MP3304ADD-LF-P

MP3304 The Future of Analog IC Technology 36V, 1.3A, Step-up White LED Driver with High Frequency True PWM Dimming DESCRIPTION FEATURES The MP3304 is a monolithic step-up converter designed for driving arrays of WLEDs from 5V input or a single cell Lithium Ion battery. The MP3304 uses current mode, fixed frequency architecture to regulate the LED current, which is measured through an external current sense resistor. Its low 200mV feedback voltage reduces power loss and improves efficiency. • • • • Internal Power MOSFET Drives up to 10 Series White LEDs Up to 88% Efficiency PWM Dimming Frequency from 250Hz to 50kHz 2.2MHz Fixed Switching Frequency Open Load Shutdown Low 200mV Feedback Voltage UVLO, Thermal Shutdown Internal 1.3A Current Limit Available in 2x3mm QFN8 Package • • • • • • The MP3304 features up to 50kHz true PWM dimming, which allows the flexible control of the backlighting luminance under wide range of the ambient brightness, and also avoids the possibility of PWM dimming audible noise. APPLICATIONS • • • • • The MP3304 is turned off if an over-voltage condition is present due to an open circuit condition. MP3304 also includes under-voltage lockout, current limiting and thermal overload protection preventing damage in the event of an output overload. LCD Panels Digital Picture Frames Handheld Computers and PDAs Digital Still Cameras Small LCD Displays “Monolithic Power Systems”, “MPS”, and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. The MP3304 is available in small 8-pin QFN 2x3mm package. TYPICAL APPLICATION VIN vs. Efficiency C1 IN Enable/ Dimming Control EN SW MP3304 GND ISET LED RSET String 1 ... String 10 LED1 LED28 LED2 LED29 LED3 LED30 100 C2 EFFICIENCY (%) D L VIN 5V 90 80 70 60 50 3 3.5 4 4.5 5 5.5 6 6.5 VIN (V) MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 1 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING ORDERING INFORMATION Package Top Marking Free Air Temperature (TA) QFN8(2x 3mm) 5Q –40°C to +85°C MP3304BDD** 38V 26V QFN8(2x 3mm) 6R –40°C to +85°C MP3304CDD 20V QFN8(2x 3mm) 2G –40°C to +85°C Part Number* MP3304ADD** Over Voltage Protection *For Tape & Reel, add suffix –Z (eg. MP3304 x DD-Z). For RoHS compliant packaging, add suffix –LF (eg. MP3304 xDD–LF–Z) **Contact Factory for Availability PACKAGE REFERENCE TOP VIEW SW 1 8 GND PGND 2 7 ISET IN 3 6 LED N/C 4 5 EN EXPOSED PAD CONNECTED TO GND ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance SW Pin, LED Pin..........................–0.5V to +42V All Other Pins ..............................–0.3V to +6.5V Storage Temperature.............. –55°C to +150°C (2) Continuous Power Dissipation (TA = +25°C) …………………………………………………1.9W QFN8 2x3mm..........................65 ...... 13 ... °C/W Recommended Operating Conditions (3) IN Supply Voltage .................................3V to 6V SW Pin MP3304ADD ................................... VIN to +36V MP3304BDD .................................... VIN to +24V MP3304CDD.................................... VIN to +18V Operating Junct. Temp (TJ)..... –40°C to +125°C MP3304 Rev. 0.91 4/19/2010 (4) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX)TA) /θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device is not guaranteed to function outside of its operating conditions. 4) Measured on JESD51-7, 4-layer PCB. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 2 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING ELECTRICAL CHARACTERISTICS VIN = VEN = 5V, TA = +25°C, unless otherwise noted. Parameters Symbol Operating Input Voltage Supply Current (Shutdown) Supply Current (Quiescent) Switching Frequency Maximum Duty Cycle Under Voltage Lockout IN Under Voltage Lockout Under Voltage Lockout Hysteresis Open Lamp Shutdown Threshold VIN VEN = 0V VISET=0.3V VUVLO VIN Rising VEN_LOW VEN_HIGH Min Typ Max Units 1 690 2.2 6 2 850 2.7 V µA µA MHz % 2.25 2.45 V 2.5 IIN_SD IIN_QS FSW DMAX VOVP Enable EN OFF Threshold EN ON Threshold Disable Timer Feedback ISET Voltage ISET Input Bias Current Output Switch SW On-Resistance SW Current Limit Condition VISET = 0V 1.7 90 VOV Rising, MP3304ADD VOV Rising, MP3304BDD VOV Rising, MP3304CDD VEN Falling VEN Rising 92 mV 38 26 20 V V V 0.4 1.8 5 VISET VEN > 2V VISET = 0.2V 185 -600 215 mV nA 0.4 1.33 Ω A Thermal Shutdown 150 °C LED Switch(M2, refer block diagram) On Resistance 0.8 Ω MP3304 Rev. 0.91 4/19/2010 RON 200 -300 V V ms Duty Cycle = 60% www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 3 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING PIN FUNCTIONS Pin # Name 1 SW 2 PGND 3 IN 4 N/C No Connect. 5 EN ON/OFF Control and Dimming Command Input. Holding EN pin low for more than 5ms will turn the part off. To use PWM dimming, add a 250Hz to 50KHz square wave signal to this pin. 6 LED LED Current Input. This pin is the open-drain output of an internal dimming control switch. Connect the LED cathode to this pin. 7 ISET LED Current Set. This pin is the source output of an internal dimming control switch. The MP3304 regulates the voltage across the current setting resistor. Tie a current setting resistor from this pin to ground. The regulation voltage is 200mV. 8 Pin Function 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 36V (MP3304A), 24V (MP3304B) or 18V (MP3304C). Power Ground. Input Supply Pin. Must be locally bypassed. GND, Ground. Connect Exposed Pad to GND plane for optimal thermal performance. Exposed Pad MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 4 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING TYPICAL PERFORMANCE CHARACTERISTICS VIN = 5V, ILED = 200mA, 3WLEDs 10Strings, unless otherwise noted. VIN vs. Efficiency PWM Dimming Duty vs. WLED Current 100 Steady State Operation 200 WLED CURRENT (MA) EFFICIENCY (%) 180 90 80 70 60 160 SW 5V/div FB 50mV/div 50kHz 140 20kHz 120 100 VOUT (AC) 200mV/div 80 60 40 250Hz 1kHz 20 0 0 50 3 3.5 4 4.5 5 5.5 6 6.5 VIN (V) 20 40 60 80 IINDUCTOR 500mA/div 400ns/div 100 PWM DIMMING DUTY (%) Enable Startup Enable Shutdown PWM Dimming fPWM=50kHz, DPWM=50% SW 10V/div SW 10V/div EN 2V/div EN 2V/div VOUT 2V/div ILED 100mA/div VOUT 2V/div ILED 100mA/div SW 10V/div PWM 2V/div VOUT 10V/div ILED 100mA/div Open Load Protection SW 10V/div ILED 100mA/div VOUT 5V/div MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 5 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING OPERATION The MP3304 uses a constant frequency, peak current mode boost regulator architecture to regulate the series string of white LEDs. The operation of the MP3304 can be understood by referring to the block diagram of Figure 1. The voltage at the output of the error amplifier is an amplified version of the difference between the 200mV reference voltage and the feedback voltage. In this way the peak current level keeps the output in regulation. 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 percent, 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. 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. ISET LED 200mV + + CONTROL LOGIC M1 SW AMPLIFIER PWM COMPARATOR M2 ISET + ENABLE & DIMMING CONTROL EN Enable + - GND CURRENT SENSE AMPLIFIER 2.2MHz OSC Figure 1—Functional Block Diagram MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 6 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING APPLICATION INFORMATION L D1 VIN 5V MBR0520 IN Enable/ Dimming Control EN SW MP3304 GND ISET LED Figure 2—Circuit for Driving 10 Strings of 3 WLEDs A typical application circuit can be seen in Figure 2. The 10 strings of 3 white LEDs can be driven from a 5V voltage at an output current of 200mA. A 2.2µF output capacitor is sufficient for most applications. A 2.2µH inductor with low DCR (Inductor DC resistance) is recommended to improve efficiency. A 10µF ceramic capacitor is recommended for the input capacitance in the real system. Schottky diodes have fast recovery and a low forward voltage are recommended. Schottky diodes rated with 500mA are sufficient for the MP3304. The MP3304 has internal softstart to limit the amount of current through VIN at startup and to also limit the amount of overshoot on the output. The ramped voltage that is 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. Setting the LED Current The LED current is controlled by the current setting resistor, R1. The current through the LEDs is given by: ILED = 200mV/R1. Table 1 shows the selection of resistors for a given LED current. MP3304 Rev. 0.91 4/19/2010 Table 1—ILED vs. R1 RSET ILED (mA) 1 5 10 20 60 180 200 R1 (Ω) 200 40 20 10 3.33 1.11 1 PWM Dimming Apply a 250Hz to 50kHz square waveform to the EN pin to implement PWM dimming of the LEDs. The minimum recommended amplitude of the PWM signal is 2V. Open Load Protection Open Load protection will shut off the MP3304 if the output voltage goes too high. In some cases an LED may fail, this will result in the feedback voltage always being zero. The part will run at maximum duty cycle boosting the output voltage higher and higher. If the output voltage ever exceeds the open load protection threshold voltage, the MP3304 will shut down. The part will not switch again until the power is recycled. For MP3304A, MP3304B, and MP3304C, the open load protection threshold voltages are 38V, 26V, and 20V respectively. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 7 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING Layout Considerations Careful attention must be paid to the PCB board layout and components placement. Proper layout of the high frequency switching path is critical to prevent noise and electromagnetic interference problems. The loop of MP3304 SW to GND pin, output diode, and output capacitor is flowing with high frequency ripple current, it must be as short as possible. The IN pin of the IC must be locally bypassed. A RC filter is highly recommended for eliminating the noise on IN pin. It could be implemented as shown in Figure 3. Input SW IN MP3304 GND Figure 3—Input Bias Filtering MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 8 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING TYPICAL APPLICATION CIRCUITS D1 B0530 String L1 2uH VIN 5V C1 10uF IN Enable/ Dimming Control EN SW LED1 LED28 LED2 LED29 LED3 MP3304C GND ISET 1 ... String 10 LED30 C2 2.2uF LED Figure 4 — Driving 30 WLEDs (3 WLEDs in Series and 10 Strings Paralleled) with 5V Input Voltage D1 B0540 L1 VIN 5V C1 4.7uF 16V C2 4.7uF 16V 4.7uH JP1 R1 100 Bias EN GND C3 0.1uF R2 0 C4 NS 3 5 U1 IN 1 SW C5 0.47uF 50V EN MP3304A LED 8 GND ISET PGND 2 6 LED+ LED- 7 R3 3.32 1% R4 NS Figure 5 — Driving 27 WLEDs (9 WLEDs in Series and 3 Strings Paralleled) with 5V Input Voltage MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 9 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING TYPICAL APPLICATION CIRCUITS (continued) D1 B0540 L1 VIN 3.3V -18V C1 10uF 25V 10uH C2 330nF 50V 7.5 Optional Bias Circuit D2 5.6V ZENER C3 0.1uF 50V 5 EN 3 LED+ 1 IN SW LED6 MP3304A LED EN GND GND PGND 8 7 ISET 2 Figure 6 — Driving 27 WLEDs (9 WLEDs in Series and 3 Strings Paralleled) with 3.3V-18V Input Voltage In order to improve the MOSFET on-resistance at low input voltage and make the chip compatible for high input voltage, the additional bias circuit should be used. D1 L1 VIN 4.5V-18V 10uH C1 10uF 25V B0540 C4 330nF 50V Q2 2N3904 D2 5.6V ZENER C3 0.1uF 25V 3 1 IN SW LED+ LED- Required Bias Circuit for High Input Voltage EN 5 8 GND MP3304A EN LED GND PGND ISET 6 7 2 Figure 7 — Wide Input Voltage Step-up Converter for 27 WLEDs ( 9 WLEDs in Series and 3 Strings Paralleled ) MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 10 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING TYPICAL APPLICATION CIRCUITS (continued) L1 VIN 5V D1 C1 16V B0540 R2 LED1 LED2 3 C2 IN 16V EN GND 5 1 LED3 SW LED4 LED5 MP3304A EN 8 LED GND PGND ISET 2 7 6 C3 330nF LED6 LED7 R1 1% LED8 LED9 LED10 Figure 8 — Driving 10 WLEDs in Series with 5V Input Voltage MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 11 MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING PACKAGE INFORMATION QFN8 (2mm x 3mm) 2.90 3.10 PIN 1 ID MARKING 0.30 0.50 0.18 0.30 1.90 2.10 PIN 1 ID INDEX AREA 1.65 1.85 8 PIN 1 ID SEE DETAIL A 1 1.50 1.70 0.50 BSC 4 5 TOP VIEW BOTTOM VIEW PIN 1 ID OPTION A 0.30x45” TYP. 0.80 1.00 PIN 1 ID OPTION B R0.20 TYP. 0.20 REF 0.00 0.05 SIDE VIEW DETAIL A 2.90 0.70 NOTE: 1.70 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 VCED-2. 5) DRAWING IS NOT TO SCALE. 0.25 1.60 0.50 RECOMMENDED LAND PATTERN NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP3304 Rev. 0.91 4/19/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 12