MP24894GJ-P

MP24894 Step-Down WLED-Current Controller with Wide 6V to 60V Input Voltage The Future of Analog IC Technology DESCRIPTION FEATURES The MP24894 is a high-efficiency step-down controller. It is designed to operate in continuous current mode (CCM) to power LEDs of high-brightness with a wide input voltage range of 6V to 60V. • • • • • • • • The MP24894 employs a hysteretic control architecture that accurately regulates LED current with a feedback coming from an external high-side current-sense resistor. This control scheme optimizes circuit stabilization and fast response time without loop compensation. Its low 200mV average feedback voltage reduces power loss and improves the converter’s efficiency. Wide 6V to 60V Input Range Able to Drive >1A LED Load Hysteresis Control High Efficiency (>95%) 2500:1 PWM Dimming Ratio Open LED Protection Short LED Protection Thermal Shutdown APPLICATIONS • • • • • The MP24894 implements PWM and analog dimming together through the EN/DIM pin. The MP24894 includes thermal overload protection in case of output overload. Low Voltage Halogen Replacement Low Voltage General Illumination Automotive/Decorative LED Lighting Signs/Emergency Lighting LED Backlighting All MPS parts are lead-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. The MP24894 is available in TSOT6 package. TYPICAL APPLICATION D1 VIN 6V-60V RSENSE CIN IN VCC RS L1 MP24894 EN/DIM GND DR MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 1 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE ORDERING INFORMATION Part Number* Package TSOT6 MP24894GJ Top Marking ACG * For Tape & Reel, add suffix –Z (e.g. MP24894GJ–Z); PACKAGE REFERENCE IN 1 6 VCC RS 2 5 DR EN/DIM 3 4 GND TSOT6 ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance VIN .................................................-0.3V to +65V VRS ..............................................(VIN - 5V) to VIN All Other Pins ...............................-0.3V to +6.5V Continuous Power Dissipation (TA = 25°C) (2) TSOT6 ..................................................... 1.25W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature............... -65°C to +150°C TSOT6 ..................................100 ..... 55 ... °C/W Recommended Operating Conditions (3) Supply Voltage VIN ..............................6V to 60V Operating Junction Temp. (TJ). -40°C to +125°C (4) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the the maximum junction temperature TJ(MAX), junction-to-ambient 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 operation conditions. 4) Measured on JESD51-7, 4-layer PCB. MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 2 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE ELECTRICAL CHARACTERISTICS VIN = 24V, TA = 25°C, unless otherwise noted. Parameter Input voltage Shutdown supply current Quiescent supply current VCC voltage Feedback average voltage (with respect to VIN) Symbol Condition VIN ISD Min 6 Typ 80 Max 60 108 Units V µA 0.3 0.5 mA IQ No Switching Vcc VEN/DIM = 3.5V 5.5 6 VIN-VRS VEN/DIM = 3.5V 194 200 V 206 mV Feedback reference voltage hysterisis EN/DIM enable high voltage EN/DIM enable hysterisis EN/DIM pull-up current EN/DIM pull-down current VEN_HIGH VEN_HYS Min recommended pwm dimming frequency FPWMmin 0.1 kHz FPWMmax 20 kHz 6 2 100 100 Ω Ω V V ns ns 1 MHz VCC Rising 5.6 V Temp Rising Guarantee by Designer 0.4 150 20 V °C °C ±30 VFB_HYS VEN Rising 20 Pull up to 5V Pull down to GND Max recommended pwm dimming frequency Gate driver source resistor Gate driver sink resistor Gate driver output-voltage high Gate driver output-voltage low Minimum on time Minimum off time Recommended maximum operating frequency R_source R_sink VOH VOL TON_MIN TOFF_MIN UVLO threshold voltage(VCC) VUVLOTH UVLO hysteresis Thermal shutdown threshold Thermal shutdown hysteresis VUVLOHYS VGS = 5.5V IDRV = 10mA IDRV = 10mA Guarantee by Designer Guarantee by Designer FMAX 0.29 50 2.8 25 mV 0.34 80 5.5 0.5 MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. V mV μA μA 3 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE TYPICAL CHARACTERISTICS VCC UVLO vs. Temperature 6.45 5.71 6.4 5.7 6.3 6.25 6.2 6.15 6.1 6 -50 0 50 100 0.287 0.286 5.69 5.68 5.67 5.66 Feedback Reference Voltage Valley 227.2 169.4 169.2 169.0 168.8 168.6 168.4 -50 0 50 100 150 0.285 0.284 0.283 0.282 0.281 0.28 5.64 -50 150 FEEDBACK REFERENCE VOLTAGE PEAK (V) FEEDBACK REFERENCE VOLTAGE VALLEY (V) 0.288 5.65 6.05 169.6 EN UVLO vs. Temperature EN UVLO (V) 6.35 VCC UVLO (V) VCC VOLTAGE (V) VCC Voltage vs. Temperature 0 50 100 150 0.279 0.278 -50 0 50 100 150 Feedback Reference Voltage Peak 227.0 226.8 226.6 226.4 226.2 226.0 -50 0 50 100 150 MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 4 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE TYPICAL PERFORMANCE CHARACTERISTICS Performance waveforms are tested on the evaluation board of the Design Example section. VIN = 24V, 3LEDs, IOUT = 1A, TA = 25°C, unless otherwise noted. Efficiency Steady State Input Power On 100 95 90 VSW 20V/div. VSW 20V/div. VGATE 5V/div. VIN 10V/div. 85 80 75 VEN 5V/div. 70 65 60 IL 500mA/div. 10 20 30 40 50 60 Input Power Off VSW 20V/div. VIN 10V/div. VEN 5V/div. ILED 1A/div. ILED 1A/div. EN Power On EN Power Off VSW 20V/div. VSW 20V/div. VGATE 5V/div. VGATE 5V/div. VEN 5V/div. ILED 1A/div. VEN 5V/div. ILED 1A/div. Short LED+ to LED- Protection VSW 20V/div. VGATE 5V/div. VEN 5V/div. ILED 1A/div. VSW 20V/div. VEN 5V/div. VSW 20V/div. VGATE 5V/div. VGATE 5V/div. ILED 1A/div. VLED10V/div. IL 1A/div. MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 5 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE TYPICAL PERFORMANCE CHARACTERISTICS (continued) Performance waveforms are tested on the evaluation board of the Design Example section. VIN = 24V, 3LEDs, IOUT = 1A, TA = 25°C, unless otherwise noted. Short LED+ to LED- Recovery VSW 20V/div. VGATE 5V/div. VLED10V/div. IL 1A/div. Open LED Load Protection Open LED Load Recovery VSW 20V/div. VSW 20V/div. VGATE 5V/div. VGATE 5V/div. IL 1A/div. VEN 5V/div. IL 1A/div. MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 6 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE PIN FUNCTIONS TSOT6 Pin# 1 Name IN 2 RS 3 EN/DIM 4 5 6 GND DR VCC Description Input Supply Pin. Connect a decoupling capacitor from IN pin to GND. LED Current Sense Input. Connect a current-sense resistor that programs LED average current to the IN pin. Enable/Dimming Command Input. A voltage greater than 0.3V turns on the chip. To use PWM dimming, apply a square wave signal to this pin. If diming-off time is larger than 20ms, the IC shuts down. For analog dimming, the EN/DIM pin voltage rises from 0.3V to 2.7V and LED current will change from 20% to 100% of the maximum LED current. Ground. Gate-Driver Output. Connect this pin to the gate of the external MOSFET. Internal Regulator Output. Connect a 1μF decoupling cap from this pin to ground. MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 7 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE FUNCTIONAL BLOCK DIAGRAM D IN CIN IN Rsense RS UVLO VCC Regulator C PWM 1.18V Reference L Enable 0.29V 1.18V VCC Buffer DR Driver EN/DIM R1 Thermal Shutdown R2 Figure 1—MP24894 Functional Block Diagram MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 8 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE OPERATION Steady State The MP24894 is a step-down LED-current controller with hysteresis control that is easily configured for a wide input that ranges from 6V to 60V input. The MP24894 uses a high-side current-sense resistor to detect and regulate LED current. The voltage across the currentsense resistor is measured and regulated in the 200mV±30mV range. The internal 1.18V reference voltage provides a 0.3V reference to enable the part. When VEN>0.3V, the output of the comparator goes high and enables the other blocks. The MP24894 also provides a 5V pull-up voltage as current reference voltage when EN/DIM pin is float. Dimming Control The MP24894 allows the EN/DIM pin to control both Analog and PWM dimming. Whenever the voltage on DIM is less than 0.25V, the chip turns off. For analog dimming, when the voltage on DIM is from 0.3V to 2.7V, the LED current will change from 20% to 100% of the maximum LED current. If the voltage on EN pin is higher than 2.9V, output LED current will equal the maximum LED current. For PWM dimming, the signal amplitude must exceed 3V. Choose a PWM frequency in range of 100Hz to 20kHz for good dimming linearity. The inductor current is sensed through the high-side resistor, Rsense. When the switch is on, R2 (see Figure 1) is shorted and inductor current upper-threshold is fixed by R1. When the switch is off, inductor current lower-threshold is fixed by R1 and R2. The ratio of R1 and R2 determines the current hysteresis. System Soft Start The voltage on the EN/DIM pin provides the inductor current reference. An external capacitor from the EN/DIM pin to ground provides a soft-start delay. When VIN starts, internal voltage source charges the capacitor from 0V to 5V to fulfill soft-start function. MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 9 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE APPLICATION INFORMATION Setting the LED Current The LED current is identical and set by the current sense resistor between the IN pin and RS pin. RSENSE=200mV/ILED For RSENSE=0.2Ω, the LED current is set to 1A Selecting the Inductor Lower value of inductance can result in a higher switching frequency, which causes a larger switching loss. Choose a switch frequency between 100kHz to 600kHz for most application. According to switching frequency, inductor value can be estimated as: V (1- OUT ) × VOUT VIN L= 0.3 × ILED × fSW For higher efficiency, choose an inductor with a DC resistance as small as possible. Selecting the Input Capacitor The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. Choose a capacitor value between 10µF and 22µF for most applications. The voltage rating should be greater than the input voltage. Use a low ESR capacitor for input decoupling. Dimming Control MP24894 provides 1:2500 high-ratio PWM dimming. Apply a 100Hz to 20kHz square waveform to the EN/DIM pin. The average LED current is proportional to PWM duty cycle. Layout Consideration Pay careful attention to the PCB layout and component placement. RSENSE should be placed close to the IN pin and RS pin in order to minimize current sense error. The input loop—including input capacitor, Schottky diode, and Mosfet —should be as short as possible. Design Example Below is a design example following the application guidelines for the specifications: Table 1: Design Example VIN VOUT Iout 24V 10V 1A The detailed application schematic is shown in Figure 2. The typical performance and circuit waveforms have been shown in the Typical Performance Characteristics section. For more device applications, please refer to the related Evaluation Board Datasheets. Selecting the Output Capacitor For most applications, the output capacitor is not necessary. For applications that require that the peak-to-peak LED ripple current falls below 30% of the average current, add a capacitor across the LEDs. Higher capacitor values will result in proportionally lower ripple. A value of 2.2µF will meet most requirements. Selecting Soft-Start Capacitor When selecting a soft-start capacitor, the delay time can be estimated as 0.2ms/nF. For PWM dimming, select C < 2.2nF to eliminate its effect on the average LED current. MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 10 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE B290 VIN R1 0.2 D1 VIN+ LED+ LED+ C2 100V C1 NS 100V C4 R2 50V VIN- LED- LED- IN RS 1 2 L1 U1 C3 EN/DIM MP24894 10V 3 DIM 0 C5 NS R4 0 VCC DR 5 DR EN/DIM GND R3 SW Q1 AM4499N 4 Vcc 6 VCC Figure 2: Application Circuit MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 11 MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE PACKAGE INFORMATION TSOT6 6 See Note 7 EXAMPLE TOP MARK 4 AAAA PIN 1 0.95 BSC 0.60 TYP 2.80 3.00 1 1.20 TYP 1.50 1.70 2.60 TYP 2.60 3.00 3 TOP VIEW RECOMMENDED LAND PATTERN 0.84 0.90 1.00 MAX 0.09 0.20 SEATING PLANE 0.30 0.50 0.95 BSC 0.00 0.10 SEE DETAIL "A" FRONT VIEW SIDE VIEW NOTE: GAUGE PLANE 0.25 BSC 0.30 0.50 0o-8o DETAIL A 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) 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. MP24894 Rev 1.01 www.MonolithicPower.com 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 12