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PWM STEP-UP DC/DC CONVERTER
RH5RH××1A/××2B/××3B SERIES
APPLICATION MANUAL
ELECTRONIC DEVICES DIVISION
NO.EA-023-9803
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NOTICE 1. The products and the product specifications described in this application manual are subject to change or dis- continuation 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 con- sent of Ricoh. 3. Please be sure to take any necessary form
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RH5RH SERIES APPLICATION MANUAL CONTENTS ...................................................................................................... OUTLINE 1 .................................................................................................... FEATURES 1 ............................................................................................. APPLICATIONS 1 ......................................................................................... BLOCK DIAGRAM 2 ...................
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............................................................................ TYPICAL APPLICATIONS 23 ................................................................................................. • RH5RH· · 1A 23 .................................................................................................. • RH5RH· · 2B 23 .................................................................................................. • RH5RH· · 3B 24 ....................................................
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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 refer- ence voltage unit, an error amplifier, a phase compensation circuit, resistors for voltage detection, a soft-start cir- cuit, and an Lx switch protection circuit. A low ripple, high efficiency step-up DC/DC converter can be constr
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} } } RH5RH BLOCK DIAGRAM VLX limiter Slow start Vref Lx OUT Buffer Phase Comp. Vss 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
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RH5RH PIN CONFIGURATION • SOT-89 • SOT-89-5 5 4 (mark side) (mark side) 1 2 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 Switching Pin (Nch Open Drain) — 3 3 EXT External Tr. Drive Pin (CMOS Output) — — 1 CE Chip Enable Pin (Active Low) 3
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RH5RH ABSOLUTE MAXIMUM RATINGS Vss=0V Symbol Item Rating Unit Note VOUT 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 Topt Operating Temperature Range –30 to +80 ˚C Tstg Storage Temperature Range –55 to +125 ˚C Tsolder Lead Temperature(Soldering) 260˚C,10s (Note 1) Applicable to RH5RH· · 1A and
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RH5RH ELECTRICAL CHARACTERISTICS • RH5RH301A VOUT=3.0V Symbol Item Conditions MIN. TYP. MAX. Unit Note VOUT Output Voltage 2.925 3.000 3.075 V VIN Input Voltage 8 V Vstart Start-up Voltage IOUT=1mA,VIN : 0fi 2V 0.8 0.9 V Vhold Hold-on Voltage IOUT=1mA,VIN : 2fi 0V 0.7 V To be measured at OUT Pin IDD1 Supply Current 1 15 25 µA (excluding Switching Current) To be measured at OUT Pin IDD2 Supply Current 2 (excluding Switching Current) 2 5 µA VIN=3.5V ILX Lx Switching Current VLX=0.4V 60 mA ILXleak Lx
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RH5RH • RH5RH501A VOUT=5.0V Symbol Item Conditions MIN. TYP. MAX. Unit Note VOUT Output Voltage 4.875 5.000 5.125 V VIN Input Voltage 8 V Vstart Start-up Voltage Iout=1mA,Vin:0fi 2V 0.8 0.9 V Vhold Hold-on Voltage Iout=1mA,Vin:2fi 0V 0.7 V To be measured at OUT Pin IDD1 Supply Current 1 30 45 µA (excluding Switching Current) To be measured at OUT Pin IDD2 Supply Current 2 (excluding Switching Current) 2 5 µA VIN=5.5V ILX Lx Switching Current VLX=0.4V 80 mA ILXleak Lx Leakage Current VLX=6V,VIN=5.5
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RH5RH • RH5RH302B VOUT=3.0V Symbol Item Conditions MIN. TYP. MAX. Unit Note VOUT Output Voltage 2.925 3.000 3.075 V VIN Input Voltage 8 V Vstart Oscillator Start-up Voltage EXT no load,VOUT :0fi 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 Oscillator Frequency 80 100 120 kHz Oscillator Maximum Duty Maxdty VEXT “H” side 70 8
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RH5RH • RH5RH303B VOUT=3.0V Symbol Item Conditions MIN. TYP. MAX. Unit Note VOUT Output Voltage 2.925 3.000 3.075 V VIN Input Voltage 8 V fi Vstart Start-up Voltage IOUT=1mA,VIN : 0 2V 0.8 0.9 V fi Vhold Hold-on Voltage IOUT=1mA,VIN : 2 0V 0.7 V h Efficiency 70 85 % IDD1 Supply Current 1 To be measured at OUT pin 30 50 µA To be measured at OUT pin 2 5 µA IDD2 Supply Current 2 VIN=3.5V ILX Lx Switching Current VLX=0.4V 60 mA VLX=6V,VIN=3.5V 0.5 µA ILXleak Lx Leakage Current IEXTH EXT “H” Output Cu
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RH5RH • RH5RH503B VOUT=5.0V Symbol Item Conditions MIN. TYP. MAX. Unit Note VOUT Output Voltage 4.875 5.000 5.125 V VIN Input Voltage 8 V Vstart Start-up Voltage IOUT=1mA,VIN : 0fi 2V 0.8 0.9 V fi Vhold Hold-on Voltage IOUT=1mA,VIN : 2 0V 0.7 V h Efficiency 70 85 % IDD1 Supply Current 1 To be measured at OUT pin 60 90 µA To be measured at OUT pin IDD2 Supply Current 2 2 5 µA VIN=5.5V VLX=0.4V 80 mA ILX Lx Switching Current ILXleak Lx Leakage Current VLX=6V,VIN=5.5V 0.5 µA VEXT=VOUT–0.4V –2.0 mA IE
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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 ILmax ILmin L IOUT topen SD VIN VOUT i1 t Lx Tr CL toff ton T=1/fosc Step 1 : LxTr is tu
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RH5RH When the output current (IOUT) is relatively small, topen0). The former mode is referred to as the discon
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RH5RH Therefore it is necessary that the setting of the input/output conditions and the selection of peripheral compo- nents 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 · IO
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RH5RH TYPICAL CHARACTERISTICS 1) Output Voltage vs. Output Current RH5RH301A RH5RH301A L= 270µH L=120µH 3.1 3.1 3.0 3.0 2.9 2.9 2.8 2.8 2.7 2.7 1.5V 2.0V 1.5V 2.6 2.6 VIN=1.0V 2.0V VIN =1.0V 2.5 2.5 0 10 20 30 40 50 60 0 20 60 40 Output Current IOUT(mA) Output Current IOUT(mA) RH5RH501A RH5RH501A L=120µH L=270µH 5.2 5.2 5.0 5.0 4.0V 4.8 4.8 3.0V 4.6 4.6 2.0V 3.0V 2.0V 4.0V 4.4 4.4 4.2 4.2 VIN= VIN=1.0V 1.0V 4.0 4.0 0 50 100 150 0 50 100 150 Output Current IOUT(mA) Output Current IOUT(mA) RH5R
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RH5RH 2) Efficiency vs. Output Current RH5RH301A RH5RH301A L=120µH L=270µH 90 100 90 80 2.0V 80 70 2.0V 1.5V 70 60 60 VIN=1.0V VIN=1.0V 1.5V 50 50 40 40 0 10 20 30 0 10 20 30 40 Output Current IOUT(mA) Output Current IOUT(mA) RH5RH501A RH5RH501A L=120µH L=270µH 100 100 90 90 4.0V 80 80 4.0V 3.0V 70 70 VIN= 3.0V 2.0V 1.0V 60 60 VIN=1.0V 2.0V 50 50 40 40 0 50 100 150 0 50 100 150 Output Current IOUT(mA) Output Current IOUT(mA) RH5RH302B RH5RH502B L=28µH L = 28µH 100 100 80 80 4.0V 2.5V 3.0V 2.0V
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RH5RH 3) Supply Curret (No Load) vs. Input Voltage RH5RH301A RH5RH301A L=270µH L=120µH 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 1.0 1.2 1.4 1.6 1.8 2.0 1.0 1.2 1.4 1.6 1.8 2.0 Input Voltage VIN(V) Input Voltage VIN(V) RH5RH501A RH5RH501A L=120µH L=270µH 200 200 150 150 100 100 50 50 0 0 1 2 3 4 1 2 3 4 Input Voltage VIN(V) Input Voltage VIN(V) 4) Output Current vs.Ripple Voltage RH5RH301A RH5RH501A L=120µH L=120µH 100 80 90 70 2.0V 80 4.0V 3.0V 60 3.0V 70 2.0V 50 VIN=0.9V 60 40 50 VI
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RH5RH RH5RH301A RH5RH501A L=270µH L=270µH 80 70 70 60 60 50 4.0V 3.0V 50 3.0V 40 VIN=0.9V 40 2.0V 30 30 2.0V 20 20 10 10 VIN=0.9V 0 0 60 70 80 90 1 10 20 30 40 50 1 10 20 30 40 50 60 70 80 Output Current IOUT(mA) Output Current IOUT(mA) RH5RH302B RH5RH502B L=28µH L=28µH 70 120 VIN=0.9V 2.0V 60 100 2.0V 3.0V 3.0V 50 80 40 60 4.0V 30 40 20 VIN=0.9V 20 10 0 0 1 50 100 150 200 1 50 100 150 200 250 Output Current IOUT(mA) Output Current IOUT(mA) 5) Start-up/Hold-on Voltage vs. Output Current
