator Duty Cycle Maxdty(%)
RH5RH502B
100 90 80 70 60 50 -40
IOUT=10mA VIN=3V L=28H
-20
0 20 40 Temperature Topt(C)
60
80
-20
0 20 40 Temperature Topt(C)
60
80
15) VLX Voltage Limit vs. Temperature RH5RH501A
1.2 VLX Voltage Limit VLXlim(V) 1.0 0.8 0.6 0.4 0.2 0.0 -40 80
-20
0 20 40 Temperature Topt(C)
60
16) EXT "H" Output Current vs. Temperature RH5RH501A
EXT "H" Output Current IEXTH(mA)
17) EXT "L" Output Current vs. Temperature RH5RH501A
EXT "L" Output Current IEXTL(mA) 10 8 6 4 2 0 -40
10 8 6 4 2 0 -40
-20
20 40 0 Temperature Topt(C)
60
80
-20
0 20 40 Temperature Topt(C)
60
80
20
RH5RH
18) Load Transient Response RH5RH301A IOUT=1mA-30mA
5.0 4.5 Output Voltage VOUT (V) 4.0 3.5 3.0 2.5 2.0 Output Current 1.5 1.0 0 20 40 60 Time t(ms) 30 0 80 Output Voltage VIN=2V L=120H 240 210 Output Current IOUT(mA) Output Voltage VOUT (V) 180 150 120 90 60 7.0 6.5 6.0 5.5 5.0 4.5 4.0 Output Current 3.5 3.0 0 20 40 60 Time t(ms) 30 0 80 Output Voltage
RH5RH501A IOUT=1mA-30mA
VIN=3V L=120H 240 210 180 150 120 90 60 Output Current IOUT(mA) Output Current IOUT(mA)
RH5RH302B IOUT=1mA-30mA
5.0 4.5 Output Voltage VOUT (V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0 20 Output Current Output Voltage VIN=2V L=28H 240 210 Output Current IOUT(mA) Output Voltage VOUT (V) 180 150 120 90 60 30 40 60 Time t(ms) 0 80 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 0
RH5RH502B
IOUT=1mA-30mA VIN=3V L=28H 240 210 180
Output Voltage
150 120 90
Output Current
60 30
20
60 40 Time t(ms)
0 80
21
RH5RH
19) Distribution of Output Voltage
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 RH5RH501A
Output Voltage VOUT (V)
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 5 10 15 Distribution (%) 20 25
22
Oscillator Frequency fosc (kHz)
RH5RH
TYPICAL APPLICATIONS
* RH5RHxx1A
Diode Inductor VOUT Lx Vss VIN Capacitor OUT +
Components Inductor (L) Diode (D) Capacitor (CL)
: 120H (Sumida Electric Co., Ltd.) : MA721 (Matsushita Electronics Corporation, Schottky Type) : 22F (Tantalum Type) FIG. 1
* RH5RHxx2B
Inductor Diode
VOUT Cb EXT Vss VIN Tr Rb + Capacitor OUT
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. 2
23
RH5RH
* RH5RHxx3B
Diode Inductor VOUT Lx NC VIN Capacitor EXT CE Vss + OUT
Components Inductor (L) Diode (D) Capacitor (CL)
: 120H (Sumida Electric Co., Ltd.) : MA721 (Matsushita Electronics Corporation, Schottky Type) : 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
24
RH5RH
* CE pin Drive Circuit
Diode
Inductor
RH5RHxx3B VOUT Lx NC EXT CE Vss Pull-up resistor + Capacitor OUT
VIN
CE Tr
FIG. 5
25
RH5RH
APPLICATION CIRCUITS
* 12V Step-up Circuit
Inductor Diode VOUT
RH5RH502B 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 RH5RHxx1A 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 RH5RHxx2B 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 xx1A Lx VIN Vss + Capacitor OUT
Starter Circuit
(Note) Use a RH5RHxx2B,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
2.for Step-down and Step-up/Step-down Circuit. VIN side
VOUT side RST Tr
Starter Circuit ZDST
ZDst 2.5V/ZDstDesignation of Output Voltage Rst Input Bias Current of ZDst and Tr. (several k to several hundreds k)
27
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 10F 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 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.
28

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