MP24830HS-LF

MP24830 4.5V – 90V, Programmable Frequency White LED Driver The Future of Analog IC Technology DESCRIPTION FEATURES The MP24830 is a 90V white LED driver suitable for either step-down or inverting step-up/down applications. It supports a wide input range with excellent load and line regulation. Its programmable current limit provides customized applications with a wide power range. Current mode operation provides a fast transient response and eases loop stabilization. Fault condition protection includes thermal shutdown, cycle-by-cycle peak-current limiting, open-string protection, and output short-circuit protection. • • • • • • • • • Programmable Maximum Output Current Unique Step-Up/Down Operation (BuckBoost Mode) Wide 4.5V-to-90V Operating Input Range for Step-Down Applications (Buck Mode) Adjustable Switching Frequency Analog and PWM Dimming 0.2V Reference Voltage 10μA Shutdown Mode No Minimum LED Quantity Required Stable with Low ESR Output Ceramic Capacitors Cycle-by-Cycle Over-Current Protection Thermal Shutdown Protection Open-String Protection Output Short-Circuit Protection Available in 14-Pin SOIC and QFN Packages The MP24830 incorporates both DC and PWM dimming onto a single control pin. The separate input reference ground pin allows for direct enable and/or dimming control for a positive-tonegative power conversion. • • • • • The MP24830 requires a minimal number of readily-available external components. It is available in 14-pin SOIC and QFN packages. APPLICATIONS • • • General LED Illumination Automotive LED Lighting LCD Backlight 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 VIN DIM EN INGND C1 C2 3 VDD BST Rcs MP24830 CS 5 DIM 6 EN U1 13 2 DR 1 14 SW Q1 LED+ R9 499k 4 INGND OVP 8 DIMO 11 12 VSS FB 10 RSET COMP 9 7 C3 100pF R6 100k C4 4.3nF R3 4.7k C5 1nF LEDQ2 Si4100DY D2 D1 R10 C9 22pF R7 MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 1 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER ORDERING INFORMATION Part Number Package Top Marking MP24830HS* SOIC-14 MP24830 MP24830HL** QFN-14 24830 * For Tape & Reel, add suffix –Z (e.g. MP24830HS–Z); For RoHS Compliant Packaging, add suffix –LF (e.g. MP24830HS–LF–Z) ** For Tape & Reel, add suffix –Z (e.g. MP24830HL–Z); For RoHS Compliant Packaging, add suffix –LF (e.g. MP24830HL–LF–Z) PACKAGE REFERENCE TOP VIEW TOP VIEW DR 1 14 SW CS 2 13 BST VDD 3 12 VSS INGND 4 11 DIMO DIM 5 10 FB EN 6 9 COMP RSET 7 8 OVP DR 1 14 SW CS 2 13 BST VDD 3 12 VSS INGND 4 11 DIMO DIM 5 10 FB EN 6 9 COMP RSET 7 8 OVP EXPOSED PAD ON BACKSIDE SOIC14 QFN14 ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance Supply Voltage VDD – VSS, VCS – VSS ............90V VSW – VSS .............................. -0.3V to VIN + 0.3V VBST, VDR ..............................................VSW + 6V VEN – VINGND, VDim – VINGND ............. -0.3V to +6V VINGND – VSS ................................... -0.3V to 90V Other pins – VSS ............................. -0.3V to +6V (2) Continuous Power Dissipation (TA = +25°C) SOIC-14 ....................................................1.4W QFN-14 ......................................................2.6W Junction Temperature .............................. 150°C Lead Temperature ................................... 260°C Storage Temperature ............... -65°C to +150°C SOIC-14 ................................. 86 ...... 38 ... °C/W QFN-14................................... 49 ...... 10 ... °C/W Recommended Operating Conditions (3) (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 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 85V Operating Junction Temp. (TJ) -40°C to +125°C MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 2 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER ELECTRICAL CHARACTERISTICES VIN = 12V, TJ = +25°C, all voltages with respect to VSS, unless otherwise noted. Parameters Symbol Feedback Voltage Feedback Current Under Voltage Lockout Threshold Rising Under Voltage Lockout Threshold Hysteresis Operation Current (Quiescent) Supply Current (Quiescent) at EN Off Gate Driver Pull-Up Impedance Gate Driver Pull-Down Impedance Gate Driver Output-High to SW Gate Driver Output-Low to SW DIMO Source Current DIMO Sink Current DIMO Output High DIMO Output Low Oscillator Frequency VFB IFB VUVLOTH VUVLOHY IQ IOFF RPULL UP RPULL Down VOH-SW VOL-SW IDIMOSC IDIMOSK VDIMOH VDIMOL fSW Min. Oscillator Frequency fSWMIN Max. Oscillator Frequency fSWMAX Foldback Frequency fSWFB GM of Error Amplifier Condition 4.5V ≤ VIN ≤ 90V VFB = 0.22V Min 0.192 -50 3.7 VEN = 2V, VFB = 0.25V VEN=0V IDR=10mA IDR=10mA 5.6 IDR=10mA IDR=10mA VFB = 0.15V, RSET=100kΩ VFB = 0.15V, RSET=380kΩ VFB = 0.15V, RSET open 4.6 Typ 0.2 4.1 160 0.8 10 25 7 5.8 0.1 0.05 0.05 5 0.4 Max 0.208 50 4.4 Units 0.5 V nA V mV mA μA Ω Ω V V A A V V 1.1 23 0.3 145 215 265 kHz 30 50 75 kHz 245 365 465 kHz VFB = 0V, VOVP=0V, RSET=100kΩ 30 kHz GM 80 μs Error Amplifier Output Current IOamp 40 μA Current Sensing Gain GCS 20 High-Side Current Limit Threshold VCLTH 45 mV Min. Off-Time tOFFMIN 280 ns 100 3.7 ns μA V V V V (5) Min. On-Time EN Input Current EN OFF Threshold (w/Respect to INGND) EN ON Threshold (w/Respect to INGND) Min. DIM Threshold Max. DIM Threshold LED-Short Threshold for Immediate LatchOff LED Short Delay for Latch-Off LED Short Threshold (5) Thermal Shutdown Open LED OV Threshold Open LED OV Hysteresis tON IENIN VENOFFTH VENONTH VDIMTHL VDIMTHH TTSHD VOVPTH VOVPHY VFB = 0.19V, RSET=100kΩ VEN = 3.3V VEN Falling VEN Rising VFB = 0.2V VFB = 0.2V 0.4 0.6 1.55 1.1 0.7 1.75 1.4 0.8 1.95 600 mV 450 300 160 1.2 50 μs mV °C V mV 1.3 Notes: 5) Guaranteed by design. MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 3 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER PIN FUNCTIONS SOIC14 Name Description 1 DR 2 CS 3 4 5 6 7 8 9 10 Driver Output. Connect it to the high-side MOSFET gate. High-Side Current Sense. For over-current protection and current-mode control. Supply Voltage. Operates from a 4.5V-to-85V unregulated input (with respect to VSS). Needs VDD C1 to prevent large input voltage spikes. INGND Input Ground Reference. Reference for the EN/DIM signal. Dimming Command Input. Selects for DC or PWM dimming. When the DIM pin voltage (with respect to INGND) rises from 0.6V to 1.95V, the LED current changes from 0% to 100% of the DIM maximum LED current. For PWM dimming, apply a 100Hz-to-2kHz square wave with an amplitude greater than 2V. For combined analog and PWM dimming, apply a 100Hz-to-2kHz square wave signal with amplitude from 0.6V to 1.95V. EN Enable. Frequency Set. Connect a resistor to VSS to set the switching frequency, and a 1nF capacitor RSET to VSS to bypass the noise. Leaving this pin open for the 350kHz default operating frequency. Over-Voltage Protection. Use a voltage divider to program OVP threshold. When the OVP pin voltage reaches the 1.2V shutdown threshold, the switch turns off and recovers when the OVP voltage decreases sufficiently. When the OVP pin voltage (with respect to VSS) falls below OVP 0.4V and the FB pin voltage falls below 0.1V, the chip interprets this as a short circuit and the operating frequency will fold back. Program the OVP pin voltage from 0.4V to 1.2V for normal operation. Error Amplifier Output. Connect a 1nF or larger capacitor on COMP and an RC network from COMP FB to COMP to improve the stability and to provide soft-start and PWM dimming. LED Current Feedback Input. A current-sensing resistor between FB and VSS provides circuit FB feedback. The regulation voltage is 0.2V. Short-circuit protection triggers If the FB voltage exceeds 300mV for 450µs or the FB voltage exceeds 600mV. 11 DIMO 12 VSS 13 BST 14 SW DIM Output. Provides for accurate PWM diming control following DIM logic. Connect to the gate of the external dimming MOSFET. Leave floating if dimming accuracy is not a concern. Power Return. Connect to the circuit’s point of lowest potential, which is typically the anode of the Schottky rectifier. Acts as the voltage reference for the regulated output voltage, and layout requires extra consideration. Place this node outside of the D1-to-C1 ground path to prevent switching current spikes from inducing voltage noise. Connect the exposed pad to this pin. Bootstrap. Connect a capacitor between the SW and BST pins to form a floating supply across the power switch driver. Use a 100nF or larger ceramic capacitor to provide sufficient energy to drive the power switch’s gate above the supply voltage. Switch. Connect to the source of the external MOSFET MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 4 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS VEN=5V, VIN=5V to 85V, IOUT=0.5A, L=47μH, TA=25°C, unless otherwise noted. Efficiency vs. Input Voltage Efficiency vs. String Voltage 100 90 8LED 85 3LED 80 75 0 20 40 60 0.4 96 6LED 80 VIN=40V 92 VIN=20V 88 84 80 10 100 VIN VOLTAGE (V) 100 4LED 2LED 0 20 40 60 80 80 500 5 12 19 26 33 200 100 40 60 DIMMING (%) 80 100 50 60 70 2LED, ILED=1A 0.2 0.0 -0.2 -0.4 Buck-Boost ILED vs. Analog Dimming VIN=25V, 3LED, FDIM=0.2kHz 1000 VIN=20V, 3LED, FDIM=0.2kHz 800 300 200 100 0 40 INPUT VOLTAGE (V) IOUT CURRENT (A) 300 30 -0.6 20 30 40 50 60 70 80 90 100 40 400 400 20 0.4 Buck ILED vs. PWM Dimming IOUT CURRENT (A) IOUT CURRENT (mA) 0.6 LED STRING VOLTAGE (V) VIN=25V, 3LED, FDIM=0.2kHz 20 -0.4 Buck ILED Line Regulation vs. VIN 85 70 100 6LED 10LED INPUT VOLTAGE (V) 90 Buck-Boost ILED vs. PWM Dimming 0 0 8LED -0.2 -0.6 10 40 VIN=50V, ILED=1A VIN VOLTAGE (V) 500 35 75 75 70 30 ILED REGULATION (%) EFFICIENCY (%) EFFICIENCY (%) 90 80 25 95 6LED 85 20 3LED 0.0 Buck Efficiency vs. String Voltage ILED=1A 95 15 0.2 LED STRING VOLTAGE (V) Buck Efficiency vs. Input Voltage 100 ILED REGULATION (%) 10LED EFFICIENCY (%) EFFICIENCY (%) 0.6 100 95 70 ILED Line Regulation vs. VIN 0 20 40 60 DIMMING (%) 80 100 600 400 200 0 0.7 0.9 1.1 1.3 1.5 1.7 1.9 ANALOG DIMMING VOLTAGE (V) MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 5 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VEN=5V, VIN=5V to 85V, IOUT=0.5A, L=47μH, TA=25°C, unless otherwise noted. FSW vs. Temperature 500 230 60 400 220 50 40 30 20 -50 -10 30 70 110 200 200 190 100 180 0 -50 150 -10 30 70 110 170 -50 150 7.0 1000 140 6.5 900 120 6.0 800 5.5 700 5.0 600 4.5 -50 -10 30 70 110 500 -50 150 Buck ILED vs. Analog Dimming 1000 30 70 110 150 -10 30 70 110 150 -10 30 70 110 150 100 80 60 40 -50 Buck-Boost Steady State Buck Steady State VIN = 8V, 3LED, IOUT = 1A VIN = 14V, 1LED, IOUT = 1A VIN=20V, 3LED, IOUT=1A, FDIM=0.2kHz 800 VIN 20V/div. 600 VSW 20V/div. 400 VOUT 10V/div. IL 1A/div. 200 0 -10 IQ Current vs. Temperature INPUT VOLTAGE (V) VBST VOLTAGE (V) 210 300 VBST vs. Temperature IOUT CURRENT (A) VFB vs. Temperature 70 DEFAULT FSW (kHz) VCS VOLTAGE (V) VCS vs. Temperature 0.7 0.9 1.1 1.3 1.5 1.7 VIN 50V/div. VSW 20V/div. VOUT 5V/div. IL 1A/div. 1.9 ANALOG DIMMING VOLTAGE (V) MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 6 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VEN=5V, VIN=5V to 85V, IOUT=0.5A, L=47μH, TA=25°C, unless otherwise noted. Buck-Boost Buck-Boost Buck PWM Dimming VIN = 25V, 3LED, FDIM = 200Hz/50% PWM Dimming Analog Dimming VIN = 25V, 3LED, FDIM = 200Hz/50% VIN = 25V, 3LED, VDIM = 0.9A VIN 20V/div. VSW 50V/div. VIN 50V/div. VSW 50V/div. VIN 20V/div. VSW 20V/div. VDIM 5V/div. VDIM 2V/div. VDIM 5V/div. IL 1A/div. IL 1A/div. IL 1A/div. Buck-Boost Power Ramp Up Buck-Boost Enable Power Up Buck-Boost Enable Power Down VIN = 8V, 3LED VIN =40V, 3LED VIN = 40V, 3LED VIN 5V/div. VSW 10V/div. VOUT 10V/div. IL 0.5A/div. VIN 20V/div. VSW 20V/div. VOVP 1V/div. IL 1A/div. VIN 50V/div. VSW 50V/div. VIN 50V/div. VSW 50V/div. VEN 5V/div. VEN 5V/div. IL 1A/div. IL 1A/div. Buck-Boost Open LED Protection Buck-Boost Short LED Protection Buck-Boost Short LED to VSS VIN = 25V, 3LED, ILED = 1A VIN = 16V, 3LED VIN = 25V, 3LED VIN 10V/div. VSW 20V/div. VIN 20V/div. VSW 50V/div. VOUT 10V/div. VOUT 10V/div. IL 1A/div. IL 1A/div. MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 7 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER FUNCTIONAL BLOCK DIAGRAM CS DR DIM DIMO COMP Figure 1: Functional Block Diagram MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 8 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER OPERATION The MP24830 is a current-mode regulator. The error amplifier (EA) output voltage is proportional to the peak inductor current. At the beginning of a cycle, M1 is off. The EA output voltage exceeds the current sense amplifier output, and the current comparator’s output is low. The rising edge of the CLK signal (its frequency equals the switching frequency) triggers the RS flip-flop. The driver turns on the external MOSFET, thus connecting the SW pin and inductor to the input supply. The current-sense amplifier (CSA) senses the increasing inductor current. The PWM comparator compares the sum of the ramp generator and the CSA output against the output of the error amplifier. When the sum of the CSA output and the ramp generator signal exceeds the EA output voltage, the RS flip-flop resets and driver turns off the external MOSFET. The external Schottky rectifier diode (D1) conducts the inductor current. If the sum of the CSA output and the ramp compensation signal does not exceed the EA output for a whole cycle, then the falling edge of the CLK resets the flip-flop. The output of the EA integrates the voltage difference between the feedback and the 0.2V reference: A value of 0.2V-VFB increases the EA output voltage. Since the EA output voltage is proportional to the peak inductor current, increasing its voltage also increases the current delivered to the output. LED Open Protection If the LED is open, there is no voltage on the FB pin. The duty cycle increases until OVPVSS reaches the shutdown threshold set by the external resistor divider. The top switch remains off until the voltage OVP-VSS drops below 1.2V. LED Short Protection If the FB voltage exceeds 600mV, the latches off immediately and DIMO goes low. If the FB voltage exceeds 300mV for 450µs, the IC latches off and DIMO is pulled low. The EN needs to reset to restart the IC. Dimming Control The MP24830 allows both DC and PWM dimming on the DIM pin. For analog dimming, a voltage range from 0.6V to 1.95V linearly sets the LED current from 0% to 100% of the maximum LED current. DIM voltages exceeding 2V results in the maximum LED current. For PWM dimming, use a square signal with an amplitude (VDIM – VINGND) that exceeds 1.95V. For good dimming linearity, select a PWM frequency in range of 100Hz to 2kHz. For a higher dimming frequency or dimming ratio, use the DIMO pin to control an external dimming MOSFET. For combined analog and PWM dimming, apply a PWM signal with amplitude of 0.6V to 1.95V on the DIM pin. Output Short-Circuit Protection The MP24830 integrates output short-circuit protection (SCP) to foldback the operating frequency and decrease power consumption when the output is shorted to VSS. Such shorts cause the voltage on the OVP pin to drop below 0.4V, and the FB pin senses no voltage (>Cp): (1)Compensation network for Buck-boost application The DC modulator gain of the buck-boost power stage (from the output current to the control voltage on COMP pin) is: VOUT × VIN VOUT + VIN DCGain _ PS = VOUT I * VOUT 20 × RCS × ( + OUT ) × (RFB + RLED ) RFB + RLED VOUT + VIN Where RCS is the switch current sensing resistor on CS pin, RLED is the equivalent dynamic resistance of the LED load, as shown in Figure 5. VIN2 2π × L × IOUT × (VOUT + VIN ) RCOMP = fc gm × RFB × DCGain _ PS * fP _ PS That is: RCOMP = 2πfc × COUT × 20 × RCS × (RFB + RLED )(VOUT + VIN ) gm × RFB × VIN Use the maximum input voltage and minimum output voltage to calculate RCOMP. Step 2: Select CZ Set the zero of the compensation network to cancel the minimum pole of the power stage to get: Cz = 1 2π × fP _ PS × RCOMP Choose CZ with the maximum input voltage and maximum output voltage. Step 3: Select CP ΔILED RLED = ΔVLED ΔI LED ΔVLED Set the pole of the compensation network to cancel the minimum RHP zero to get: Cp ≈ 1 2π × fz _ RHP × RCOMP Choose CP with the minimum input voltage and maximum output voltage. Figure 5: LED Dynamic Resistance Equivalent The dominant low-frequency pole of the buckboost power stage is: MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 11 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER (2)Compensation network for Buck application The DC modulator gain of the buck power stage (from the output current to the control voltage) is: DCGain _ Buck = 1 20 × RCS The dominant, low frequency pole of the buck power stage is: fP _ Buck = 1 2 π × (RFB + RLED + RESR ) × COUT The zero produced by the ESR of the output capacitor is: fZ _ ESR = 1 2π × COUT * RESR Where RESR is the ESR of the output capacitor. Step 1: Select RCOMP Choose a crossing frequency, fC, below 1/5×fC to derive the compensation network as follows (assume CZ>>CP): RCOMP _ Buck = fc gm × RFB × DCGain _ Buck * fp _ Buck That is: RCOMP _ Buck = 2πfc × COUT × 20 × RCS × (RFB + RLED + RESR ) gm × RFB Step 2: Select CZ Set the zero of the compensation network to cancel the minimum pole of the Buck power stage to get: Cz _ Buck 1 = 2π × fP _ Buck × RCOMP _ Buck Step 3: Select CP Set the pole of the compensation network to cancel the ESR zero. If the ESR zero is too high, set this pole at around 3 to 5 times fC: Cp ≈ max( 1 1 , ) 2π × fz _ ESR × RCOMP _ Buck 2π × 5fc × RCOMP _ Buck Selecting the Inductor Select the inductor based on the input voltage, the output voltage, and the LED current. Select the inductor to make the circuit operate in continuous current mode (CCM). Select the inductor current rating to ensure that the inductor does not saturate and with consideration to power consumption based on the DC resistance. (1) Selecting the Inductor for Buck-Boost Applications For buck-boost applications, select the inductor based on the following equation: L= fSW VIN × VOUT × (VIN + VOUT ) × ΔIL Where ΔIL is the peak-to-peak inductor current ripple. Design ΔIL to be between 30% and 60% of the average current of the inductor, which is: IL _ AVG = ILED * (1 + VOUT ) VIN Select the inductor with a DC current rating that ensurew that the inductor does not saturated at the peak current of: IL _PK = IL _ AVG + 0.5ΔIL (2) Selecting the Inductor for Buck Applications For buck applications, derive the inductance value from the following equation. L= VOUT × ( VIN − VOUT ) VIN × ΔIL × f SW Where ΔIL is the peak-to-peak inductor ripple current. Choose the inductor ripple current to around 30% to 60% of the maximum load current. The maximum inductor peak current is calculated as: IL(MAX ) = ILOAD + ΔIL 2 Selecting the Input Capacitor The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. For best results, use MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 12 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER ceramic capacitors with X7R dielectrics with low ESR and small temperature coefficients. Select a large-enough capacitor to limit input the voltage ripple, ΔVIN, to less than 5% to 10% of the DC value. CIN > IL _ AVG × VOUT fSW × ΔVIN × (VIN + VOUT ) Selecting the Output Capacitor The output capacitor limits the output voltage ripple, ΔVOUT (normally less than 1% to 5% of the DC value), and ensures feedback loop stability. Use an output capacitor with impedance at the switching frequency. Use ceramic capacitors with low ESR characteristics. COUT > fSW ILED × VOUT × ΔVOUT × (VIN + VOUT ) PC Board Layout Place the high-current paths (VSS, VDD and SW) very close to the device with short, direct, and wide traces. Place the input capacitor as close as possible to the VDD and VSS pins. Place the external feedback resistors next to the FB pin. Keep the switch node traces short and away from the feedback network. Pay special attention is required to the switching frequency loop layout, which should be as small as possible. For buck applications, the switching frequency loop is composed of the input capacitor, the power MOSFET and the Schottky diode. Place the Schottky diode close to the power MOSFET and the input capacitor. For buck-boost or boost applications, the switching frequency loop is composed of the input capacitor, the power MOSFET, the Schottky diode and the output capacitor. Make this component loop as small as possible. For most applications, place the output capacitor close to the input capacitor and the power MOSFET. MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 13 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER TYPICAL APPLICATION CIRCUIT Figure 6: Step-up/down White LED Driver Application Figure 7: Step-down Constant Voltage Converter Application MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 14 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER PACKAGE INFORMATION SOIC-14 0.338(8.55) 0.344(8.75) 0.024(0.61) 8 14 0.063 (1.60) 0.150 (3.80) 0.157 (4.00) PIN 1 ID 0.050(1.27) 0.228 (5.80) 0.244 (6.20) 0.213 (5.40) 7 1 TOP VIEW RECOMMENDED LAND PATTERN 0.053(1.35) 0.069(1.75) SEATING PLANE 0.050(1.27) BSC 0.013(0.33) 0.020(0.51) 0.004(0.10) 0.010(0.25) SEE DETAIL "A" SIDE VIEW FRONT VIEW 0.010(0.25) x 45o 0.020(0.50) GAUGE PLANE 0.010(0.25) BSC 0o-8o 0.016(0.41) 0.050(1.27) 0.0075(0.19) 0.0098(0.25) NOTE: 1) CONTROL DIMENSION IS IN INCHES. DIMENSION IN BRACKET IS IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. 4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.004" INCHES MAX. 5) DRAWING CONFORMS TO JEDEC MS-012, VARIATION AB. 6) DRAWING IS NOT TO SCALE. DETAIL "A" MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 15 MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER QFN-14 2.90 3.10 1.60 1.80 0.30 0.50 PIN 1 ID SEE DETAIL A PIN 1 ID MARKING 1 14 0.18 0.30 3.20 3.40 3.90 4.10 PIN 1 ID INDEX AREA 0.50 BSC 7 8 TOP VIEW BOTTOM VIEW 0.80 1.00 0.20 REF PIN 1 ID OPTION A 0.30x45” TYP. PIN 1 ID OPTION B R0.20 TYP. 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) JEDEC REFERENCE IS MO-229, VARIATION VGED-4. 5) DRAWING IS NOT TO SCALE. 0.25 3.30 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. MP24830 Rev. 1.02 www.MonolithicPower.com 4/29/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 16