RN5RY202

VFM STEP-UP DC/DC CONVERTER CONTROLLER RN5RY202 NO.EA-042-0006 OUTLINE The RN5RY202 Series are VFM (chopper) Control ICs for step-up DC/DC converter with an external power transistor featuring high output voltage accuracy and low supply current by CMOS process. Each of the RN5RY202 Series ICs consists of a voltage reference unit, an error amplifier, an oscillator, a VFM control circuit and feed back resistors. Output voltage is fixed at 2V in the IC. A low ripple, high efficiency step-up DC/DC converter can be constructed by simply adding an inductor, a diode, a capacitor, and a drive transistor and feed back resistors. Although the series have no CE pins unlike RN5RY××1A, high voltage (VOUT=30V) can be also output by using external feed back resistors. FEATURES • Low Supply Current ............................................................................TYP. 3µA • Low Temperature-Drift Coefficient of Output Voltage ...................TYP. ±50ppm/˚C • High Accuracy Output Voltage .........................................................±2.5% • Low Oscillation Start-up Voltage (no load) ......................................MAX. 0.8V • Any output voltage can be set with external resistors • Small Package SOT-23-5 (Mini-Mold) APPLICATIONS • Constant voltage power source for battery-powered instruments. • Constant power source for cameras, camcorders, pagers, and other hand-held communication tools. • Constant power source for devices that require higher voltages than battery voltages. BLOCK DIAGRAM VDD 2 Oscillator 3 VOUT 5 EXT Output Buffer – + Vref 1 GND 1 R N5RY202 SELECTION GUIDE In the RN5RY202 Series, the taping type for the ICs can be selected at the user's request. These selections can be made by designating the part number as shown below: RN5RY202 × – ×× ←Part Number { ↑↑ ↑ ab c { ↑ d Code a b 20. Designation of Output Voltage (VOUT) VOUT is fixed at 2.0V. 2 Designation of Packing Type : c A : Taping C : Antistatic bag (for Samples only) Designation of Taping Type : Contents d Ex. TR, TL (refer to Taping Specifications ; TR type is prescribed as a standard.) For example, Taping Type TR, is designated by Part Number RN5RY202A-TR. PIN CONFIGURATION • SOT-23-5 5 4 mark side 1 2 3 2 R N5RY202 PIN DESCRIPTION Pin No. Symbol Description 1 2 3 4 5 GND VDD EXT NC VOUT Ground Pin Input Pin External Transistor Drive Pin (CMOS Output) No Connection Internal Voltage Output Pin (fixed at 2V) ABSOLUTE MAXIMUM RATINGS Symbol Item Ratings Unit VDD VOUT VEXT IEXT PD Topt Tstg Tsolder Input Voltage Output Pin Voltage EXT Pin Output Voltage EXT Pin Output Current Power Dissipation Operating Temperature Storage Temperature Lead Temperature (Soldering) 12 12 –0.3 to VDD+0.3 ±50 150 –40 to +85 –55 to +125 260˚C 10s (Lead part) V V V mA mW ˚C ˚C 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. 3 R N5RY202 ELECTRICAL CHARACTERISTICS • RN5RY202 Symbol Item Conditions MIN. TYP. MAX. Topt=25˚C Unit VOUT VIN IDD1 Output Voltage Input Voltage Supply Current 1 VIN=VDD=1.9V 1.950 2.000 2.050 10 V V µA EXT No load, VDD=1.9V VOUT=1.9V, Test circuits1 EXT No load, VDD=1.9V VOUT=2.1V, Test circuits1 VDD=1.9V, VOUT=1.9V Test circuits2 VDD=1.9V, VOUT=1.9V EXT “H” side, Test circuits2 EXT No load, Test circuits2 IOUT=10mA –40˚C≤Topt≤85˚C VDD=1.9V, VOUT=1.9V VEXT=GND, Test circuits3 VDD=1.9V, VOUT=1.9V VEXT=1.9V, Test circuits4 VDD=2V, VOUT=10V Test circuits5 1.5 65 15 25 IDD2 Supply Curren 2 3 5 µA fosc Duty Vstart ∆VOUT ∆Topt IEXTH Maximum Oscillator Frequency 180 kHz Oscillator Duty Cycle Oscillator Start-up Voltage Output Voltage Temperature Coefficient EXT “H” Output Current 75 0.7 ±50 0.8 % v ppm/˚C –1.5 mA IEXTL EXT “L” Output Current mA MΩ RVSET Voltage Set Resistor 2 4 R N5RY202 TEST CIRCUIT GND VOUT A VDD EXT NC Oscilloscope A GND VOUT VDD EXT NC Test Circuit1 Test Circuit2 GND VOUT VDD EXT Oscilloscope NC Oscilloscope GND VOUT VDD EXT NC Test Circuit3 Test Circuit4 GND VOUT VDD EXT NC A Test Circuit5 5 R N5RY202 TYPICAL CHARACTERISTICS 1) Output Voltage vs. Output Current 2SK2054(NEC) 40 40 2SK1470(Sanyo) Output Voltage VOUT(V) 35 Output Voltage VOUT(V) 0 20 40 60 35 30 30 25 25 20 20 0 20 40 60 Output Current IOUT(mA) Output Current IOUT(mA) 2) Efficiency vs. Output Current 2SK2054(NEC) 80 70 80 70 2SK1470(Sanyo) Efficiency η(%) Efficiency η(%) 60 50 40 30 20 0 20 40 60 60 50 40 30 20 0 20 40 60 Output Current IOUT(mA) Output Current IOUT(mA) *) VIN=3.6V **) For test circuit details, see “TYPICAL APPLICATIONS”. 6 R N5RY202 CHARACTERISTIC TEST CIRCUIT L1 D1 VIN VOUT VDD R1 RN5RY202 Q1 EXT VOUT + (2V) C R2 GND Components : Inductor (L1) Diode (D1) Capacitor (C) Transistor (Q1) Output voltage setting resistor (R1) Output voltage setting resistor (R2) : CD54 (15µH) : RB111C (Rohm) : 47µF (Tantalum type) : 2SK2054 (NEC) or 2SK1470 (Sanyo) : 150kΩ : 10kΩ TYPICAL APPLICATIONS SD1 L1 R2 VDD C1 EXT R1 GND VOUT R3 C2 7 RN5RY202 NOTES ON EXTERNAL COMPONENTS • If input voltage is high enough, higher efficiency may be obtained by using MOSFET in the driver transistor, in which case no resistors and condensers are necessary. • Always keep the absolute maximum ratings (VDS and VCE) since spike voltage higher than output voltage may be applied to the driver transistor. We recommend that you use transistors with absolute maximum ratings more than twice of the output setting voltage. • Use capacitor with an allowable voltage which is at least one and a half times as much as the setting output voltage. • Use output voltage setting resistors with resistance much smaller than IC internal resistor (MIN. 2MΩ). Be careful not to allow larger resistance, which will result in larger error in setting voltage. We recommend resistors up to several tens of kΩ. • Select an inductor with small DC resistance and enough permissible current and less tendency to magnetic saturation. • Select a diode of a shot-key type with a faster switching speed. Also pay attention to current capacity. (Reference external components) • Inductor CD54, CD73, CD104 (Sumida) • Driver transistor 2SD1628 (Sanyo) 2SK1470 (Sanyo) 2SK1959 (NEC) 2SK2054 (NEC) • Diode RB111C (Rohm) D1FS4A (Shindengen) • Output condenser Tantalum type 8 RN5RY202 NOTES ON OUTPUT VOLTAGE SETTINGS R2 VOUT RIC GND I2 VOUT I3 2.0V IIC R3 Output setting voltage is determined using the following formulas : I2=IIC+I3 ..........................................................................................(1) I3=2.0/R3 ........................................................................................(2) From (1) and (2) above, I2=IIC+2.0/R3 ..................................................................................(3) VOUT=2.0+R2 × I2............................................................................(4) By substituting (3) into the above formula VOUT=2.0+R2 × (IIC+2.0/R3) =2.0 × (1+R2/R3)+R2 × IIC ....................................................(5) The second term, R2 × IIC in the formula (5) above may cause a voltage setting error. Here, consider the formula in terms of IIC, IIC=2.0/RIC .....................................................................................(6) then R2 × IIC that causes the error will be as shown below : R2 × IIC=R2 × 2.0/RIC =2.0 × R2/RIC......................................................................(7) Thus, when R2