MP24895-AGH-Z

MP24895A 6V - 36V, Step-Down, White LED Driver DESCRIPTION FEATURES The MP24895A is step-down LED driver designed in continuous current mode for driving the high-brightness LEDs from a wide input voltage of 6V to 36V.          The MP24895A employs a hysteretic control scheme to regulate the LED current. This control scheme provides optimal loop stabilization and a very quick response time. For high accuracy, the MP24895A senses the LED current by an external high-side resistor. Its low 100mV average feedback voltage reduces power loss and improves efficiency. The MP24895A implements pulse-width modulation (PWM) and analog dimming on EN/DIM. Full protection features include under-voltage lockout (UVLO) and thermal overload protection to prevent damage in the event of an output overload. Internal 36V MOSFET Wide 6V to 36V Input Range 1A Output Current High Efficiency Hysteretic Control PWM and Analog Dimming 1000:1 PWM Dimming Resolution UVLO, Thermal Shutdown Available in an MSOP-8 EP Package APPLICATIONS      Low-Voltage Halogen Replacement Low-Voltage General Illumination Automotive/Decorative LED Lighting Signs/Emergency Lighting LED Backlighting 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. The MP24895A is available in an MSOP-8 EP package. TYPICAL APPLICATION MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 1 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER ORDERING INFORMATION Part Number MP24895-AGH* Package MSOP-8 EP Top Marking See Below * For Tape & Reel, add suffix –Z (e.g. MP24895-AGH–Z) TOP MARKING Y: Year code W: Week code LLL: Lot number 24895A: Product code of MP24895-AGH PACKAGE REFERENCE TOP VIEW MSOP-8 EP MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 2 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance (4) VIN, VSW .........................................-0.3V to +40V VRS ................................................ VIN - 5V to VIN All other pins ................................-0.3V to +6.3V Continuous power dissipation (TA = +25°C) (2) ................................................................. 1.56W Junction temperature ................................150°C Lead temperature .....................................260°C Storage temperature ................ -65°C to +150°C MSOP-8 EP ......................... 50 ........ 12 ... °C/W Recommended Operating Conditions (3) Supply voltage (VIN) ............................ 6V to 36V Operating junction temp. (TJ). ..... -40°C to +125°C 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 is not guaranteed to function outside of its operation conditions. 4) Measured on JESD51-7 4-layer board. MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 3 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER ELECTRICAL CHARACTERISTICS VIN = 24V, TJ = -40°C to 125°C (6), unless otherwise noted. Parameter Input voltage IN under-voltage lockout Under-voltage lockout hysteresis Shutdown supply current Quiescent supply current Symbol VIN VIN_UVLO Feedback reference voltage (with respect to VIN) VIN-VRS EN/DIM enable high voltage EN/DIM enable hysteresis EN/DIM pull-up resistor Internal reference voltage Switch on resistance Minimum on time (5) Minimum off time (5) Thermal shutdown temperature (5) VEN_HIGH VEN_HYS REN VREF RDS_ON tON_MIN tOFF_MIN TOTP Thermal shutdown hysteresis (5) TOTP HYS ISD IQ Condition VIN rising Min 6 4.7 No switching TJ = 25°C, VEN/DIM = 1.28V TJ = -40°C to 125°C, VEN/DIM = 1.28V VEN/DIM rising 94 Typ 5.3 700 170 0.7 100 92 0.19 VEN/DIM = 0.3V 1.24 0.25 50 45 1.28 0.2 100 80 150 Max 36 5.9 250 1.1 Units V V mV µA mA 106 mV 108 mV 0.31 90 V mV kΩ V Ω ns ns °C 1.32 0.4 15 °C NOTES: 5) Guaranteed by design. 6) Not tested in production, guaranteed by characterization. Typical value represents the most likely parametric norm at +25°C. MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 4 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS VIN = 18V, VOUT = 10V, L = 47µH, TA = 25°C, unless otherwise noted. MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 5 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 18V, VOUT = 10V, L = 47µH, TA = 25°C, unless otherwise noted. MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 6 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 18V, VOUT = 10V, L = 47µH, TA = 25°C, unless otherwise noted. MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 7 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER PIN FUNCTIONS Pin # Name 1 RS 2 3 ,7 GND NC 4 EN/DIM 5, 6 SW 8 IN Description LED current sense input. Connect a current-sense resistor to program the LED average current to IN. Ground. Not connected. Enable/dimming command input. For PWM dimming, apply a square wave signal to EN/DIM. For analog dimming, apply a 0.3V to 2.5V DC voltage to control the LED current range linearly from 25% to 200%. Turn off the output current when pulling EN/DIM below 0.2V. Leave EN/DIM open for normal operation (VEN/DIM = 1.28V). Drain of internal MOSFET. Connect the inductor common terminal and Schottky anode to SW. Input supply. Connect an appropriate decoupling capacitor from IN to GND. MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 8 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER BLOCK DIAGRAM Figure 1: Functional Block Diagram MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 9 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER OPERATION Steady State The MP24895A is a hysteretic-controlled, stepdown LED driver that can be configured easily for various applications with an input range from 6V to 36V. The converter employs a high-side current-sense resistor to detect and regulate the LED current. The voltage across the current-sense resistor is measured and regulated within 100mV ± 20mV. The internal 1.28V reference voltage provides a 0.2V reference to enable the part and a 1.28V pull-up voltage as the current reference. When VEN/DIM > 0.2V, the output of the comparator goes high, and the other blocks are enabled. A high-side resistor (RSENSE) senses the output current. When the switch is on, R2 is shorted, and R1 sets the output current upper-threshold. When the switch is off, R1 and R2 set the output current lower-threshold. The ratio of R1 and R2 determines the current hysteresis. Enable Control Once the input voltage is applied, the internal 1.28V reference is connected to EN/DIM through the pull-up resistor. If EN/DIM is left open, the IC starts up automatically to the maximum brightness. Add a capacitor to EN/DIM to program a soft-start time. Apply an external DC voltage to EN/DIM to control the current-sense voltage reference linearly for analog dimming. Apply an external pulse-width modulation (PWM) voltage with an amplitude of 1.28V to EN/DIM to achieve PWM dimming. For additional information on the flexible external PWM dimming method, please refer to the Selecting the Dimming Control Mode section on Page 11. System Soft Start The voltage on EN/DIM is the inductor current reference. An external capacitor from EN/DIM to ground provides a soft-start delay. When VIN starts up, the internal voltage source charges the capacitor from 0V to 1.28V for soft start. Dimming Control The MP24895A provides two dimming methods: PWM dimming and DC analog dimming. To use PWM dimming, apply a square wave to EN/DIM. To use analog dimming, apply a 0.3V to 2.5V DC voltage to EN/DIM to control the LED current range linearly from 25% to 200%. MP24895A Rev. 1.0 www.MonolithicPower.com 2/3/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 10 MP24895A – 6V - 36V, STEP-DOWN, WHITE, LED DRIVER APPLICATION INFORMATION Setting the LED Current The LED current is set by the current-setting resistor between IN and RS, which can be calculated with Equation (1): RSET=100mV/ILED (1) For RSET = 0.2Ω, the LED current is 500mA. Selecting the Inductor A lower inductor value results in higher switching frequencies and larger switching loss. For most applications, select a switching frequency between 200kHz and 600kHz. Estimate the inductor value based on the desired switching frequency with Equation (2): V (1- OUT )  VOUT VIN (2) L 0.4  ILED  fSW Selecting the Soft-Start Capacitor The delay time with a soft-start capacitor can be estimated by 0.2ms/nF. In PWM dimming, select a capacitor