RH5RH751A-T1

PWM STEP-UP DC/DC CONVERTER RH5RH ×× 1A/ ××2B/ ××3B SERIES APPLICATION MANUAL NO.EA-023-0006 PWM STEP-UP DC/DC CONVERTER RH5RH ×× 1A/ ×× 2B/ ×× 3B SERIES OUTLINE The RH5RH ×× 1A/ ×× 2B/ ×× 3B Series are PWM Step-up DC/DC converter ICs by CMOS process. The RH5RH ×× 1A IC consists of an oscillator, a PWM control circuit, a driver transistor (Lx switch), a reference voltage unit, an error amplifier, a phase compensation circuit, resistors for voltage detection, a soft-start circuit, and an Lx switch protection circuit. A low ripple, high efficiency step-up DC/DC converter can be constructed of this RH5RH ×× 1A IC with only three external components, that is, an inductor, a diode and a capacitor. These RH5RH×× 1A/ ×× 2B/×× 3B ICs can achieve ultra-low supply current (no load) –TYP. 15µA –by a newly developed PWM control circuit, equivalent to the low supply current of a VFM (chopper) Step-up DC/DC converter. Furthermore, these ICs can hold down the supply current to TYP. 2µA by stopping the operation of the oscillator when the input voltage > (the output voltage set value + the dropout voltage by the diode and the inductor). These RH5RH×× 1A/×× 2B/×× 3B Series ICs are recommendable to the user who desires a low ripple PWM DC/DC converter, but cannot adopt a conventional PWM DC/DC converter because of its too large supply current. The RH5RH×× 2B/×× 3B Series ICs use the same chip as that employed in the RH5RH×× 1A IC and are provided with a drive pin (EXT) for an external transistor. Because of the use of the drive pin (EXT), an external transistor with a low saturation voltage can be used so that a large current can be caused to flow through the inductor and accordingly a large output current can be obtained. Therefore, these RH5RH×× 2B/×× 3B Series ICs are recommendable to the user who need a current as large as several tens mA to several hundreds mA. The RH5RH×× 3B IC also includes an internal chip enable circuit so that it is possible to set the standby supply current at MAX. 0.5µA. These RH5RH×× 1A/×× 2B/×× 3B ICs are suitable for use with battery-powered instruments with low noise and low supply current. FEATURES • Small Number of External Components ..........Only an inductor, a diode and a capacitor (RH5RH ×× 1A) • Low Supply Current ...........................................TYP. 15µA (RH5RH301A) • Low Ripple and Low Noise • Low Start-up Voltage (when the output current is 1mA) ..................MAX. 0.9V • High Output Voltage Accuracy..........................±2.5% • High Efficiency ...................................................TYP. 85% • Low Temperature-Drift Coefficient of Output Voltage ......................TYP. ±50 ppm/˚C • Soft-Start .............................................................MIN. 500µs • Small Packages ...................................................SOT-89 (RH5RH ×× 1A, RH5RH ×× 2B), SOT-89-5 (RH5RH ×× 3B) APPLICATIONS • Power source for battery-powered equipment. • Power source for cameras, camcorders, VCRs, PDAs, electronic data banks,and hand-held communication equipment. • Power source for instruments which require low noise and low supply current, such as hand-held audio equip- ment. • Power source for appliances which require higher cell voltage than that of batteries used in the appliances. 1 RH5RH BLOCK DIAGRAM 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 RH5RH ×× 1A and RH5RH ×× 3B EXT Pin .........only for RH5RH ×× 2B and RH5RH ×× 3B CE Pin ...........only for RH5RH ×× 3B SELECTION GUIDE In RH5RH Series, the output voltage, the driver, and the taping type for the ICs can be selected at the user's request. The selection can be made by designating the part number as shown below : RH5RH ×××× – × × ← Part Number ↑↑ ↑ 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. ×× 1B 1 2 3 — — ×× 2B 1 2 — 3 — ×× 3B 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 +125 260˚C,10s (Note 2) Applicable to RH5RH ×× 2B and RH5RH ×× 3B. V V V V mA mA mW ˚C ˚C Note1 Note2 Note3 Note1 Note2 (Note 1) Applicable to RH5RH ×× 1A and RH5RH ×× 3B. (Note 3) Applicable to RH5RH ×× 3B. ABSOLUTE MAXIMUM RATINGS Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under any conditions. Moreover, such values for any two items must not be reached simultaneously. Operation above these absolute maximum ratings may cause degradation or permanent damage to the device. These are stress ratings only and do not necessarily imply functional operation below these limits. 4 RH5RH ELECTRICAL CHARACTERISTICS • RH5RH301A 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 : 0→2V IOUT=1mA,VIN : 2→0V 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 µA IDD2 Supply Current 2 (excluding Switching Current) VIN=3.5V 2 5 µA ILX ILXleak fosc Maxdty η 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 µA 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=25˚C, and use External Circuit of Typical Application (FIG. 1). (Note 1) Soft-Start Circuit is operated in the following sequence : (1) VIN is applied. (2) The voltage (Vref) of the reference voltage unit is maintained at 0V for about 200µs after the application of VIN. (3) The output of Error Amp. is raised to “H” level during the maintenance of the voltage (Vref) of the reference voltage unit. (4) After the rise of Vref, the output of Internal Error Amp. is gradually decreased to an appropriate value by the function of Internal Phase Compensation Circuit, and the Output Voltage is gradually increased in accordance with the gradual decrease of the output of Internal Error Amp. (Note 2) ILX is gradually increased after Lx Switch is turned ON. In accordance with the increase of ILX, VLX is also increased. When VLX reaches VLXlim, Lx Switch is turned OFF by an Lx Switch Protection Circuit. 5 RH5RH • RH5RH501A 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:0→2V Iout=1mA,Vin:2→0V 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 µA IDD2 Supply Current 2 (excluding Switching Current) VIN=5.5V 2 5 µA ILX ILXleak fosc Maxdty η 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 µA 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=25˚C, and use External Circuit of Typical Application (FIG. 1). (Note 1) Soft-Start Circuit is operated in the following sequence : (1) VIN is applied. (2) The voltage (Vref) of the reference voltage unit is maintained at 0V for about 200µs after the application of VIN. (3) The output of Error Amp. is raised to “H” level during the maintenance of the voltage (Vref) of the reference voltage unit. (4) After the rise of Vref, the output of Internal Error Amp. is gradually decreased to an appropriate value by the function of Internal Phase Compensation Circuit, and the Output Voltage is gradually increased in accordance with the gradual decrease of the output of Internal Error Amp. (Note 2) ILX is gradually increased after Lx Switch is turned ON. In accordance with the increase of ILX, VLX is also increased. When VLX reaches VLXlim, Lx Switch is turned OFF by an Lx Switch Protection Circuit. 6 RH5RH • RH5RH302B 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 :0→2V 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 µA µA 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=25˚C, 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 :0→2V 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 µA µA 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=25˚C 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 η 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 VOUT≥1.5V VOUT≥1.5V 0.8V≤VOUT