ST5R33MTR

ST5R00 SERIES MICROPOWER VFM STEP-UP DC/DC CONVERTER ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ VERY LOW SUPPLY CURRENT REGULATED OUTPUT VOLTAGE WIDE RANGE OF OUTPUT VOLTAGE AVAILABLE (2.5V, 2.8V, 3.0V, 3.3V, 5.0V) OUTPUT VOLTAGE ACCURACY ±5% OUTPUT CURRENT UP TO 100mA LOW RIPPLE AND LOW NOISE VERY LOW START-UP VOLTAGE HIGH EFFICIENCY (VOUT = 5V TYP. 87%) FEW EXTERNAL COMPONENTS VERY SMALL PACKAGE: SOT23-5L DESCRIPTION The ST5R00 is an high efficiency VFM Step-up DC/DC converter for small, low input voltage or battery powered systems with ultra low quiescent supply current. The ST5Rxx accept a positive input voltage from start-up voltage to VOUT and convert it to a higher output voltage in the 2.5 to 5V range. The ST5R00 combine ultra low quiescent supply current and high efficiency to give maximum battery life. The high switching frequency and the internally limited peak inductor current, permits SOT23-5L the use of small, low cost inductors. Only three external components are needed: an inductor a diode and an output capacitor. The ST5R00 is suitable to be used in a battery powered equipment where low noise, low ripple and ultra low supply current are required. The ST5R00 is available in very small packages: SOT23-5L. Typical applications are pagers, cameras & video camera, cellular telephones, wireless telephones, palmtop computer, battery backup supplies, battery powered equipment. Figure 1: Schematic Diagram June 2005 Rev. 6 1/15 ST5R00 SERIES Table 1: Absolute Maximum Ratings Symbol VOUT Parameter Value Unit Output Voltage 5.5 V VIN Input Voltage 5.5 V VLX LX Pin Voltage 5.5 V ILX LX Pin Output Current Internally limited PTOT Power Dissipation at 25°C TSTG Storage Temperature Range -55 to 125 °C TOP Operating Junction Temperature Range -25 to 85 °C 170 (*) mW (*) Reduced by 1.7 mW for increasing in TA of 1°C over 25°C Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. Table 2: Thermal Data Symbol Rthj-case Parameter Thermal Resistance Junction-case SOT23-5L Unit 63 °C/W Figure 2: Connection Diagram (top view) Table 3: Order Codes 2/15 SOT23-5L OUTPUT VOLTAGES ST5R25MTR ST5R28MTR ST5R30MTR ST5R33MTR ST5R50MTR 2.5 V 2.8 V 3.0 V 3.3 V 5.0 V ST5R00 SERIES OPERATION The ST5Rxx architecture is built around a VFM CONTROL logic core: switching frequency is set through a built in oscillator: TON time is fixed (Typ. 5ms) while TOFF time is determined by the error amplifier output, a logic signal coming from the comparison made by the Error Amplifier Stage between the signal coming from the output voltage divider network and the internal Band-Gap voltage reference (Vref). TOFF reaches a minimum (Typ. 1.7ms) when heavy load conditions are met (Clock frequency 150KHz). An over current conditions, through the internal power switch, causes a voltage drop VLX=R DSONxISW and the VLX limiter block forces the internal switch to be off, so narrowing TON time and limiting internal power dissipation. In this case the switching frequency may be higher than the 150KHz set by the internal clock generator. VFM control ensures very low quiescent current and high conversion efficiency even with very light loads. Since the Output Voltage pin is also used as the device Supply Voltage, the versions with higher output voltage present an higher internal supply voltage that results in lower power switch RDSON, slightly greater output power and higher efficiency. Moreover, bootstrapping allows the input voltage to sag to 0.6V (at IOUT=1mA) once the system is started. If the input voltage exceeds the output voltage, the output will follow the input, however, the input or output voltage must not be forced above 5.5V. Figure 3: Typical Application Circuit (*) See application info. Figure 4: Typical Application Efficiency 3/15 ST5R00 SERIES Figure 5: Typical Demoboard Note: drawing not in scale. Table 4: Electrical Characteristics For ST5R25 (VIN = 1.5V, IOUT = 10mA, TA = 25°C, unless otherwise specified. For external components value, unless otherwise notes, refer to the typical operating circuit.) Symbol VOUT Parameter Test Conditions Output Voltage Min. 2.375 Typ. Max. Unit 2.5 2.625 V 0.8 1.2 V VSTART-UP Start-up Voltage (VIN-VF) (1) IOUT = 1mA, VIN = rising from 0 to 2V VHOLD Hold-on Voltage IOUT = 1mA, VIN = falling from 2 to 0V ISUPPLY Supply Current To be measured at VIN, no load 16 µA ILX = 150mA 850 mΩ RLX(DSON) Internal Switch RDSON ILX(leak) Internal Leakage Current fOSC Dty ν 0.6 V VLX = 4V, forced VOUT = 3V 0.5 Maximum oscillator Frequency 150 µA KHz Oscillator Duty Cycle to be measure on LX pin 77 % Efficiency IOUT = 50mA 82 % (1): The minimum input voltage for the IC start-up is strictly a function of the VF catch diode. Table 5: Electrical Characteristics For ST5R28 (VIN = 1.7V, IOUT = 10mA, TA = 25°C, unless otherwise specified. For external components value, unless otherwise notes, refer to the typical operating circuit.) Symbol VOUT Parameter Test Conditions Output Voltage VSTART-UP Start-up Voltage (VIN-VF) (1) Min. 2.66 IOUT = 1mA, VIN = rising from 0 to 2V Typ. Max. 2.8 2.94 V 0.8 1.2 V VHOLD Hold-on Voltage IOUT = 1mA, VIN = falling from 2 to 0V ISUPPLY Supply Current To be measured at VIN, no load 16 µA ILX = 150mA 850 mΩ RLX(DSON) Internal Switch RDSON ILX(leak) Internal Leakage Current fOSC Dty ν V VLX = 4V, forced VOUT = 3.3V Maximum oscillator Frequency 0.5 150 µA KHz Oscillator Duty Cycle to be measure on LX pin 77 % Efficiency IOUT = 50mA 82 % (1): The minimum input voltage for the IC start-up is strictly a function of the VF catch diode. 4/15 0.6 Unit ST5R00 SERIES Table 6: Electrical Characteristics For ST5R30 (VIN = 1.8V, IOUT = 10mA, TA = 25°C, unless otherwise specified. For external components value, unless otherwise notes, refer to the typical operating circuit.) Symbol VOUT Parameter Test Conditions Output Voltage VSTART-UP Start-up Voltage (VIN-VF) (1) Min. Typ. Max. Unit 2.85 3 3.15 V 0.8 1.2 V IOUT = 1mA, VIN = rising from 0 to 2V VHOLD Hold-on Voltage IOUT = 1mA, VIN = falling from 2 to 0V ISUPPLY Supply Current To be measured at VIN, no load 17 µA ILX = 150mA 850 mΩ RLX(DSON) Internal Switch RDSON ILX(leak) Internal Leakage Current fOSC Dty ν 0.6 V VLX = 4V, forced VOUT = 3.5V 0.5 Maximum oscillator Frequency 150 µA KHz Oscillator Duty Cycle to be measure on LX pin 77 % Efficiency IOUT = 50mA 82 % (1): The minimum input voltage for the IC start-up is strictly a function of the VF catch diode. Table 7: Electrical Characteristics For ST5R33 (VIN = 2V, IOUT = 10mA, TA = 25°C, unless otherwise specified. For external components value, unless otherwise notes, refer to the typical operating circuit.) Symbol VOUT Parameter Test Conditions Output Voltage VSTART-UP Start-up Voltage (VIN-VF) (1) Min. 3.135 IOUT = 1mA, VIN = rising from 0 to 2V Typ. Max. 3.3 3.465 V 0.8 1.2 V VHOLD Hold-on Voltage IOUT = 1mA, VIN = falling from 2 to 0V ISUPPLY Supply Current To be measured at VIN, no load 17 ILX = 150mA 850 RLX(DSON) Internal Switch RDSON ILX(leak) fOSC Dty ν Internal Leakage Current 0.6 V VLX = 4V, forced VOUT = 3.8V µA mΩ 0.5 Maximum oscillator Frequency Unit µA 150 KHz Oscillator Duty Cycle to be measure on LX pin 77 % Efficiency IOUT = 50mA 83 % (1): The minimum input voltage for the IC start-up is strictly a function of the VF catch diode. Table 8: Electrical Characteristics For ST5R50 (VIN = 3V, IOUT = 10mA, TA = 25°C, unless otherwise specified. For external components value, unless otherwise notes, refer to the typical operating circuit.) Symbol VOUT Parameter Test Conditions Output Voltage Min. Typ. Max. Unit 4.75 5.0 5.25 V 0.8 1.2 V VSTART-UP Start-up Voltage (VIN-VF) (1) IOUT = 1mA, VIN = rising from 0 to 2V VHOLD Hold-on Voltage IOUT = 1mA, VIN = falling from 2 to 0V ISUPPLY Supply Current To be measured at VIN, no load 18 µA ILX = 150mA 700 mΩ RLX(DSON) Internal Switch RDSON ILX(leak) Internal Leakage Current fOSC Dty ν 0.6 V VLX = 4V, forced VOUT = 3.8V Maximum oscillator Frequency 0.5 µA 160 KHz Oscillator Duty Cycle to be measure on LX pin 77 % Efficiency IOUT = 50mA 87 % (1): The minimum input voltage for the IC start-up is strictly a function of the VF catch diode. 5/15 ST5R00 SERIES TYPICAL PERFORMANCE CHARACTERISTICS (the following plots are referred to the typical application circuit and, unless otherwise noted, at TA = 25°C) Figure 6: Output Voltage vs Output Current Figure 9: Output Voltage vs Temperature Figure 7: Output Voltage vs Output Current Figure 10: Efficiency vs Temperature Figure 8: Output Voltage vs Temperature Figure 11: Efficiency vs Temperature 6/15 ST5R00 SERIES Figure 12: Efficiency vs Output Current Figure 15: Maximum Oscillator Frequency vs Temperature Figure 13: Efficiency vs Output Current Figure 16: Oscillator Duty Cycle (@ MAX Freq.) vs Temperature Figure 14: Maximum Oscillator Frequency vs Temperature Figure 17: Oscillator Duty Cycle (@ MAX Freq.) vs Temperature 7/15 ST5R00 SERIES Figure 18: LX Switching Current Limit vs Temperature Figure 21: Start-up Voltage (VIN - VF) vs Temperature Figure 19: LX Switching Current Limit vs Temperature Figure 22: Start-up Voltage (VIN - VF) vs Output Current Figure 20: Start-up Voltage (VIN - VF) vs Temperature Figure 23: Start-up Voltage (VIN - VF) vs Output Current 8/15 ST5R00 SERIES Figure 24: Minimum Input Voltage vs Output Current Figure 27: Internal Switch RDSON vs Temperature Figure 25: Minimum Input Voltage vs Output Current Figure 28: Hold-on Voltage vs Temperature Figure 26: Internal Switch RDSON vs Temperature Figure 29: Hold-on Voltage vs Temperature 9/15 ST5R00 SERIES Figure 30: No Load Input Current vs Temperature Figure 31: No Load Input Current vs Temperature APPLICATION INFORMATION PC LAYOUT AND GROUNDING HINTS The ST5R00 high frequency operation makes PC layout important for minimizing ground bounce and noise. Place external components as close as possible to the device pins. Take care to the Supply Voltage Source connections that have to be very close to the Input of the application. Set the Output Load as close as possible to the output capacitor. If possible, use a Star ground connection with the centre point on the Device Ground pin. To maximize output power and efficiency and minimize output ripple voltage, use a ground plane and solder the ICs ground pin directly to the ground plane. Remember that the LX Switching Current flows through the Ground pin, so, in order to minimize the series resistance that may cause power dissipation and decrease of the Efficiency conversion, the Ground pattern has to be as large as possible. INDUCTOR SELECTION An inductor value of 47µH performs well in most ST5R00 applications. However, the inductance value is not critical, and the ST5R00 will work with inductors in the 33µH to 120µH. Smaller inductance values typically offer a smaller physical size for a given series resistance, allowing the smallest overall circuit dimensions. However, due to higher peak inductor currents, the output voltage ripple (Ipeak x output filter capacitors ESR) also tends to be higher. Circuits using larger inductance values exhibit higher output current capability and larger physical dimensions for a given series resistance. In order to obtain the best application performances the inductor must respect the following condition: - The DC resistance has to be as little as possible, a good value is