RT9261B. VFM Step-Up DC/DC Converter. General Description. Features. Ordering Information RT9261B- Package Type B : SOT-23-5 X : SOT-89.

Transcription

1 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. The EN pin enables the circuit to set the standby supply current at a maximum of.5μa. Features Minimal Number of External Components (Only an Inductor, a Diode, and a Capacitor) Ultra Low Input Current (6.5μA at Switch Off) Capable of Supplying 5mA Output Current with Internal Switch ± 2% Output Voltage Accuracy Low Ripple and Low Noise Low Start-up Voltage,.8V at 1mA 8% Efficiency with Low Cost Inductor +5 ppm/ C Low Temperature-Drift SOT-89 and SOT-23-5 Small Packages RoHS Compliant and 1% Lead (Pb)-Free Ordering Information RT9261B- Package Type B : SOT-23-5 X : SOT-89 Marking Information Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard) Output Voltage 15 : 16 : 1.6V : 49 : 4.9V 5 : 5.V Note : Richtek Pb-free and Green products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-2. Suitable for use in SnPb or Pb-free soldering processes. Applications Power source for battery-powered equipment Power source for cameras, camcorders, VCRs, PDAs, pagers, electronic data banks, and hand-held communication equipment Power source for appliances, which require higher voltage than that of batteries used in the appliances Pin Configurations (TOP VIEW) SOT For marking information, contact our sales representative directly or through a Richtek distributor located in your area, otherwise visit our website for detail. GND VOUT (TAB) LX 5 SOT-89 GND EN VOUT NC LX DS9261B-15 April 21 1

2 Typical Application Circuit D1 1N5819 V IN L1 RT9261B LX VOUT GND + C OUT 22µF V OUT D1 1N5819 V IN L1 RT9261B LX VOUT EN GND V OUT C OUT 22µF + * L1 ranges from 27μH to 12μH Functional Pin Description Pin No. SOT-23-5 SOT-89 Pin Name Pin Function 1 -- EN Chip Enable (Active High). 2 2 VOUT Output Voltage NC No Internal Connection. 4 1 GND Ground. 5 3 LX Pin for Switching. Function Block Diagram LX V LX Limiter V REF GND LXSW Buffer OSC 19kHz Chip Enable - + Error Amplifier VOUT EN 2 DS9261B-15 April 21

3 Absolute Maximum Ratings Output Voltage V LX Pin Voltage V EN Pin Voltage (1) to V OUT +.3V LX Pin Output Current mA Power Dissipation, P T A = 25 C SOT W SOT W Package Thermal Resistance SOT-89, θ JC C/W SOT-89, θ JA C/W SOT-23-5, θ JA C/W Operating Temperature Range to +85 C Storage Temperature Range C to 15 C Lead Temperature (Soldering, 1 sec.) C Notes: (1) Applicable to RT9261B-xxCB Electrical Characteristics (Refer to Figure 1) Parameter Symbol Test Conditions Min Typ Max Units Output Voltage Accuracy ΔV OUT % Input Voltage V IN V Start-up Voltage V ST I OUT = 1mA, V IN : 2V V Hold-on Voltage VHO IOUT = 1mA, VIN: 2 V V Input Current 1 VIN in continuous V OUT 3.5V (1) switching 3.5V < VOUT 5V (2) μa Input Current 2 (1) (2 ) V OUT in switch off condition μa Input Current 3 (guaranteed by I 1 and I 2 ) V IN in no load VOUT 3.5V (1) V < V OUT 5V (2) μa LX Switching Current I SWITCHING V LX =.4V VOUT 3.5V (1) V < V OUT 5V (2) LX Leakage Current ILEAKAGE VLX = 6V μa Maximum Oscillator Frequency FMAX V OUT = to 5V khz V OUT = to 2.4V khz Oscillator Duty Cycle DOSC On (VLX L ) side V OUT = to 5V % V OUT = to 2.4V % Efficiency % V LX Voltage Limit LX switch on V ma Notes: (1) V IN = 1.8V, V SS = V, I OUT = 1mA, Topt = 25 C, and use External Circuit of Typical Application (2) V IN = 3V, V SS = V, I OUT = 1mA, Topt= 25 C, and External Circuit of Typical Application DS9261B-15 April 21 3

4 Electrical Characteristics (Refer to Figure 2) Parameter Symbol Test Conditions Min Typ Max Units Output Voltage Accuracy ΔVOUT % Input Voltage V IN V Start-up Voltage VST IOUT = 1mA, VIN: 2V V Hold-on Voltage V HO I OUT = 1mA, V IN : 2 V V Efficiency % Input Current 1 V IN in continuous V OUT 3.5V (1) switching 3.5V < V OUT 5V (2) μa Input Current 2 (1) (2) V OUT in switch off condition μa Input Current 3 (guaranteed by V OUT 3.5V (1) V IN in no load I 1 and I 2) 3.5V < V OUT 5V (2) μa LX Switching Current I SWITCHING V LX =.4V VOUT 3.5V (1) V < V OUT 5V (2) ma LX Leakage Current I LEAKAGE V LX = 6V μa EN H Level V IN = V OU T *.9.4 x V OUT V EN L Level VIN = V OU T * V EN H Input Current EN = V OUT μa EN L Input Current EN = V μa Maximum Oscillator Frequency FMAX V OUT = to 5V khz V OUT = to 2.4V khz Oscillator Duty Cycle D OSC V OUT = to 5V % On (V LX L ) side V OUT = to 2.4V % V LX Voltage Limit LX switch on V Notes: (1) V IN = 1.8V, V SS = V, I OUT = 1mA, Topt = 25 C, and use External Circuit of Typical Application (2) V IN = 3V, V SS = V, I OUT = 1mA, Topt= 25 C, and External Circuit of Typical Application 4 DS9261B-15 April 21

5 Typical Operating Characteristics Start-up/Hold-on Voltage Vstart/Vhold (V)1 Start-up/Hold-on Voltage vs. Output Current Vstart Vhold Output Voltage (V) Output Voltage vs. Output Current 1.V Ripple Voltage (mvp-p) V COUT = 2μF Ripple Voltage (mvp-p) V COUT = 68μF Efficiency vs. output Current Ripple Voltage (mvp-p) V COUT = 17μF Efficiency (%) V DS9261B-15 April 21 5

6 Start-up/Hold-on Voltage Vstart/Vhold (V)1 2.5 Start-up/Hold-on Voltage vs. Output Current Vstart Vhold L = 1μH Output Voltage (V) Output Voltage vs. Output Current 1.V L = 1μH Ripple Voltage (mvp-p) V COUT = 2μF L = 1μH Ripple Voltage (mvp-p) V COUT = 68μF L = 1μH Efficiency vs. output Current Ripple Voltage (mvp-p) V COUT = 17μF L = 1μH Efficiency (%) V L = 1μH 6 DS9261B-15 April 21

7 Outline Dimension D H L C B b A A1 e Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A A B b C D e H L SOT-23-5 Surface Mount Package DS9261B-15 April 21 7

8 D D1 A C B C1 e e H A b b1 b Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A b B b C C D D e H Lead SOT-89 Surface Mount Richtek Technology Corporation Headquarter 5F, No. 2, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863) Fax: (8863) Richtek Technology Corporation Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862) Fax: (8862) marketing@richtek.com Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. 8 DS9261B-15 April 21