MP24833-AGN-Z

MP24833-A 55V, 3A, White LED Driver The Future of Analog IC Technology DESCRIPTION FEATURES The MP24833-A is a 55V, 3A, white LED driver suitable for step-down, inverting step-up/stepdown, and step-up applications. The MP24833A achieves 3A of output current with excellent load and line regulation over a wide input supply range.           Current mode operation provides a fast transient response and eases loop stabilization. Full protection features include thermal shutdown, cycle-by-cycle peak current limiting, open-string protection, and output short-circuit protection (SCP). The MP24833-A incorporates both DC and PWM dimming into a single control pin. The separate input reference ground pin allows for direct enable and/or dimming control for a positive-to-negative power conversion.      The MP24833-A requires a minimal number of readily available, standard, external components and is available in a SOIC-8 EP package. 3A Maximum Output Current Unique Step-Up/Step-Down Operation (Buck-Boost Mode) Wide 4.5V-to-55V Operating Input Range for Step-Down Applications (Buck Mode) 0.15Ω Internal Power MOSFET Switch Fixed 210kHz Switching Frequency Analog and PWM Dimming 0.2V Reference Voltage 6μA Shutdown Mode No Minimum Number of LEDs Required Stable with Low ESR Output Ceramic Capacitors Cycle-by-Cycle Over-Current Protection (OCP) Thermal Shutdown Protection Open-String Protection Output Short-Circuit Protection (SCP) Available in a SOIC-8 EP Package APPLICATIONS       General LED Illumination LCD Backlight Panels Notebook Computers Automotive Internal Lighting Portable Multimedia Players Portable GPS Devices All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For MPS green status, please visit the MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION 3 CIN EN/DIM 5 ON SW 7 CBST 8 L EN/DIM D OFF DC or PWM Input 6 INGND FB VSS Co LEDs BST ROVP1 VDD ROVP2 1 VIN OVP 4 R FB 2 MP24833-A Rev. 1.02 www.MonolithicPower.com 3/29/2019 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2019 MPS. All Rights Reserved. 1 MP24833-A – 55V, 3A, WHITE LED DRIVER ORDERING INFORMATION Part Number* Package Top Marking MP24833-AGN SOIC-8 EP See Below * For Tape & Reel, add suffix –Z (e.g. MP24833-AGN–Z) TOP MARKING M24833-A: Part number LLLLLLLL: Lot number MPS: MPS prefix Y: Year code WW: Week code PACKAGE REFERENCE SOIC-8 EP MP24833-A Rev. 1.02 www.MonolithicPower.com 3/29/2019 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2019 MPS. All Rights Reserved. 2 MP24833-A – 55V, 3A, WHITE LED DRIVER ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance (4) Supply voltage (VDD - VSS) ............................ 57V VSW - VSS ............................... -0.3V to VIN + 0.3V VBST........................................................ VSW + 6V VEN/DIM - VINGND ................................. -0.3V to +6V VINGND - VSS ...................................... -0.3V to 57V Other pins - VSS ............................... -0.3V to +6V Continuous power dissipation (TA = +25°C) (2) SOIC-8 EP .................................................. 2.5W Junction temperature ................................ 150°C Lead temperature...................................... 260°C Storage temperature .................-65°C to +150°C SOIC-8 EP ............................... 50 ...... 10... °C/W Recommended Operating Conditions (3) 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 produces an excessive die temperature, causing the regulator to go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device function is not guaranteed outside of the recommended operating conditions. 4) Measured on JESD51-7, 4-layer PCB. Supply voltage (VDD - VSS) ............... 4.5V to 55V Maximum junction temp. (TJ).. ............... .+125°C MP24833-A Rev. 1.02 www.MonolithicPower.com 3/29/2019 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2019 MPS. All Rights Reserved. 3 MP24833-A – 55V, 3A, WHITE LED DRIVER ELECTRICAL CHARACTERISTICS VIN = 12V, TJ = -40°C~125°C, all voltages with respect to VSS, unless otherwise noted. Parameters Feedback voltage Feedback current Switch on resistance Switch leakage Current limit Oscillator frequency Foldback frequency Maximum duty cycle Minimum on time (5) Under-voltage lockout threshold rising Under voltage lockout threshold hysteresis EN input current EN off threshold (with respect to INGND) EN on threshold (with respect to INGND) Minimum EN dimming threshold Maximum EN dimming threshold Supply current (quiescent) Supply current (quiescent) at EN off Thermal shutdown (6) Thermal shutdown recovery hysteresis Open LED OV threshold Open LED OV hysteresis Symbol Condition VFB 4.5V  VIN  55V IFB VFB = 0.22V RDS(ON) VEN = 0V, VSW = 0V Min 0.19 -100 150 3 145 fSW VFB = 0V, VOVP = 0V 85 tON 3 IQ Ioff VOVP_th VOVP_hys VEN = 2V VEN falling VEN rising VFB = 0V VFB = 0.2V VEN = 2V, VFB = 1V VEN = 0V Typ 0.2 4.8 210 37 91 100 3.3 200 Max 0.21 100 280 1 275 97 3.6 2.1 0.4 0.57 1.23 2.3 0.67 1.35 0.6 6 150 15 2.43 80 0.6 0.77 1.47 0.8 12 2.6 Units V nA mΩ μA A kHz kHz % ns V mV μA V V V V mA μA °C °C V mV NOTES: 5) Guaranteed by design. 6) Guaranteed by characterization. MP24833-A Rev. 1.02 www.MonolithicPower.com 3/29/2019 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2019 MPS. All Rights Reserved. 4 MP24833-A – 55V, 3A, WHITE LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS MP24833-A Rev. 1.02 www.MonolithicPower.com 3/29/2019 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2019 MPS. All Rights Reserved. 5 MP24833-A – 55V, 3A, WHITE LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS (continued) Performance waveforms are tested on the evaluation board in the Design Example section. VIN = 20V, ILED = 1A, 7WLEDs in series, L = 68µH, TA = 25°C, buck-boost application, unless otherwise noted. 89.5 1000 1000 800 800 88 600 600 87.5 400 400 200 200 89 88.5 87 86.5 86 12 SW-VSS 20V/div. VOUT 20V/div. 14 16 18 20 22 0 0.5 24 VSW 20V/div. 0.9 1.1 1.3 0 0 1.5 VSW 20V/div. VSW 20V/div. VOUT 1V/div. VOUT 1V/div. IL 1A/div. IOUT 500mA/div. IL 1A/div. IOUT 500mA/div. VSW 20V/div. VOUT 20V/div. VSW 20V/div. VOUT 20V/div. IL 1A/div. IL 1A/div. IOUT 500mA/div. ISHORT 500mA/div. IL 1A/div. IOUT 500mA/div. 0.7 0.2 0.4 0.6 0.8 1 VPWM 2V/div. IL 1A/div. IOUT 500mA/div. MP24833-A Rev. 1.02 www.MonolithicPower.com 3/29/2019 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2019 MPS. All Rights Reserved. 6 MP24833-A – 55V, 3A, WHITE LED DRIVER PIN FUNCTIONS Pin # 1 2 3 4 5 6 7 8 Name Description Supply voltage. The MP24833-A operates from a 4.5V-to-55V unregulated input (with respect to VSS). An input capacitor is needed to prevent large voltage spikes from appearing at input. VSS, Power return. VSS is the voltage reference for the regulated output voltage, and requires Exposed extra care during layout. Connect VSS to the lowest potential in the circuit, which is the anode Pad of the Schottky rectifier, typically. The exposed pad is also connected to VSS. Over-voltage protection. Use a voltage divider to program the OVP threshold. When the OVP voltage reaches the shutdown threshold (2.43V), the switch turns off and recovers when the OVP voltage drops to its normal operating range. When the voltage (with respect to VSS) OVP drops below 0.2V, and the FB voltage is below 0.1V, the chip treats this as a short circuit and the operating frequency folds back. Program the OVP voltage from 0.2V to 2.43V for normal operation. LED current feedback input. FB senses the current across the sensing resistor between FB FB and VSS. Connect the current sensing resistor from the bottom of the LED strings to VSS. FB is connected to the bottom of the LED strings. The regulation voltage is 0.2V. On/off control input and dimming command input. A voltage greater than 0.67V turns on the chip. EN/DIM implements both DC and PWM dimming. When the EN/DIM voltage (with respect to INGND) rises from 0.67V to 1.35V, the LED current changes from 0% to 100% of EN/DIM the maximum LED current. To use PWM dimming, apply a 100Hz-to-2kHz square wave signal with an amplitude greater than 1.5V to EN/DIM. For combined analog and PWM dimming, apply a 100Hz-to-2kHz square wave signal with an amplitude from 0.67V to 1.35V. INGND Input ground reference. INGND is the reference for the EN/DIM signal. Bootstrap. Connect a capacitor between SW and BST to form a floating supply for the power BST switch driver. Use a ceramic capacitor 100nF or larger to provide sufficient energy to drive the power switch with this supply voltage. Switch output. SW is the source of the internal MOSFET. Connect SW to the power inductor SW and the cathode of the rectifier diode. VDD MP24833-A Rev. 1.02 www.MonolithicPower.com 3/29/2019 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2019 MPS. All Rights Reserved. 7 MP24833-A – 55V, 3A, WHITE LED DRIVER BLOCK DIAGRAM 2.4V Figure 1: Functional Block Diagram MP24833-A Rev. 1.02 www.MonolithicPower.com 3/29/2019 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2019 MPS. All Rights Reserved. 8 MP24833-A – 55V, 3A, WHITE LED DRIVER OPERATION The MP24833-A is a current-mode regulator. The error amplifier (EA) output voltage is proportional to the peak inductor current. At the beginning of a cycle, the MOSFET is off. The EA output voltage is higher than the current sense amplifier output, and the current comparator’s output is low. The rising edge of the CLK signal sets the RS flip-flop. The CLK frequency is the operating frequency. The flipflop output turns on the MOSFET that connects SW and the inductor to the input supply. The current sense amplifier detects and amplifies the rising inductor current. The PWM comparator compares the output of the EA against the sum of the ramp compensator and the current sense amplifier. When the sum of the current sense amplifier output and the slope compensation signal exceeds the EA output voltage, the RS flip-flop resets, and the MOSFET turns off. The external Schottky rectifier diode (D) conducts the inductor current. If the sum of the current sense amplifier output and the slope compensation signal does not exceed the EA output throughout the cycle, then the falling edge of the CLK resets the flipflop. The output of the EA integrates the voltage difference between the feedback and the 0.2V reference. The EA output increases when the FB voltage is less than 0.2V. Since the EA output voltage is proportional to the peak inductor current, the increase in the EA output voltage also increases the current delivered to the output. Soft Start (SS) When the MP24833-A is enabled and VDD exceeds the UVLO threshold, switching begins. The soft start is not active when VFB - VSS is lower than half of VREF, which is useful for charging the output capacitor quickly. At the same time, the current limit is folded to half. Once VFB - VSS rises up to half of VREF, the soft start begins and forces the internal reference input of the EA to rise up from ⅔ of VREF slowly. The current limit also recovers the normal value. The soft-start function can make the duty cycle extend slowly to limit current overshoot at startup. Open-LED Protection The OVP pin is used for open-LED protection and monitors the output voltage through a voltage divider. If the LED is open, there is no voltage on FB. The duty cycle increases until VOVP - VSS reaches the protection threshold set by the external resistor divider. The top switch turns off until VOVP - VSS decreases sufficiently. Dimming Control The MP24833-A allows for both DC and PWM dimming. When the voltage on EN/DIM (reference to INGND) is less than 0.6V, the chip turns off. For analog dimming, the LED current is dependent linearly on the EN/DIM voltage range between 0.67V and 1.35V, from 0% to 100%. An EN/DIM voltage higher than 1.35V generates the maximum LED current. For PWM dimming, VEN/DIM - VINGND must exceed 1.5V. Use a PWM frequency in the range of 100Hz to 2kHz for good dimming linearity. For combined analog and PWM dimming, apply a PWM signal with an amplitude from 0.67V to 1.35V to EN/DIM. Output Short-Circuit Protection (SCP) The MP24833-A features output short-circuit protection (SCP). When the output is shorted to VSS, the voltage on OVP drops below 0.2V, and FB senses no voltage (