MP3309 2.7V-5.5V Input, 35V Output White LED Driver The Future of Analog IC Technology FEATURES DESCRIPTION The MP3309 is a WLED step-up converter for 2.7V-to-5.5V input that uses peak-current mode to regulate the LED current sensed through an external, low-side resistor. The 200mV feedback voltage and synchronous rectification reduces power loss and reduces PCB space requirements. The MP3309 features a programmable switching frequency to optimize efficiency. It supports both analog and PWM dimming. APPLICATIONS In addition, the MP3309 has LED open protection, cycle-by-cycle current limit protection, Under voltage protection and thermal shutdown protection . 2.7V-to-5.5V Input Voltage Analog and PWM Dimming Programmable Switching Frequency Low 200mV Feedback Voltage with ±1% Internal Soft Start UVLO, Thermal Shutdown, OCP Available in a 1.4mm ×1.8mm QFN-10 package Feature Phones and Smart Phones Tablets <10inchVideo Displays All MPS parts are lead-free, halogen free, and adhere to the RoHS directive. For MPS green status, please visit MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION Typical Application Circuit MP3309 Rev. 1.02 5/21/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 1 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER ORDERING INFORMATION Part Number MP3309GQG* Package QFN-10 (1.4mm×1.8mm) Top Marking BM * For Tape & Reel, add suffix –Z (e.g. MP3309GQG–Z); PACKAGE REFERENCE TOP VIEW QFN-10 (1.4mm×1.8mm) ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance VIN ...................................................-0.3V to +6V VSW, VOUT…………………………..…-1V to +40V VBST ......................................... -0.3V to VSW +6V All Other Pins ................................. –0.3V to +6V Junction Temperature ...............................150°C Lead Temperature ....................................260°C (2) Continuous Power Dissipation (TA = 25°C) ................... ................... ........................0.892W QFN-10 (1.4mm×1.8mm) ..... 140 ...... 30 °C/W Recommended Operating Conditions (3) Supply Voltage VIN .......................... 2.7V to 5.5V Operating Junction Temp. (TJ). -40°C to +125°C MP3309 Rev. 1.02 5/21/2018 (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. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 2 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER ELECTRICAL CHARACTERISTICS VIN =3.6V, VEN = VIN, TA = 25°C, unless otherwise noted. Parameters Symbol Condition Min Typ Max Units 5.5 V STEP-UP CONVERTER Operating Input Voltage VIN Supply Current (Quiescent) IQ Supply Current (Shutdown) IST Input UVLO Threshold VIN_UVLO 2.7 VIN=3.6V, VEN= VIN, no load with switching VEN=0V, VIN=3.6V EN Bit=0, VIN=3.6V Rising Edge 420 1 Input UVLO Hysteresis EN High Voltage VEN_HIGH VEN Rising EN Low Voltage VEN_LOW VEN Falling Switching Frequency fSW Maximum Duty Cycle DMAX Feedback Regulation Voltage VREF μA 68 2.5 μA μA V 200 mV 1.2 V 0.4 V 740 kHz ROSC= 200kΩ 540 640 Sync Mode, 600kHz 89 93 198 200 202 mV % POWER SWITCH Main Switch On-Resistance RDSON_M VIN=3.6V 0.3 0.5 Ω Sync Switch On-Resistance RDSON_S VIN=3.6V 0.5 0.8 Ω PWMH Input Low Threshold VPWM_LO VPWM Falling PWMH Input High Threshold VPWM_HI VPWM Rising CURRENT DIMMING EN/PWML Shutdown Time tSD 0.4 V 1.2 EN/PWML High to Low 20 V ms PROTECTION OVP Voltage VOVP 33.5 35.5 37.5 V Hysteresis 2.5 ILIM Max Duty Cycle 1.5 A Startup Current Limit ILIM_START Max Duty Cycle 0.8 A Time Step for Half Current Limit TLIM_HALF 5 ms OVP UVLO Threshold VOVP_UV 1.24 V tST 150 °C 25 °C Cycle-Cycle Current Limit Thermal Shutdown Threshold Thermal Shutdown Hysteresis MP3309 Rev. 1.02 5/21/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 3 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS VIN = 3.6V, 8 LEDs, ILED=20mA, L = 10µH, TA = 25°C, unless otherwise noted. 100 95 90 6 LED 600kHz 85 80 8 LED 600kHz 10 LED 600kHz 75 70 65 60 3.0 3.2 VSW 20V/div. VPWML 5V/div. ILED 20mA/div. IL 200mA/div. MP3309 Rev. 1.02 5/21/2018 VSW 10V/div. VPWMH 5V/div. ILED 20mA/div. IL 200mA/div. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 4 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER PIN FUNCTIONS Pin # 1,10 2 3 4 5 6 7 8 9 MP3309 Rev. 1.02 5/21/2018 Name Description Dimming input pin for PWM input analog dimming, >20kHz PWM signal is recommended. Pull 2 pins high together when analog dimming is not used. Input Supply Pin. Provides power for internal power and logic circuits. Must be locally VIN bypassed. PWM Brightness Control/Enable. Apply a PWM signal for PWM dimming. The PWM duty is proportional to the LED current dimming —a lower dimming duty results in a EN/PWML smaller dimming current. For most applications, use a frequency range of 200Hz to 2kHz. A low-level signal longer than 20ms will shutdown the IC. Switching Frequency Set. Connect a resistor between this pin and GND to program RFEQ the converter switching frequency. Do not leave this pin floating. LED Current Feedback. Regulates the voltage across the current sense resistor FB between FB and GND to 200mV. GND Ground. Power Switch Node. Drain of the internal low-side MOSFET. Connect the power SW inductor between SW and VIN pin. For non-synchronous mode, connect a Schottky diode between this pin and VOUT. Output Voltage. Internally connected to the source of the synchronous MOSFET. For VOUT non-synchronous mode, connect a Schottky diode between SW pin and this pin. . Booststrap. Connect a capacitor between SW and BST pin to provide the BST synchronous MOSFET gate driver. PWMH www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 5 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER BG&Logic Control Unit EN Detect EN/PWML M2 Regulator OSC VREF&DPWM PWM Control RAMP M1 DPWM VREF EA PWM Comparator OSC Figure 1: Functional Block Diagram MP3309 Rev. 1.02 5/21/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 6 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER OPERATION The MP3309 uses the peak current mode control architecture to regulate the current flowing through the white LEDs string. The operation of the MP3309 can be understood by referring to the function block diagram. At the start of each oscillator cycle, the control circuit turns on the low-side MOSFET (LS-FET, M1). A stabilizing ramp added to the output of the current-sense amplifier, which then feeds into the positive input of the PWM comparator, prevents sub-harmonic oscillations at duty cycles greater than 50%. When the input to the PWM comparator equals the output voltage of the error amplifier. M1 turns off. Then the inductor current flows through the synchronous power MOSFET, which forces the inductor current to decrease. The voltage at the output of the error amplifier is the amplified difference between the 200mV reference voltage and the feedback voltage. If the feedback voltage starts to drop, the output of the error amplifier increases, increasing the current flowing through the M1, thus increasing the power to the inductor and output power. This method accurately regulates the LED current. System Startup When enabled, the MP3309 checks safety limits, including UVLO and over-temperature protection (OTP), over-current protection after passing the OVP test. If all the protection tests pass, the chip then starts boosting the step-up converter with an internal soft-start. When enable on, since for soft-start, the current limit drops to 0.8A during startup to prevent a large inrush current. This low-current-limit time lasts for 5ms after the IC is enabled. Dimming Control The MP3309 provides two dimming methods: PWM and analog dimming mode. For PWM dimming, apply a PWM signal to the EN/PWML pin. The LED current is then segmented as per the PWM signal and the average LED current equals: Iset D dim .Where Ddim is the PWM duty cycle, and Iset is the LED current amplitude. When PWM signal is high, MP3309 Rev. 1.02 5/21/2018 the converter operates in normal mode. Conversely, when the PWM amplitude is low, the converter stops switching. Make sure that the PWM-signal low-level time is less than 20ms or the IC will shutdown. Use a 200Hz-to2kHz PWM-dimming frequency for most dimming ratio requests. For analog dimming, set the LED current amplitude through an external PWM signal. For MP3309, implement analog dimming by the PWMH pins and apply a PWM signal. An internal RC fliter filters the PWM signal. The LED current amplitude equals Iset×Ddim, where Ddim is the PWM duty cycle and Iset is the LED current amplitude. Use a>20kHzPWM signal to improve filtering performance. Open-String Protection The MP3309 monitors the VOUT pin for openstring protection. If the LED string is open, the feedback voltage is lower than the reference voltage. The COMP then rises and charges the output capacitor until the VOUT voltage reaches the protection point, VOVP. The OVP point of MP3309 is 35.5V. Typically, the hysteresis is 2.5V. The IC stops switching when VOUT reaches the OVP threshold, the IC resumes function when VOUT drops below the threshold. Input Under-Voltage Protection When VIN exceeds 2.5V, the converter starts to charge the internal reference and provides power to the internal control circuitry. There is UVLO hysteresis, approximately 200mV, as VIN falls. The IC shuts down when the input voltage drops below 2.3V. Thermal-Shutdown Protection Thermal shutdown prevents the IC from operating at exceedingly high temperatures. When the die temperature exceeds the upper threshold (TST), the IC shutdowns and resumes normal operation when the die temperature drops below lower threshold. Typically, the hysteresis is 25°C. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 7 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER APPLICATION INFORMATION Selecting the Switching Frequency The switching frequency of the step-up converter can be programmed from 300kHz to 1.2MHz. A resistor on the OSC pin sets the internal oscillator frequency for the step-up converter as per the equation below: fSW (kHz) 120000 ROSC (k ) For instance, if ROSC=200kΩ, the switching frequency is to 600kHz. Setting the LED Current Set the LED current through the current-setting resistor on the FB pin. ILED (mA) VREF (V) 1000 RFB ( ) For instance, if VREF=200mV, and RFB=10Ω, the LED current is 20mA. Do not leave the FB pin floating. Selecting the Input Capacitor The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. The input capacitor impedance at the switching frequency should be less than the input source impedance to prevent the high-frequency switching current from passing through to the input. Use ceramic capacitors with X5R or X7R dielectrics for their low ESR and small temperature coefficients. For most applications, use a 2.2µF-to-10μF ceramic capacitor. Selecting the Inductor The MP3309 requires an inductor to boost its output voltage. A larger value inductor results in less ripple current, lowering both the peakinductor current and the stress on the internal N-channel MOSFET. However, the larger inductor is physically larger, has a higher series resistance, and a lower saturation current. Choose an inductor that does not saturate under the worst-case load conditions. Select the minimum inductor value to ensure that the boost converter works in continuous-conduction mode with high efficiency and good EMI performance. MP3309 Rev. 1.02 5/21/2018 Calculate the required inductance value using the equation: η VOUT D (1 D)2 L 2 fSW ILOAD V D 1 IN VOUT Where VIN and VOUT are the input and output voltages, fSW is the switching frequency, ILOAD is the LED load current, and η is the efficiency. The switching current for peak-current mode. To avoid hitting the current limit, the worst-case inductor peak current should be less than 80% of the current limit, ILIM. Selecting the Output Capacitor The output capacitor keeps the output voltage ripple small and ensures feedback loop stability. The output capacitor impedance must be low at the switching frequency. Ceramic capacitors with X7R dielectrics are recommended for their low ESR characteristics. Selection must also account for the capacitance’s dependence on the voltage rating; with a DC bias voltage, the capacitor can lose as much as 50% of its capacitance at its rated voltage rating. Leave a sufficient voltage rating margin when select the component. Too-low or too-high capacitance will cause loop instability. For most applications, select a capacitor in the range of 0.1µF to 1μF. Internal Soft Start When enable on, IL current limit drop to half to prevent inrush during startup. 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 limit electromagnetic interference. The loop consisting of MP3309’s internal low-side MOSFET, synchronous MOSFET or diode, and output capacitor contains a high-frequency ripple current—minimize this loop. Place the input and output capacitor should as to the IC as possible. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 8 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER TYPICAL APPLICATION CIRCUITS Figure 2: Typical Application for Single String 8LEDs Figure 3: Typical Application for 3X3 LED Array MP3309 Rev. 1.02 5/21/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 9 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER L1 22 H R3 VIN C1 4.7 F/10V C2 10nF SW BST GND IN R4 2k PWMH OUT MP3309 PWMH (pin 1) PWMH (pin 10) EN/PWML C3 0.47 F /50V 7*LEDs PWM FREQ FB R2 100k GND R1 10 Figure 4: Typical Application for More Noise Robust Test MP3309 Rev. 1.02 5/21/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 10 MP3309 2.7V-5.5V INPUT, 35V OUTPUT, fs-PROGRAMMABLE, WHITE LED DRIVER PACKAGE INFORMATION QFN-10 (1.4mmX1.8mm) NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications. 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. MP3309 Rev. 1.02 5/21/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 11