MP1521_r2.7w ETC

Document overview

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Technical content

Features

ƒ On Board Power MOSFET ƒ Drive 9 White LEDs from 2.7V Input ƒ Drive 15 White LEDs from 5V Input ƒ Up to 90% Efficiency ƒ Over 80mA Output Current Capacity ƒ Open Load Shutdown ƒ Low Current Sensing Feedback Voltage ƒ Up to 3 String Current Sensing Feedback ƒ Analog and Digital PWM Brightness Control ƒ UVLO, Thermal Shutdown ƒ Soft Start ƒ Internal Current Limit ƒ Available in Compact MSOP10 and Tiny 3 mm x 3 mm QFN16 Package ƒ Evaluation Boards Available

Applications

ƒ Handheld Computers, Cell phones, PDAs, Digital and Video Cameras, Small LCD Displays ƒ Li Ion and NiMH Battery Applications Typical Application Circuit (One String of Six (6) LEDs) IN BRT/PWM FB1 OLS SW 10 GND 9 CIN COUT EN REF MP1521 6 5 FB2 FB3 White LEDs BRT/ PWM EN GND OFF ON VIN Efficiency vs LED current, 1 string of 6 Using Toko D62CB 47µH Inductor 100 5 10 15 20 25 LED Current (mA) Efficiency (%) VIN = 5V VIN = 4V VIN = 3V

MP1521 Rev 2.7 10/06/04 www.monolithicpower.com 2 Monolithic Power Systems Absolute Maximum Ratings Supply Voltage (VIN) 28V Switch Voltage to GND -0.5V to 28V V EN, VREF, VBRT, VFB1, VFB2, VFB3 –0.3V to 6V Storage Temperature -55 °C to +150°C Recommended Operating Conditions Supply Voltage (VIN) 2.7V to 25V Operating Temperature -20 °C to +85°C Switch Voltage to GND -0.5V to 25V Package Thermal Characteristics Thermal Resistance, ΘJA (MSOP10) 150°C/W Thermal Resistance, ΘJA (QFN16) 60°C/W Electrical Characteristics (VIN = 5.0V, TA = 25°C unless specified otherwise) Parameters Symbol Condition Min Typ Max Units Supply Current (shutdown) I IN (OFF) V EN<0.4V 1 3 µA Supply Current (quiescent) I IN (ON) V EN >1.5V, VBRT=0V, VFB=0V 550 700 µA Minimum Off Time, normal operation tOFF (NORMAL) VEN >1.5V, VBRT =0.6V VFB =0 400 500 700 nS Minimum Off Time, start-up (Note 1) tOFF (START) VEN >1.5V, VBRT =0.6V, VFB =0V 1.5 2.4 µS UVLO V IN RISING 2.1 2.6 V Under Voltage Lockout V IN FALLING 1.9 2.4 V Enable Threshold 0.8 1.0 2.0 V Hysterisis 60 mV Leakage Current V EN=3V 1 µA Open Load Shutdown Threshold Measured at OLS Pin 26 29 V VOLS=15V 1 µA Leakage Current VOLS=25V 45 70 µA Reference Output Voltage I REF=0A 1.20 1.235 1.27 V Load Regulation IREF=0 to 100µA 2.5 5 mV Line Regulation V IN =3 to 15V, IREF=0A 2.5 5 mV Feedback Comparator Threshold V BRT =1.2V 380 400 420 mV Hysterisis (Note 2) V BRT =1.2V 30 mV FB Input Bias Current V FB=0.2V -150 -50 0 nA PWM Mode Output-Off Threshold 0.18 0.26 V BRT Input Bias V BRT=0.6V -100 -30 0 nA BRT Full Scale Threshold (Note 3) 1.2 V Output Switch Switch On Resistance (Note 2) R ON V IN=5.0V 0.5 0.6 Ω Switch Current Limit 300 400 mA Leakage Current V SW=25V 5 µA Thermal Shutdown (Note 2) 160 °C Notes: 1) First 64 pulses after EN switches high. 2) Guaranteed by design. 3) The output current is off when BRT is driven below the output-off threshold and full-scale when driven above the full-scale threshold. To PWM the output drive BRT above and below these thresholds.