MP3202 MPS | Alldatasheet

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Technical content

1.3A Fixed Frequency White LED Driver MP3202 Rev. 0.91 www.MonolithicPower.com 1 9/21/2007 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2007 MPS. All Rights Reserved. The Future of Analog IC Technology

DESCRIPTION

The MP3202 is a step-up converter designed for driving up to 39 white LEDs (13 strings of 3 LEDs each) from a 5V system rail. The MP3202 uses a current mode, fixed frequency architecture to regulate the LED current, which is measured through an external current sense resistor. Its low 104mV feedback voltage reduces power loss and improves efficiency. Th e OV pin monitors the output voltage and turns off the converter if an over-voltage condition is present due to an open circuit condition. The MP3202 includes under-voltage lockout, current limiting and thermal overload protection preventing damage in the event of an output overload. The MP3202 is available in small 6-pin TSOT23 or 8-pin QFN (2mm x 2mm) packages.

FEATURES

  • 2.5V to 6V Input Voltage Range
  • On Board Power MOSFET
  • Drives up to 39 White LEDs at 5V Input
  • Up to 92% Efficiency
  • Over 1MHz Fixed Switching Frequency
  • Open Load Shutdown
  • Low 104mV Feedback Voltage
  • Soft-Start/PWM Dimming
  • UVLO, Thermal Shutdown
  • Internal 1.3A Current Limit
  • Available in TSOT23-6 and QFN8 Packages

APPLICATIONS

  • Cell Phones
  • Handheld Computers and PDAs
  • Digital Still Cameras
  • Small LCD Displays “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION MP3202 VIN 4.5V - 6V EN

13 Strings

EFFICIENCY (%) INPUT VOLTAGE (V) Efficiency vs Input Voltage IOUT=180mA IOUT=100mA

MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER MP3202 Rev. 0.91 www.MonolithicPower.com 2 9/21/2007 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2007 MPS. All Rights Reserved. PACKAGE REFERENCE Part Number* Package Temperature MP3202DJ TSOT23-6 –40°C to +85°C * For Tape & Reel, add suffix –Z (eg. MP3202DJ–Z) For RoHS compliant packaging, add suffix –LF (eg. MP3202DJ–LF–Z) ABSOLUTE MAXIMUM RATINGS (1) Recommended Operating Conditions (2) Part Number Package Temperature MP3202DG QFN8 (2mm x 2mm) –40°C to +85°C For Tape & Reel, add suffix –Z (eg. MP3202DG–Z) For RoHS compliant packaging, add suffix –LF (eg. MP3202DG–LF–Z) Thermal Resistance (3) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The device is not guaranteed to function outside of its operating conditions. 3) Measured on approximately 1” square of 1 oz copper.

ELECTRICAL CHARACTERISTICS

VIN = VEN = 5V, TA = +25°C, unless otherwise noted. Parameters Symbol Condition Min Typ Max Units Operating Input Voltage V IN 2.5 6 V Supply Current (Shutdown) V EN = 0V 0.1 1 µA Supply Current (Quiescent) V FB = 0.15V 690 750 µA Switching Frequency f SW 1.0 1.3 1.5 MHz Maximum Duty Cycle V FB = 0V 85 92 % Under Voltage Lockout IN Under Voltage Lockout UVLO V IN Rising 2.25 2.45 V Under Voltage Lockout Hysteresis 92 mV Open Lamp Shutdown Threshold VOV V OV Rising 28 V SW GND FB IN OV EN TOP VIEW TOP VIEW GND IN OV EN SW NC FB GND

MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER MP3202 Rev. 0.91 www.MonolithicPower.com 3 9/21/2007 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2007 MPS. All Rights Reserved. ELECTRICAL CHARACTERISTICS (continued) VIN = VEN = 5V, TA = +25°C, unless otherwise noted. Parameters Symbol Condition Min Typ Max Units Enable EN Threshold V EN Rising, VIN = 5V 1.0 1.35 1.6 V EN Threshold V EN Rising, VIN = 2.5V 0.8 V EN Hysteresis 90 mV EN Input Bias Current V EN = 0V, 5V 1 µA Feedback FB Voltage 94 104 114 mV FB Input Bias Current V FB = 0.1V –600 –300 nA Output Switch SW On-Resistance (4) R ON 0.5 Ω SW Current Limit (4) Duty Cycle = 60% 1.33 A Thermal Shutdown (4) 160 °C Notes: 4) Guaranteed by design. PIN FUNCTIONS TSOT23-6 Pin # QFN8 Pin # Name Description 1 8 SW Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to SW. SW can swing between GND and 25V. 2 1, 5 GND Ground. 3 6 FB Feedback Input. The MP3202 regulates the voltage across the current sense resistor between FB and GND. Connect a current sense resistor from the bottom of the LED string to GND. Connect the bottom of the LED string to FB. The regulation voltage is 104mV. 4 4 EN Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns it off. When not used, connect EN to the input source for automatic startup. The EN pin cannot be left floating. 5 3 OV Over Voltage Input. OV measures the output voltage for open circuit protection. Connect OV to the output at the top of the LED string. 6 2 IN Input Supply Pin. Must be locally bypassed. 7 NC No Connect.

MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER MP3202 Rev. 0.91 www.MonolithicPower.com 4 9/21/2007 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2007 MPS. All Rights Reserved. OPERATION The MP3202 uses a constant frequency, peak current mode boost regulator architecture to regulate the strings of white LEDs. Refer to the block diagram in Figure 1 for details. At the start of each oscillator cycle the FET is turned on through the control circuitry. To prevent sub-harmonic oscillations at duty cycles greater than 50%, a stabilizing ramp is added to the output of the current sense amplifier and the result is fed into the positive input of the PWM comparator. When this voltage equals the output voltage of the error amplifier the power FET is turned off. The voltage at the output of the error amplifier is an amplified version of the difference between the 104mV reference voltage and the feedback voltage. In this way the peak current level keeps the output in regulation. If the feedback voltage starts to drop, the output of the error amplifier increases. This results in more current flowing through the power FET, thus increasing the power delivered to the output. PWM COMPARATOR AMPLIFIER CONTROL LOGIC CURRENT SENSE AMPLIFIER SWM1 GND FB 1.3MHz OSC 104mV Figure 1—Functional Block Diagram

MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER MP3202 Rev. 0.91 www.MonolithicPower.com 5 9/21/2007 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2007 MPS. All Rights Reserved.

APPLICATION INFORMATION

9 Strings

Figure 2—Circuit for Driving 27 WLEDs A typical application circuit is provided in Figure 2. The 27 white LEDs can be driven from a voltage supply range of 4V to 6V at a total output current of 180mA. A 2.2µF output capacitor is sufficient for most applications but up to 1µF may be used. A 10µH inductor with low DCR (inductor resistance) is recommended to improve efficiency. A 4.7µF ceramic capacitor is recommended for the input capacitance in the real system. Schottky diodes with fast recovery and a low forward voltage are recommended. Schottky diodes with a 500mA rating are sufficient for the MP3202. The switching characteristics during normal operation can be seen in Figure 3. The MP3202 has internal soft-start to limit the amount of current through the IN pin at startup and to also limit the amount of overshoot on the output. The current limit is increased by a fourth every 40µs giving a total soft-start time of 120µs. VSW 5V/div. VOUT AC 200mV/div. IL 500mA/div. 400ns/div. Steady State Operation VIN = 5V, 27 LEDS, 180mA Figure 3—Steady State Operation Figure 4 shows the startup behavior of the MP3202. The ramped voltage added to the current sense amplifier reduces the current output as the duty cycle increases. As more LEDs are added, the output voltage rises but the current that can be delivered to the load is reduced as well.

MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER MP3202 Rev. 0.91 www.MonolithicPower.com 8 9/21/2007 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2007 MPS. All Rights Reserved.

PACKAGE INFORMATION

0.30 0.50 SEATING PLANE

0.95 BSC

0.84 0.90 1.00 MAX 0.00 0.10 TOP VIEW FRONT VIEW SIDE VIEW RECOMMENDED LAND PATTERN 2.80 3.00 1.50 1.70 2.60 3.00 1 3 0.09 0.20 NOTE: 1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSION OR GATE BURR. 3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. 4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.10 MILLIMETERS MAX. 5) DRAWING CONFORMS TO JEDEC MO-193, VARIATION AB. 6) DRAWING IS NOT TO SCALE. 7) PIN 1 IS LOWER LEFT PIN WHEN READING TOP MARK FROM LEFT TO RIGHT, (SEE EXAMPLE TOP MARK) 0.30 0.500o-8o

0.25 BSC

2.60 TYP 1.20 TYP 0.95 BSC 0.60 TYP SEE DETAIL "A" DETAIL A AAAAPIN 1 See Note 7 EXAMPLE TOP MARK

MP3202 – 1.3A FIXED FREQUENCY WHITE LED DRIVER NOTICE: The information in this document is subject to change wi thout notice. Users should warra nt and guarantee that third party Intellectual Property rights are not infringed upon w hen integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP3202 Rev. 0.91 www.MonolithicPower.com 9 9/21/2007 MPS Proprietary Information. Unaut horized Photocopy and Duplication Prohibited. © 2007 MPS. All Rights Reserved. QFN8 (2mm x 2mm) TOP VIEW BOTTOM VIEW 1.90 2.10 0.45 0.65 1.90 2.10 1.05 1.25 0.50 BSC 0.18 0.30 PIN 1 ID MARKING 0.60 0.50 0.25 RECOMMENDED LAND PATTERN

1.90 NOTE:

1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH. 3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX. 4) DRAWING CONFORMS TO JEDEC MO-229, VARIATION VCCD-3. 5) DRAWING IS NOT TO SCALE. PIN 1 ID SEE DETAIL A 0.70 PIN 1 ID OPTION A R0.20 TYP. PIN 1 ID OPTION B R0.20 TYP.DETAIL A 0.25 0.45PIN 1 ID INDEX AREA SIDE VIEW 0.00 0.05 0.80 1.00

0.20 REF

1.20