LESHAN RADIO COMPANY, LTD. LR90 9 8 TINY PACKAGE HIGH EFFICIENCY STEP-UP DC/DC CONVERTER Introduction The LR9908 is a CMOS step-up switching DC/DC converter that mainly Features • Low voltage operation: Oscillation start voltage at 0.8V consists of a reference voltage source, an • Duty ratio: 66/78%, built-in auto switching oscillator, and a comparator. The LR9908 • External parts: Coil, capacitor, diode, allows the duty ratio to be automatically NMOS switched according to the load (light load: • High efficiency：±85%（typ.） 66%, high output current: 78%), enabling • Output voltage Adjustable products with a low ripple over a wide • Providing Flexibility for Using External range, high efficiency, and high output Power Switches current. With the LR9908, a step-up • Zero Shutdown Mode Supply Current switching • 6µA Quiescent (Switch-off) Supply Current DC/DC converter can be configured by using an external coil, • Small SOT23-5,SOT89-5 Package capacitor, diode and NMOS. This feature, along with the mini package and low current consumption, makes the LR9908 ideal for applications such as the power supply unit of portable equipment. Applications • PDA • DSC • LCD Panel • RF-Tags • MP3 • Portable Instrument • Wireless Equipment Ordering Information LR9908 1/8 LESHAN RADIO COMPANY, LTD. Block Diagrams LR9908 Pin Assignment Pin No.（SOT23-5） Pin Functions LR9908A LR9908B Name 1 1 FB Feedback Input Pin 2 2 VDD IC power supply pin - 3 EN Chip Enable (Active High) 3 - NC No Connection 4 4 VSS GND pin 5 5 EXT External transistor connection pin Pin No.（SOT89-5） LR9908A Pin LR9908B Functions Name - 1 EN Chip Enable (Active High) 1 - NC No Connection 2 2 VDD IC power supply pin 3 3 FB Feedback Input Pin 4 4 EXT External transistor connection pin 5 5 VSS GND pin 2/8 LESHAN RADIO COMPANY, LTD. Absolute Maximum Ratings (Unless otherwise specified, Ta=25℃) Parameter VOUT pin voltage EN pin voltage Power dissipation SOT-23-5 SOT-89-5 Symbol Ratings Unit VOUT VSS－0.3 ~ VSS＋8 V EN VSS－0.3 ~ VSS＋8 V 250 mW 500 mW PD Operating temperature Topr －40 ~＋85 ℃ Storage temperature Tstg －40 ~＋125 ℃ Electrical Characteristics (Unless otherwise specified, Ta =25℃) Parameter Symbol Conditions Min. Typ. Max. Unit Feedback Voltage VFB － VFB(s) ×0.98 VFB VFB(s) ×1.02 V Input voltage VIN － － － 8 V 0.8 V No external parts, voltage applied to Oscillation start voltage VST Current consumption 1 ISS1 VCC=5V, Continuously Switching － 30 40 µA Current consumption 2 ISS2 VCC=5V, FB=2.5V, No Switching － 5 10 µA Shut Down Current ISSS VCC=5V,VEN=0 V － － 0.5 µA VOUT LX pulled up to VOUT via 300Ω resistor Line regulation ∆VOUT1 VIN= 0.4×VOUT～0.6×VOUT （VOUT=5V） － 20 50 mV Load regulation ∆VOUT2 IOUT= 10 µA ~ 50mA（VOUT=5V） － 20 50 mV Oscillation frequency fOSC 100 kHz Duty ratio 1 Duty1 VOUT= 0.95×VOUT， measure waveform at LX pin 70 78 85 % Duty ratio 2 Duty2 Measure waveform at LX pin with light load － 66 － % Efficiency EFFI Shutdown pin input voltage Shutdown pin input current VSH VSL1 85 VOUT=0.95×VOUT， judge oscillation at EXT pin VOUT= 0.95×VOUT， judge stop at EXT pin % 0.75 － － V － － 0.3 V ISH VEN＝8V － － 0.1 µA ISL VEN＝0V － － 0.1 µA Remark：1、VIN =VOUT(S) ×0.6 applied, IOUT=VOUT(S) / 250 Ω 2、Shutdown function built-in type: EN pin is connected to VOUT 3、VOUT(S) specified above is the set output voltage value, and VOUT is the typical value of the actual output voltage. 3/8 LESHAN RADIO COMPANY, LTD. ■ Standard Circuits Component: Inductor：22uH(Sumida) Capacitor：47uF (Tantalum type) Diode：IN5817、IN5819 MOS：CE2312、XP151、XP161 RFB：Set up so that RFB1/RFB2=（VOUT－VFB）/VFB （VOUT=set-up output voltage）, Please use with RFB1 +RFB2≤2M Ω CFB：Set up that Fzfb=1/(2×π×CFB×RFB1) is within the Adjustments necessary in respect of L,CL. 1、LR9908 CLE9908 Circuits 1:(VIN≥3V) 2、LR9908 CE9908 Circuits 2:(VIN≤3V) 4/8 LESHAN RADIO COMPANY, LTD. ■ Characteristics A. VOUT VS IOUT：（VOUT＝5.5V） B. Efficiency VS IOUT：（VOUT＝5.5V） 5/8 LESHAN RADIO COMPANY, LTD. C. VOUT VS IOUT：（VOUT＝12V） D. Efficiency VS IOUT：（VOUT＝12V） 6/8 LESHAN RADIO COMPANY, LTD. E. VOUT VS IOUT：（VOUT＝18V） F. Efficiency VS IOUT：（VOUT＝18V） 7/8 LESHAN RADIO COMPANY, LTD. Package information ● SOT- 23- 5 ● SOT- 89- 5 8/8