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ML0308A Dataheets PDF



Part Number ML0308A
Manufacturers Minilogic Device
Logo Minilogic Device
Description White LED Driver and Step-up DC/DC Converter
Datasheet ML0308A DatasheetML0308A Datasheet (PDF)

ML0308 Preliminary ______________________________________________________________________________________________________ ML0308A/B - Tiny Package, High Efficiency, White LED Driver and Step-up DC/DC Converter FEATURES 1.2MHz Switching Frequency Furnishes the Use of Tiny Surface Mount Components High Output Voltage: Up To 16V Automatic Softstart Drives Up To Four White LEDs From 3.6V Supply APPLICATIONS LCD Bias Handheld Computers Battery Backup Digital Cameras TYPICAL APPLICATIONS DESCRIPTION .

  ML0308A   ML0308A


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ML0308 Preliminary ______________________________________________________________________________________________________ ML0308A/B - Tiny Package, High Efficiency, White LED Driver and Step-up DC/DC Converter FEATURES 1.2MHz Switching Frequency Furnishes the Use of Tiny Surface Mount Components High Output Voltage: Up To 16V Automatic Softstart Drives Up To Four White LEDs From 3.6V Supply APPLICATIONS LCD Bias Handheld Computers Battery Backup Digital Cameras TYPICAL APPLICATIONS DESCRIPTION The ML0308 are high efficiency, white LED driver and step-up DC/DC converters in a tiny SOT23 5-lead package. The ML0308 switches at 1.2MHz. High switching frequency permits the use of tiny, low profile inductors and capacitor to minimize footprint and cost in space-conscious portable applications. The 18V switch allows high output voltage up to 16V to be easily generated in a simple boost topology avoiding the use of costly transformers. www.DataSheet.net/ Figure 1: One-cell Li-ion to 15V Converter and White LED Driver 1/9 Rev. B, July 2005 Datasheet pdf - http://www.DataSheet4U.co.kr/ ML0308 Preliminary ______________________________________________________________________________________________________ ABSOLUTE MAXIMUM RATINGS VIN, FB, CE voltage LX Voltage Junction Temperature Operating Temperature (Note 2) PACKAGE/ORDER INFORMATION ORDER PART NUMBER ML0308AMRG ML0308BMRG PART MARKING 6.0V 18.0V 125°C -30°C to 85°C -40°C to 150°C 300°C Storage Temperature Lead Temperature (soldering 10 seconds) L30C (ML0308AMRG) L36A (ML0308BMRG) ELECTRICAL CHARACTERISTICS The “X” denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 3.0V, VCE = 3.0V unless otherwise noted. PARAMETER Input Voltage Quiescent Current CONDITIONS MIN 2.7 TYP MAX 5.5 UNITS V uA uA mV V uA Ω Non-switching VCE = 0V www.DataSheet.net/ 100 150 0.1 Feedback Voltage ML0308A ML0308B X X 186 1.205 198 1.230 0.1 210 1.255 1.0 Lx Leakage Current Lx ON Resistance Lx Current Limit Lx Voltage Limit (Note 3) Switching Frequency Duty Ratio CE Pin Input High Voltage CE Pin Input LOW Voltage VCE = 0V , VLX = 5.5V VIN = 3.0V, IDS=100mA 180 16.5 0.9 X 72 1.5 1.2 75 250 17.5 1.5 78 mA V MHz % V 0.3 V Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The ML0308 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: If Lx pin exceeds the voltage limit, the ML0308 will stop switching for about 40us. 2/9 Rev. B, July 2005 Datasheet pdf - http://www.DataSheet4U.co.kr/ ML0308 Preliminary ______________________________________________________________________________________________________ PIN FUNCTION DESCRIPTION Pin Description LX Switch Pin. This is the drain of the internal power MOSFET. Minimize the metal trace area (Pin 1) connected to this pin to minimize EMI. GND (Pin 2) FB Feedback Pin. Set the output voltage by selecting values for R1 and R2: (Pin 3) R1 + R 2 R1 + R 2 VOUT = × 0.198V (ML0308A) or VOUT = × 1.23V (ML0308B) R2 R2 Ground. Tie this pin directly to the local ground plane. CE This pin is the chip-enable Pin. Ground this pin to shutdown the chip. Apply a clock with (Pin 4) different duty ratio to control brightness of the LEDs. VIN The external voltage supply is connected to this pin. A high quality reservoir capacitor must (Pin 5) be connected across pin 5 and pin 2 (ground) to achieve the specified output voltage parameters. A 4.7uF/6.3 V, low ESR capacitor must be connected as close as possible across pin 5 and pin 2 (ground). www.DataSheet.net/ BLOCK DIAGRAM – ML0308A 3/9 Rev. B, July 2005 Datasheet pdf - http://www.DataSheet4U.co.kr/ ML0308 Preliminary ______________________________________________________________________________________________________ BLOCK DIAGRAM – ML0308B Figure 2: Internal Block Diagram of ML0308B www.DataSheet.net/ OPERATION The ML0308 uses a pulse-skipping PFM, current mode control scheme to provide excellent line and load regulation. Its operation can be best explained with reference to figure 2 and figure 1. The oscillator generates a clock of 1.2MHz with 75% duty ratio for the PFM controller. When CE pin goes HIGH, the power MOSFET switches at 1.2 MHz to charge the inductor and boost the output voltage to the target level specified by R1 and R2. The output voltage is set as follow: VOUT = R1 + R 2 × 1.23V (ML0308B) R2 limit, comparator A3 will toggle and the control circuit will turn off the MOSFET immediately. So the inductor current is limited. Therefore, soft-start is achieved and potential hazards like current and voltage overshoot are avoided. When output voltage reaches and rises over the regulation point, amplifier A2 will amplify the error. The chip will adjust i.


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