VFM STEP-UP DC/DC CONVERTER RH5RI××1B/××2B/××3B SERIES APPLICATION MANUAL NO.EA-025-0006 VFM STEP-UP DC/DC CONVERTER RH5RI ×× 1B/ ×× 2B/ ×× 3B SERIES OUTLINE The RH5RI ×× 1B/×× 2B/×× 3B Series are VFM (Chopper) Step-up DC/DC converter ICs with ultra low supply current by CMOS process. The RH5RI×× 1B 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 RH5RI×× 1B IC with only three external components, that is, an inductor, a diode and a capacitor. The RH5RI×× 2B IC uses the same chip as that employed in the RH5RI×× 1B 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 RH5RI×× 2B IC is recommendable to the user who need a current as large as several tens mA toseveral hundreds mA. The RH5RI×× 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 RH5RI×× 1B/×× 2B/×× 3B 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 (RH5RI ×× 1B) • Ultra Low Input Current ...................................TYP. 4µA (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 (RH5RI ×× 1B, RH5RI ×× 2B) SOT-89-5 (RH5RI ×× 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 appliances which require higher cell voltage than that of batteries used in the appliances. 1 RH5RI BLOCK DIAGRAM Vref VLX limiter Lx LxSW OUT Buffer – Vss VFM Control + OSC 100kHz EXT Error Amp. Chip Enable CE (Note) Lx Pin............only for RH5RI ×× 1B and RH5RI ×× 3B EXT Pin.........only for RH5RI ×× 2B and RH5RI×× 3B CE Pin...........only for RH5RI ×× 3B 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 : } } } RH5RI ×××× – ×× ← Part Number ↑ ↑ ↑ a b 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. b 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) c Designation of Taping type : Ex. SOT-89 : T1, T2 SOT-89-5 : T1, T2 (refer to Taping Specification) “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 RH5RI502B-T1. 2 RH5RI PIN CONFIGURATION • SOT-89 • SOT-89-5 5 (mark side) 1 2 ×× 1A/×× 2B 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 RH5RI 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 260˚C,10s (Note 1) Applicable to RH5RI ×× 1A and RH5RI ×× 3B. (Note 2) Applicable to RH5RI ×× 2B and RH5RI ×× 3B. (Note 3) Applicable to RH5RI ×× 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 RH5RI ELECTRICAL CHARACTERISTICS • RH5RI301B VOUT=3.0V Symbol VOUT VIN Item Conditions Output Voltage 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 IIN1 Input Current 1 IIN2 Input Current 2 ILX Lx Switching Current ILXleak Lx Leakage Current 0.7 To be measured at VIN at no load To be measured at VIN VIN=3.5V VLX=0.4V V 4 8 µA 2 5 µA 60 mA VLX=6V,VIN=3.5V Maximum Oscillator fosc 0.8 Note 0.5 µA 80 100 120 kHz 65 75 85 % 70 80 0.65 0.8 Frequency Maxdty η Oscillator Duty Cycle on (VLX “L” ) side Efficiency VLXlim VLX Voltage Limit Lx Switch On % 1.0 V Note Unless otherwise provided, VIN=1.8V, Vss=0V, IOUT=10mA, Topt=25˚C, 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 3µs. 5 RH5RI • RH5RI501B VOUT=5.0V Symbol VOUT VIN Item Conditions Output Voltage 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 IIN1 Input Current 1 0.8 0.7 To be measured at VIN at no load IIN2 Input Current 2 To be measured at VIN Note V 6 12 µA 2 5 µA VIN=5.5V ILX Lx Switching Current ILXleak Lx Leakage Current VLX=0.4V mA VLX=6V,VIN=5.5V Maximum Oscillator fosc 80 0.5 µA 80 100 120 kHz 65 75 85 % 70 80 0.65 0.8 Frequency Maxdty η Oscillator Duty Cycle on (VLX “L” ) side Efficiency VLXlim VLX Voltage Limit Lx Switch On % 1.0 V Note2 Unless otherwise provided, VIN=3V, Vss=0V, IOUT=10mA, Topt=25˚C, and use External Circuit of Typical Application (FIG. 1). (Note) 6 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 3µs. RH5RI • RH5RI302B VOUT=3.0V Symbol VOUT VIN Item Conditions Output Voltage MIN. TYP. MAX. Unit 2.925 3.000 3.075 V 8 V Input Voltage Oscillator Start-up Voltage EXT at no load,VOUT:0 →2V 0.7 0.8 V IDD1 Supply Current 1 EXT at no load,VOUT=2.88V 30 50 µA IDD2 Supply Current 2 EXT at 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 Vstart fosc Maximum Oscillator 1.5 Note mA 80 100 120 kHz 65 75 85 % Frequency Maxdty Oscillator Duty Cycle VEXT “H” side Unless otherwise provided, VIN=1.8V, Vss=0V, IOUT=10mA, Topt=25˚C, and use External Circuit of Typical Application (FIG. 2). • RH5RI502B VOUT=5.0V Symbol VOUT VIN Item Conditions Output Voltage MIN. TYP. MAX. Unit 4.875 5.000 5.125 V 8 V Input Voltage Oscillator Start-up Voltage EXT at no load,VOUT:0→2V 0.7 0.8 V IDD1 Supply Current 1 EXT at no load,VOUT=4.8V 60 90 µA IDD2 Supply Current 2 EXT at 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 Vstart fosc Maximum Oscillator 2 Note mA 80 100 120 kHz 65 75 85 % Frequency Maxdty Oscillator Duty Cycle VEXT “H” side Unless otherwise provided, VIN=3V, Vss=0V, IOUT=10mA, Topt=25˚C, and use External Circuit of Typical Application (FIG. 2). 7 RH5RI • RH5RI303B VOUT=3.0V Symbol VOUT VIN Item Conditions Output Voltage 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 MIN. Input Current 1 IIN2 Input Current 2 ILX Lx Switching Current 0.7 70 Efficiency IIN1 0.8 To be measured at VIN at no load To be measured at VIN VIN=3.5V VLX=0.4V V 80 % 4 8 µA 2 5 µA 60 mA ILXleak Lx Leakage Current VLX=6V,VIN=3.5V 0.5 µA IEXTH EXT “H” Output Current VEXT=VOUT –0.4V –1.5 mA IEXTL EXT “L” Output Current VEXT=0.4V 1.5 mA 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 Maximum Oscillator Maxdty Oscillator Duty Cycle VLXlim VLX Voltage Limit 0.4 VOUT–0.1 V V –0.5 µA 80 100 120 kHz on (VLX “L” )side 65 75 85 % Lx Switch on 0.65 0.8 1.0 V Frequency Note Note Unless otherwise provided, VIN=1.8V, VSS=0V, IOUT=10mA, Topt=25˚C, 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 3µs. 8 RH5RI • RH5RI503B VOUT=5.0V Symbol VOUT VIN Item Conditions Output Voltage 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 MIN. Efficiency IIN1 Input Current 1 IIN2 Input Current 2 ILX Lx Switching Current 0.8 0.7 70 To be measured at VIN at no load To be measured at VIN VIN=5.5V VLX=0.4V V 85 % 6 12 µA 2 5 µA 80 mA ILXleak Lx Leakage Current VLX=6V,VIN=5.5V 0.5 µA 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 Maximum Oscillator Maxdty Oscillator Duty Cycle VLXlim VLX Voltage Limit 0.4 VOUT–0.1 V V –0.5 µA 80 100 120 kHz on (VLX “L” )side 65 75 85 % Lx Switch on 0.65 0.8 1.0 V Frequency Note Note Unless otherwise provided, VIN=3V, VSS=0V, IOUT=10mA, Topt=25˚C 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 3µs. 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 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 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 topen≤toff 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=∫0ton (VIN · IL (t)) dt=∫0 (VIN2 · t/L) dt =VIN2 · ton2/(2 · L).................................................................................................... Equation 2 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 (VIN · (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 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 RH5RI ×× 2B and RH5RI ×× 3B 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 3.0 1.0V VIN=0.9V 2.0V 2.0 1.5 1.0 0.5 0 0 60 40 80 Output Current IOUT(mA) RH5RI501B Output Voltage VOUT(V) 3.5 3.0V 3.0 1.0V 2.5 VIN=0.9V 2.0 1.5 1.0 0.5 4.0V 2.0V VIN=0.9V 3 2 1 20 4.0V 5 40 80 60 Output Current IOUT(mA) 2.0V 3 VIN=0.9V 2 1 100 0 20 3.5 1.0V VIN=0.9V 2.0V 3.0V 2.5 2.0 1.5 1.0 0.5 400 200 Output Current IOUT(mA) 600 L=28µH 6 5 4 VIN=0.9V 100 80 40 60 Output Current IOUT(mA) RH5RI502B L=28µH Output Voltage VOUT(V) Output Voltage VOUT(V) 3.0V 1.5V 4 0 20 4.0 12 L=120µH 6 RH5RI352B 0 0 100 40 60 80 Output Current IOUT(mA) RH5RI501B L=82µH 3.0V 1.5V 4 0 100 5 3.0 2.0V 0 20 6 0 0 Output Voltage VOUT(V) 3.0V L=120µH 4.0 Output Voltage VOUT(V) Output Voltage VOUT(V) 3.5 2.5 RH5RI351B L=82µH 4.0 1.5V 2.0V 3.0V 4.0V 3 2 1 0 0 200 400 Output Current IOUT(mA) 600 RH5RI 2) Efficiency vs. Output Current 100 90 80 70 1.0V 60 V IN =0.9V 50 40 30 20 10 0 20 0 RH5RI351B L=82µH 3.0V Efficiency η(%) Efficiency η(%) RH5RI351B 2.0V 60 40 80 Output Current IOUT(mA) 100 RH5RI501B RH5RI501B Efficiency η(%) RH5RI352B 1.0V VIN=0.9V 0 2.0V Efficiency η(%) 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) 3.0V 400 200 Output Current I OUT(mA) 600 L=120µH 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) RH5RI502B L=28µH Efficiency η(%) Efficiency η(%) L=82µH 100 90 80 70 60 50 40 30 20 10 0 L=120µH 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) L=28µH 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) 13 RH5RI 3) Output Current vs.Ripple Voltage 100 80 3.0V 60 2.0V 1.5V 40 RH5RI351B L=82µH Ripple Voltage Vr (mV p-p) Ripple Voltage Vr (mV p-p) RH5RI351A 120 20 100 80 3.0V 60 1.5V 20 VIN=0.9V 40 60 80 Output Current IOUT(mA) Ripple Voltage Vr (mV p-p) RH5RI501B 0 100 0 100 4.0V 80 3.0V 60 2.0V 40 20 VIN=0.9V 0 40 20 60 80 Output Current IOUT(mA) 120 4.0V 100 3.0V 80 60 2.0V 40 20 VIN=0.9V 20 40 60 80 Output Current IOUT(mA) RH5RI502B L=28µH 250 2.0V 3.0V 1.5V VIN=0.9V 0 14 100 100 200 300 Output Current IOUT(mA) 400 100 L=120µH 140 0 0 Ripple Voltage Vr (mV p-p) Ripple Voltage Vr (mV p-p) RH5RI352B 200 180 160 140 120 100 80 60 40 20 0 40 20 60 80 Output Current I OUT(mA) RH5RI501B L=82µH Ripple Voltage Vr (mV p-p) 20 120 0 2.0V 40 VIN=0.9V 0 0 L=120µH 120 3.0V 100 L=28µH 4.0V 200 2.0V 150 100 50 VIN=0.9V 0 0 200 400 Output Current IOUT(mA) 600 RH5RI L=82µH 1.2 1.0 Vstart 0.8 0.6 Vhold 0.4 0.2 0 0 5 10 Output Current IOUT(mA) 15 RH5RI352B L=28µH 2.5 2.0 1.5 Vstart 1.0 Vhold 0.5 0 100 150 50 Output Current IOUT(mA) 0 200 5) Output Voltage vs. Temperature Start-up/Hold-on Voltage Vstart/Vhold (V) RH5RI351B Start-up/Hold-on Voltage Vstart/Vhold (V) Start-up/Hold-on Voltage Vstart/Vhold (V) Start-up/Hold-on Voltage Vstart/Vhold (V) 4) Start-up/Hold-on Voltage vs. Output Current RH5RI501B 1.6 1.4 1.2 1.0 Vstart 0.8 0.6 Vhold 0.4 0.2 0 0 10 5 Output Current I OUT(mA) RH5RI502B L=28µH 2.5 2.0 Vstart 1.5 1.0 Vhold 0.5 0 150 100 50 Output Current IOUT(mA) 0 RH5RI501B Start-up Voltage Vstart(V) Output Voltage VOUT(V) 5.10 5.05 5.00 4.95 4.90 4.85 20 0 40 Temperature Topt(˚C) 200 RH5RI501B 5.15 –20 15 6) Start-up Voltage vs. Temperature 5.20 4.80 –40 L=82µH 60 80 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –40 –20 20 0 40 Temperature Topt(˚C) 60 80 15 RH5RI 7) Hold-on Voltage vs. Temperature 8) Supply Current 1 vs.Temperature RH5RI501B RH5RI502B 60 Supply Current IDD1( µA) Hold-on Voltage Vhold (V) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 –40 –20 0 20 40 Temperature Topt(˚C) 60 50 40 30 20 10 0 –40 80 –20 RH5RI501B Lx Switching Current ILX (mA) 1.2 1.0 0.8 0.6 0.4 60 80 11) Lx Leakage Current vs.Temperature Lx Leakage Current ILXleak( µA) RH5RI501B 0.30 0.25 0.20 0.15 0.10 0.05 0 –40 16 –20 20 0 40 Temperature Topt(˚C) 60 200 180 160 140 120 100 80 60 40 20 0 –40 –20 0 20 40 Temperature Topt(˚C) 60 80 12) Maximum Oscillator Frequency vs.Temperature 80 Maximum Oscillator Frequency fosc (kHz) Input Current IIN2( µA) 1.6 1.4 0 20 40 Temperature Topt(˚C) 80 RH5RI501B 1.8 –20 60 10) Lx Switching Current vs.Temperature 9) Input Current 2 vs.Temperature 0.2 0 –40 0 20 40 Temperature Topt(˚C) RH5RI501B 160 140 120 100 80 60 40 20 0 –40 –20 40 0 20 Temperature Topt(˚C) 60 80 RH5RI 13) Oscillatar Duty Cycle vs. Temperature 14) Vlx Voltage Limit vs. Temperature RH5RI501B 1.00 VLX Voltage Limit VLXlim(V) Oscillator Duty Cycle Maxdty(%) RH5RI501B 100 90 80 70 60 50 –40 –20 20 0 40 Temperature Topt(˚C) 60 80 –20 RH5RI502B 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 –40 –20 20 0 40 Temperature Topt(˚C) 20 0 40 Temperature Topt(˚C) 60 80 60 80 16) Output Current vs. Temperature EXT "L" Output Current IEXTL(mA) EXT "H" Output Current IEXTH(mA) 15) Output Current vs. Temperature 0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 –40 60 80 RH5RI502B 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 –40 –20 0 20 40 Temperature Topt(˚C) 17 RH5RI TYPICAL APPLICATIONS • RH5RI ×× 1B Diode Inductor VOUT Lx OUT Vss + VIN Capacitor Components Inductor (L) Diode (D) : 82µH (Sumida Electric Co., Ltd.) : MA721 (Matsushita Electronics Corporation, Schottky Type) Capacitor (CL) : 22µF (Tantalum Type) FIG. 1 • RH5RI ×× 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 18 + RH5RI • RH5RI ×× 3B Diode Inductor VOUT Lx NC OUT EXT CE Vss + VIN Capacitor Components Inductor (L) : 82µH (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 19 RH5RI • CE pin Drive Circuit Diode Inductor RH5RI ×× 3B Lx NC VOUT OUT EXT CE Vss Pull-up resistor + Capacitor VIN CE Tr FIG. 5 20 RH5RI APPLICATION CIRCUITS • 12V Step-up Circuit Inductor Diode VOUT RH5RI502B 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 RH5RI ××1B VIN OUT Lx Rb1 Vss + Capacitor Starter Circuit (Note) When the Lx pin Voltage is over the rating at the time PNP Tr is OFF,use a RH5RI ×× 2B and drive the PNP Tr. by the external NPN Tr. FIG. 7 21 RH5RI • Step-up/Step-down Circuit with Flyback Diode Trance1:1 VOUT RH5RI ××1B OUT Lx VIN + Vss Capacitor Starter Circuit (Note) Use a RH5RI ×× 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 1.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) 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 10µF 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. 23