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| Preliminary RT9261B VFM Step-up DC/DC Converter General Description The RT9261B Series are VFM Step-up DC/DC converter ICs with ultra low supply current by CMOS process and suitable for use with battery-powered instruments. The RT9261B 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 a LX switch protection circuit. A low ripple and high efficiency step-up DC/DC converter can be constructed with the RT9261B IC and only three external components. Features Minimal Number of External Components (Only an Inductor, a Diode, and a Capacitor) Ultra Low Input Current (6.5A at Switch Off) Capable of Supplying 50mA Output Current with Internal Switch 2% Output Voltage Accuracy Low Ripple and Low Noise Low Start-up Voltage, 0.8V at 1mA 80% Efficiency with Low Cost Inductor +50 ppm/C Low Temperature-Drift SOT-89 and SOT-25 Small Packages Applications The CE pin enables the circuit to set the standby supply current at a maximum of 0.5A. Power source for battery-powered equipment Power source for cameras, camcorders, VCRs, PDAs, pagers, electronic data banks, and handheld communication equipment Power source for appliances, which require higher voltage than that of batteries used in the appliances Ordering Information RT9261BPackage type B : SOT-25 X : SOT-89 Operating temperature range C: Commercial standard Output voltage 15 : 1.5V 16 : 1.6V : 49 : 4.9V 50 : 5.0V Pin Configurations Part Number RT9261BCX 1 2 3 Pin Configurations TOP VIEW 1. GND 2. VOUT (TAB) 3. LX TOP VIEW 5 4 (Plastic SOT-89) RT9261B- CB (Plastic SOT-25) 1 2 3 CE VOUT NC GND 5. LX 1. 2. 3. 4. DS9261B-03 September 2001 www.richtek-ic.com.tw 1 RT9261B Typical Application Circuit Preliminary D1 L1 VIN 27H 1N5819 RT9261B LX VOUT GND VOUT + - Co 22F D1 L1 VIN 27H 1N5819 RT9261B LX VOUT CE GND VOUT + Co - 22F * L1 ranges from 27H to 120H Pin Description Pin No. -xxCX 1 2 3 ---xxCB 4 2 5 1 3 Pin Name GND VOUT LX CE NC Ground Output Voltage Pin for Switching Chip Enable (Active High) No Connection Pin Function Function Block Diagram LX LXSW Buffer GND VFM Control OSC 190kHz Chip Enable + Error Amp. VOUT VLX Limiter Vref CE www.richtek-ic.com.tw DS9261B-03 September 2001 2 Preliminary Absolute Maximum Ratings Output Voltage LX Pin Voltage CE Pin Voltage (1) RT9261B 8V 8V -0.3 to VOUT +0.3V 400mA 0.5W 0.25W 100C/W 300C/W 250C/W -20 to +85C -65C to 150C 260C LX Pin Output Current Power Dissipation, PD @ TA = 25C SOT-89 SOT-25 Package Thermal Resistance SOT-89, JC SOT-89, JA SOT-25, JA Operating Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 sec.) Notes: (1) Applicable to RT9261B-xxCB Electrical Characteristics (Refer to Fig. 1) Parameter Output Voltage Accuracy Input Voltage Start-up Voltage Hold-on Voltage Input Current 1 (1) (2) (1) (2) (1) (2) Symbol VOUT VIN VST VHO Test Conditions Min -2 --0.7 -----120 160 -140 65 -0.65 Typ --0.8 -24 36 6.5 18 20 ---190 75 80 0.8 Max Units +2 7 1 -36 45 10 36 45 --0.5 240 85 -1.0 A % V V V A A IOUT = 1mA, VIN: 0 2V IOUT = 1mA, VIN: 2 0V To be measured at VIN in continuous switching To be measured at VOUT in switch off condition VOUT 3.5V 3.5V < VOUT 5V Input Current 2 Input Current 3 VOUT 3.5V 3.5V < VOUT 5V LX Switching Current LX Leakage Current Maximum Oscillator Frequency Oscillator Duty Cycle Efficiency VLX Voltage Limit Notes: VOUT 3.5V (1) To be measured at VIN in no load (guaranteed by I1 and I2) 3.5V < VOUT 5V (2) ISWITCHING VLX = 0.4V mA A KHz % % V ILEAKAGE FMAX DOSC VLX = 6V On (VLX "L") side LX switch on (1) VIN = 1.8V, VSS = 0V, IOUT = 1mA, Topt = 25C, and External Circuit of Typical Application (2) VIN = 3V, VSS = 0V, IOUT = 1mA, Topt = 25C, and External Circuit of Typical Application DS9261B-03 September 2001 www.richtek-ic.com.tw 3 RT9261B Parameter Output Voltage Accuracy Input Voltage Start-up Voltage Hold-on Voltage Efficiency Input Current 1 (1) (2) (1) (2) Preliminary Electrical Characteristics (Refer to Fig. 2) Symbol VOUT VIN VST VHO VOUT 3.5V IOUT = 1mA, VIN: 0 2V IOUT = 1mA, VIN: 2 0V Test Conditions Min -2 --0.7 -To be measured at VIN in continuous switching To be measured at VOUT in switch off condition VOUT 3.5V (1) (2) Typ --0.8 -80 24 36 6.5 18 20 -------190 75 0.8 Max Units +2 7 1 --36 45 10 36 45 --0.5 -0.2 0.5 -240 85 1.0 A % V V V % A A -----120 160 -0.4xVOUT ---0.5 140 65 0.65 3.5V < VOUT 5V Input Current 2 Input Current 3 3.5V < VOUT 5V LX Switching Current LX Leakage Current CE "H" Level CE "L" Level CE "H" Input Current CE " L" Input Current Maximum Oscillator Frequency Oscillator Duty Cycle VLX Voltage Limit Notes: VOUT 3.5V (1) To be measured at VIN in no load (guaranteed by I1 and I2) ISWITCHING VLX = 0.4V ILEAKAGE VLX = 6V VIN = VOUT * 0.9 VIN = VOUT * 0.9 CE = VOUT CE = 0V FMAX DOSC On (VLX "L") side LX switch on 3.5V < VOUT 5V (2) mA A V V A A KHz % V (1) VIN = 1.8V, VSS = 0V, IOUT = 1mA, Topt = 25C, and External Circuit of Typical Application (2) VIN = 3V, VSS = 0V, IOUT = 1mA, Topt = 25C, and External Circuit of Typical Application www.richtek-ic.com.tw DS9261B-03 September 2001 4 Preliminary Typical Operating Charateristics Start-up/Hold-on Voltage vs. Output Current Start-up/Hold-on Voltage Vstart/Vhold (V) 2.5 4.0 3.5 2 RT9261B Output Voltage vs. Output Current 3.0V 2.5V 2.0V Output Voltage (V) 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 1.0V 1.5V 1.5 Vstart Vhold 0.5 VOUT = 3.3V L = 47uH 0 30 60 90 120 150 180 1 0 VOUT = 3.3V L = 47uH 50 100 150 200 Output Current (mA) Output Current (mA) Output Current vs. Ripple Voltage 300 2.5V 250 2.0V 90 80 Output Current vs. Ripple Voltage 3.0V 2.0V Ripple Voltage (mVp-p) 200 150 100 50 1.0V 0 0 50 100 1.5V VOUT = 3.3V COUT = 20uF L = 47uH 150 200 Ripple Voltage (mVp-p) 3.0V 70 60 50 40 30 20 10 0 0 50 100 1.0V 1.5V VOUT = 3.3V COUT = 68uF L = 47uH 150 200 2.5V Output Current (mA) Output Current (mA) Output Current vs. Ripple Voltage 25 90 80 Efficiency vs. output Current 3.0V 2.5V 1.0V 1.5V 2.0V Ripple Voltage (mVp-p) 20 2.5V 15 3.0V 70 Efficiency (%) 60 50 40 30 20 10 0 0 50 100 10 1.0V 5 2.0V 1.5V 0 50 100 VOUT = 3.3V COUT = 170uF L = 47uH 150 200 0 VOUT = 3.3V L = 47uH 150 200 Output Current (mA) Output Current (mA) www.richtek-ic.com.tw DS9261B-03 September 2001 5 RT9261B Preliminary Start-up/Hold-on Voltage vs. Output Current Start-up/Hold-on Voltage Vstart/Vhold (V) 2.5 4.0 3.5 2 Output Voltage vs. Output Current 3.0V 1.5V 1.0V 2.0V 2.5V Output Voltage (V) 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 1.5 Vstart 1 0.5 Vhold VOUT = 3.3V L = 100uH 0 20 40 60 80 100 120 0 VOUT = 3.3V L = 100uH 50 100 150 200 Output Current (mA) Output Current (mA) Output Current vs. Ripple Voltage 300 2.0V 250 3.0V 90 80 Output Current vs. Ripple Voltage Ripple Voltage (mVp-p) 200 150 100 50 0 0 1.5V 1.0V 50 100 VOUT = 3.3V COUT = 20uF L = 100uH 150 200 2.5V Ripple Voltage (mVp-p) 70 60 50 40 30 20 10 0 0 1.5V 50 100 1.0V 2.0V 2.5V 3.0V VOUT = 3.3V COUT = 68uF L = 100uH 150 200 Output Current (mA) Output Current (mA) Output Current vs. Ripple Voltage 18 16 2.5V 2.0V 3.0V 100 90 80 70 1.0V Efficiency vs. output Current 3.0V 1.0V 2.5V Ripple Voltage (mVp-p) 14 12 10 8 6 4 2 0 0 Efficiency (%) 1.5V 2.0V 60 50 40 30 1.5V VOUT = 3.3V COUT = 170uF L = 100uH 100 150 200 20 10 0 0 50 100 VOUT = 3.3V L = 100uH 150 200 50 Output Current (mA) Output Current (mA) www.richtek-ic.com.tw DS9261B-03 September 2001 6 Preliminary Package Information D D1 A H RT9261B C B C1 e e A b b1 b Symbol A b B b1 C C1 D D1 e H Dimensions In Millimeters Min 1.397 0.356 2.388 0.406 -0.787 4.394 1.397 1.448 0.381 Max 1.600 0.483 2.591 0.533 4.242 1.194 4.597 1.753 1.549 0.432 Dimensions In Inches Min 0.055 0.014 0.094 0.016 -0.031 0.173 0.055 0.057 0.015 Max 0.063 0.019 0.102 0.021 0.167 0.047 0.181 0.069 0.061 0.017 3-Lead SOT-89 Surface Mount DS9261B-03 September 2001 www.richtek-ic.com.tw 7 RT9261B Preliminary D C B b A e L H A1 Symbol A A1 B b C D e H L Dimensions In Millimeters Min 0.889 0.000 1.397 0.356 2.591 2.692 0.838 0.102 0.356 Max 1.295 0.152 1.803 0.559 2.997 3.099 1.041 0.254 0.610 Dimensions In Inches Min 0.035 0.000 0.055 0.014 0.102 0.106 0.033 0.004 0.014 Max 0.051 0.006 0.071 0.022 0.118 0.122 0.041 0.010 0.024 SOT- 25 Surface Mount Package www.richtek-ic.com.tw DS9261B-03 September 2001 8 Preliminary RT9261B DS9261B-03 September 2001 www.richtek-ic.com.tw 9 RT9261B Preliminary RICHTEK TECHNOLOGY CORP. Headquarter 6F, No. 35, Hsintai Road, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5510047 Fax: (8863)5537749 RICHTEK TECHNOLOGY CORP. Taipei Office (Marketing) 8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek-ic.com.tw www.richtek-ic.com.tw DS9261B-03 September 2001 10 |
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