MXHV9910 Off-Line, High Brightness LED Driver Features Description • 8VDC to 450VDC Input Voltage Range • >90% Efficiency • Drives Multiple LEDs in Series/Parallel Combinations • Regulated LED Drive Current • Linear or PWM Brightness Control • Resistor-Programmable Oscillator Frequency • RoHS Compliant The MXHV9910 is a low-cost, high-brightness (HB) LED driver manufactured using Clare’s high-voltage BCDMOS on SOI process. This driver has internal circuitry that allows it to operate from a universal AC line or from 8VDC to 450VDC. This highly versatile input operating voltage enables this IC to be used in a broad range of HB LED applications. The driver features a fixed-frequency, peak-current control method, which provides an ideal solution for driving multiple LEDs in series and in parallel. In addition, LED dimming can be implemented by applying a small DC voltage to the LD pin, or by applying a low-frequency digital PWM signal to the PWMD pin. Applications • Flat-Panel Display RGB Backlighting • Signage and Decorative LED Lighting • DC/DC or AC/DC LED Driver Applications The MXHV9910 is available in a standard 8-lead SOIC package and a thermally enhanced 8-lead SOIC package with an Exposed Thermal Pad (EP) Ordering Information Part MXHV9910B MXHV9910BTR MXHV9910BE MXHV9910BETR Description SOIC-8 (100/Tube) SOIC-8 Tape & Reel (2000/Reel) SOIC-8 EP (100/Tube) With Exposed Thermal Pad SOIC-8 EP Tape & Reel (2000/Reel) With Exposed Thermal Pad MXHV9910 Block Diagram VDD VIN 6 1 Voltage Regulator Voltage Reference 250mV RT 8 OSC + LD 7 PWM Control 4 GATE 2 CS + PWMD GND DS-MXHV9910-R02 5 3 www.clare.com 1 MXHV9910 1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Package Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 3 3 4 4 4 2 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 LED Driver Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.1 Input Voltage Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.2 Current Sense Resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.3 Current Sense Blanking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.4 Enable/Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.5 Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.6 Inductor Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.7 Gate Output Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.8 Linear Dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.9 PWM Dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.10 Combination Linear and PWM Dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5 5 6 6 7 7 7 7 8 8 8 9 3 Manufacturing Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Moisture Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 ESD Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Board Wash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 Mechanical Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 Packaging Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.1 Tape & Reel Information for both 8-Pin Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 www.clare.com 10 10 10 10 10 11 12 12 R02 MXHV9910 1. Specifications 1.1 Package Pinout 1.2 Pin Description Pin# Name 1 VIN 2 CS VIN 1 8 RT CS 2 7 LD 3 4 GND GATE GND 3 6 VDD 5 PWMD GATE 4 5 PWMD 6 VDD 7 LD 8 RT EP - Description Input voltage LED Current Sense input. Internal current sense threshold is set at 250mV. The external sense resistor sets the maximum LED current. Device Ground External MOSFET gate driver output Low-frequency PWM dimming control input with internal pull-down resistor. Regulated supply voltage output. Requires a storage capacitor to GND. Can be overdriven by external voltage applied to VDD . Linear Dimming. Apply a voltage less than VCS(high) to dim the LED(s). Resistor to GND sets the oscillator/primary PWM frequency. Electrical and thermal conductive pad on the bottom of the MXHV9910BE. Connect this pad to ground, and provide sufficient thermal coupling to remove heat from the package. 1.3 Absolute Maximum Ratings Parameter Symbol Maximum Unit VIN -0.5 to +460 V CS, LD, PWMD, GATE -0.3 to VDD+0.3 V VDD.EXT 15 V 2.5 W 0.975 W TJmax 150 °C Operating Temperature TA -40 to +85 °C Junction Temperature (Operating) TJ -40 to +150 °C TSTG -55 to +150 °C Input Voltage to GND Inputs & Outputs Voltage to GND VDD , Externally Applied Power Dissipation SOIC-8 With Thermal Tab SOIC-8 W/O Thermal Tab Maximum Junction Temperature Storage Temperature PD Electrical absolute maximum ratings are at 25°C. Absolute maximum ratings are stress ratings. Stresses in excess of these ratings can cause permanent damage to the device. Functional operation of the device at conditions beyond those indicated in the operational sections of this data sheet is not implied. R02 www.clare.com 3 MXHV9910 1.4 Recommended Operating Conditions Parameter Input Voltage Range PWMD Frequency Operating Temperature Symbol VIN fPWMD TA Minimum Nominal Maximum 8 -40 500 - 450 +85 Unit VDC Hz °C 1.5 Electrical Characteristics Unless otherwise specified, all electrical specifications are provided for TA=25C. Parameter Input Input DC Voltage Range Shut-Down Mode Supply Current Maximum Voltage to VDD Pin Regulator Conditions Symbol Minimum Typical Maximum Unit DC Input Voltage PWMD to GND, VIN=15 to 450V External Voltage applied to VDD Pin VIN 0.3 - 450 0.6 12 VDC IINSD VDDmax 8 - VIN=15V to 450V, IDD(ext)=0, GATE Output=Open VDD 7.2 7.8 8.4 VDC - IDD(ext) - - 2 mA VIN=15V, IL=1mA VDD - - 200 mV VIN=8V to 450V VIN=8V to 450V VIN=12V, VPWMD=VDD VEN(low) VEN(high) REN 2.4 70 115 0.5 150 CS=0V CS=VDD -40°C < TA < 85°C RT=400k RT=400k IIL IIH VCS(high) tBLANK tDELAY 200 - -45 0 400 300 -90 ±15 280 - mV ns ns RT=400k fS 51 64 77 kHz IOUT= -10mA IOUT=10mA CGATE=500pF CGATE=500pF VGATE(hi) VGATE(lo) tRISE tFALL VDD-0.3 - 0.03 16 7 0.3 - Symbol Minimum Typical Maximum Unit RJA - 50 128 - °C/W Internal Voltage Regulator VDD Current Available for External Circuitry VDD Load Regulation PWM Dimming PWMD Input Low Voltage PWMD Input High Voltage PWMD Pull-Down Resistance Current Sense Comparator Current Sense (CS) Input Current CS Low CS High Current Sense Threshold Voltage Current Sense Blanking Interval Delay from CS Trip to Gate Low Oscillator Oscillator Frequency (Gate Driver) Gate Driver Gate High Output Voltage Gate Low Output Voltage Gate Output Rise Time Gate Output Fall Time mA V V k A V ns 1.6 Thermal Characteristics Parameter Thermal Resistance, Junction-to-Ambient 1 4 Package SOIC-8 With Thermal Pad (BE) SOIC-8 W/O Thermal Pad (B) 1 Use of a four-layer PCB can improve thermal dissipation (reference EIA/JEDEC JESD51-5). www.clare.com R02 MXHV9910 2. Functional Description Figure 1 Typical Application Circuit 8-450V VDD 6 VDD 1 VIN Voltage Regulator Voltage Reference 250mV 8 RT OSC + 7 LD PWM Control GATE 4 CS 2 + 5 PWMD 3 GND RSENSE 2.1 Overview The MXHV9910 is a high-efficiency, low cost, off-line LED driver designed using Clare's state of the art BCDMOS on SOI process. The driver can operate from a DC supply voltage between 8 to 450VDC . The versatile input supply voltage range enables this driver to be used in a broad range of applications such as flat panel display RGB backlighting, signage, decorative LED lighting, and incandescent lamp replacement. The MXHV9910 IC is configured in a buck converter topology, which is a perfect choice for off-line and DC applications driving multiple LEDs in series or parallel. This method provides excellent efficiency and enables a buck switcher design using a minimum number of external components. An external current sense resistor sets the peak current to the LED string. In addition, LED dimming can be implemented by either applying a DC control voltage to the LD pin, or by applying a low frequency, pulse-width modulated digital signal to the PWMD pin (typically 500 Hz). up the voltage across the current sense resistor located at the CS pin. When the rising voltage at the current sense, CS, pin exceeds VCS(high), the internally set threshold, the gate drive signal goes low and turns off the external power MOSFET. Turning the power MOSFET off causes the inductor current to decay until the next rising edge of the clock, and the process repeats. The peak current threshold is set by comparing the voltage developed across the RSENSE resistor to the internal threshold, VCS(high). This default threshold can be overridden externally by applying a voltage less than VCS(high) to the LD pin. The lower of these two thresholds limits the peak current in the inductor A soft-start function can be implemented by slowly ramping up the DC voltage at the LD pin from 0mV to a level greater than 250mV. Figure 2 shows a typical recommended soft-start circuit design. Figure 2 Soft-Start RC Network 2.2 LED Driver Theory of Operation R02 51kΩ MXHV9910 The gate driver pulse width mode (PWM) control circuit is enabled by connecting the PWMD pin to the VDD pin. When enabled, the rising edge of each internal clock turns on the gate driver and the external power MOSFET, causing the inductor current to ramp www.clare.com VIN CS GND GATE RT LD VDD PWMD 2kΩ 0.1μF 5 MXHV9910 Figure 3 MXHV9910 Waveforms (From Application Circuit in Figure 6) Time Scale: 5s/div CH1: 50mA/div FS 65kHz Max 77mA CH2: 10V/div CH3: 5mV/div x 10 2.2.1 Input Voltage Regulator The MXHV9910 has an internal voltage regulator that can work with input voltages ranging from 12VDC to 450 VDC. When the input voltage applied at the VIN pin is greater than 12VDC , the internal voltage regulator regulates this voltage down to a typical 7.8V. The VDD pin is the internal regulator output pin and must be bypassed by a low ESR capacitor, typically 0.1F, to provide a low impedance path for high frequency switching noise. The MXHV9910 driver does not require the bulky start-up resistors typically needed for off-line controllers. An internal voltage regulator provides sufficient voltage and current to power the internal IC circuits. This voltage is also available at the VDD pin, and can be used as bias voltage for external circuitry. The internal voltage regulator can by bypassed by applying an external DC voltage to the VDD pin that is slightly higher than the internal regulator’s maximum output voltage. This feature reduces power dissipation of the integrated circuit and is more suitable in isolated applications where an auxiliary transformer winding could be used to supply VDD . The total input current drawn by the VIN pin is equal to the integrated circuit quiescent current, which is 0.6mA maximum, plus the gate driver current. The gate driver current is dependant on the switching frequency and the gate charge of the external power MOSFET. The following equation can be used to approximate the VIN input current: I IN 0.6mA + Q GATE f S Where QGATE is the total gate charge of the external power MOSFET, and fS is the switching oscillator frequency. 2.2.2 Current Sense Resistor The peak LED current is set by an external current sense resistor connected from the CS pin to ground. The value of the current sense resistor is calculated based on the desired average LED current, the current sense threshold, and the inductor ripple current. The inductor is typically selected to be large enough to keep the ripple current (the peak-to-peak difference in the inductor current waveform) to less than 30% of the average LED current. Factoring in this ripple current requirement, the current sense resistor can be determined by: V csth R sense = ------------------------------------------------------------ 1 + 0.5 r iout I LED Where: • Vcsth = nominal current sense threshold = 0.25V • riout = inductor ripple = 0.3 • ILED = average LED current The power dissipation rating of the sense resistor can be found with the following formula: 2 P = I LED R sense 6 www.clare.com R02 MXHV9910 It is a good practice to select a power rating that is at least twice the calculated value. This will give proper margins, and make the design more reliable. Figure 4 Resistor Selection Oscillator Frequency, fS, vs. RT (TA=27ºC) 250 2.2.3 Current Sense Blanking 2.2.4 Enable/Disable Connecting the PWMD pin to VDD enables the gate driver. Connecting PWMD to GND disables the gate driver and sets the device into the shut-down mode. In the shut-down mode, the gate output drive is disabled while all other functions remain active. The maximum quiescent current in the shut-down mode is 0.6mA. 200 Frequency (kHz) The MXHV9910 has an internal current-sense blanking circuit. When the power MOSFET is turned on, the external inductor can cause an undesired spike at the current sense pin, CS, initiating a premature termination of the gate pulse. To avoid this condition, a typical 400ns internal leading edge blanking time is implemented. This internal feature eliminates the need for external RC filtering, thus simplifying the design. During the current sense blanking time, the current limit comparator is disabled, preventing the gate-drive circuit from terminating the gate-drive signal. 150 100 50 0 0 The typical off-line LED driver switching frequency, fS, is between 30kHz and 120kHz. This operating range gives designers a reasonable compromise between switching losses and inductor size. The internal RC oscillator has a frequency accuracy of ±20%. Figure 4 shows the RT resistor selection for the desired fS. 400 600 800 1000 1200 RT (kΩ) 2.2.6 Inductor Design The inductor value is determined based on LED ripple current, maximum on-time, the forward voltage drop of all LEDs in a string at the desired current, and the minimum input voltage, which is based on design requirements. The maximum on-time is determined by the duty cycle and switching frequency. The maximum duty cycle is given by: V LEDstring D max = -------------------------V in 2.2.5 Oscillator The MXHV9910 operates in a constant frequency mode. Setting the oscillator frequency is achieved by connecting an external resistor between RT and GND. In general, switching frequency selection is based on the inductor size, controller power dissipation, and the input filter capacitor. 200 Where: • VLEDstring is the LED string voltage at desired average LED current. • Vin is the minimum input voltage to VIN The maximum duty cycle must be restricted to less than 50% in order to prevent sub-harmonic oscillations and open loop instability. The converter maximum ON-time is given by: D max t ONmax = ------------fs Where fs is the switching frequency of the internal oscillator. The inductor value for the given ripple is: V in – V LEDstring t ONmax L min = --------------------------------------------------------------------r iout I LED R02 www.clare.com 7 MXHV9910 2.2.8 Linear Dimming The inductor peak current rating is given by: A linear dimming function can be implemented by applying a DC control voltage to the LD pin. By varying this voltage, the user can adjust the current level in the LEDs, which in turn will increase or decrease the light intensity. The control voltage to the LD pin can be generated from an external voltage divider network from VDD . This function is useful if the user requires a LED current at a particular level and there is no exact Rsense value available. Note that applying a voltage higher than the current sense threshold voltage at the LD pin will not change the output current due to the fixed threshold setting. When the LD pin is not used, it should be connected to VDD . I Lmax = I LED 1 + 0.5 r iout 2.2.7 Gate Output Drive The MXHV9910 uses an internal gate drive circuit to turn on and off an external power MOSFET. The gate driver can drive a variety of MOSFETs. For a typical off-line application, the total MOSFET gate charge will be less than 25nC. Figure 5 Typical Linear Dimming Application Circuit Fuse F2 2A LD Monitor BR1 AC AC AC Input 90 - 265Vrms + D1 BYV26B NTC1 C1 0.1μF 400V R1 402kΩ C2 22μF 400V VIN CS GND GATE L1 4.7mH HB LEDs 350mA R2 51kΩ MXHV9910 RT LD VDD PWMD RA1 5.0kΩ IXTA8N50P C3 2.2μF 16V R3 0.56Ω C4 0.1μF 25V 2.2.9 PWM Dimming The signal can be generated by a microcontroller or a pulse generator with a duty cycle proportional to the amount of desired light output. When PWMD is low, gate drive is off; when PWMD is high, gate drive is enabled. Pulse width modulation dimming can be implemented by driving the PWMD pin with a low frequency square wave signal in the range of a few hundred Hertz. The PWMD signal controls the LED brightness by gating the PWM gate driver output pin GATE. Figure 6 Buck Driver for PWM Dimming Application Circuit VIN 12 - 30VDC D1 Schottky 40V 10μF 50V Q1 220μH HB LEDs 900mA Max ASMT-Mx00 MXHV9910 VIN CS GND GATE 402kΩ RT LD VDD PWMD CPC1001N* R1 0.27Ω 0.1μF 50V PWM *Optional Isolation 8 www.clare.com R02 MXHV9910 2.2.10 Combination Linear and PWM Dimming A combination of linear and PWM dimming techniques can be used to achieve a large dimming ratio. Note: The output current will not go to zero if the LD pin is pulled to GND because the minimum gate driver on-time is equal to the current sense blanking interval. To achieve zero LED current, the PWMD pin should be used. R02 www.clare.com 9 MXHV9910 3. Manufacturing Information 3.1 Moisture Sensitivity All plastic encapsulated semiconductor packages are susceptible to moisture ingression. Clare classified all of its plastic encapsulated devices for moisture sensitivity according to the latest version of the joint industry standard, IPC/JEDEC J-STD-020, in force at the time of product evaluation. We test all of our products to the maximum conditions set forth in the standard, and guarantee proper operation of our devices when handled according to the limitations and information in that standard as well as to any limitations set forth in the information or standards referenced below. Failure to adhere to the warnings or limitations as established by the listed specifications could result in reduced product performance, reduction of operable life, and/or reduction of overall reliability. This product carries a Moisture Sensitivity Level (MSL) rating as shown below, and should be handled according to the requirements of the latest version of the joint industry standard IPC/JEDEC J-STD-033. Device Moisture Sensitivity Level (MSL) Rating MXHV9910B / MXHV9910BE MSL 1 3.2 ESD Sensitivity This product is ESD Sensitive, and should be handled according to the industry standard JESD-625. 3.3 Reflow Profile This product has a maximum body temperature and time rating as shown below. All other guidelines of J-STD-020 must be observed. Device Maximum Temperature x Time MXHV9910B / MXHV9910BE 260°C for 30 seconds 3.4 Board Wash Clare recommends the use of no-clean flux formulations. However, board washing to remove flux residue is acceptable, and the use of a short drying bake may be necessary. Chlorine-based or Fluorine-based solvents or fluxes should not be used. Cleaning methods that employ ultrasonic energy should not be used. Pb 10 RoHS 2002/95/EC e3 www.clare.com R02 MXHV9910 3.5 Mechanical Dimensions 8-Pin SOIC Package Recommended PCB Land Pattern 0.19 - 0.25 (0.008 - 0.010) 5.80 - 6.20 (0.23 - 0.24) 1.55 (0.061) 0.40 - 1.27 (0.016 - 0.050) 3.80 - 4.00 (0.15 - 0.16) 5.40 (0.213) PIN 1 0.33 - 0.51 (0.013 - 0.020) 1.27 BSC (0.05 BSC) 0.60 (0.024) 4.80 - 5.00 (0.19 - 0.20) 1.27 (0.050) 0.10 - 0.25 (0.004 - 0.010) 0.394 - 0.648 (0.016 - 0.026) Dimensions mm (inches) 1.35 - 1.75 (0.053 - 0.069) 8-Pin SOIC Package with Exposed Thermal Pad Recommended PCB Land Pattern 0.19 - 0.25 (0.008 - 0.010) 5.80 - 6.20 (0.23 - 0.24) 1.55 (0.061) 0.40 - 1.27 (0.016 - 0.050) 3.80 - 4.00 (0.15 - 0.16) 2.40 (0.09) PIN 1 0.33 - 0.51 (0.013 - 0.020) 2.40 (0.09) 5.40 (0.213) 1.27 BSC (0.05 BSC) 2.032 - 2.413 (0.080 - 0.095) 0.60 (0.024) 1.27 (0.050) 4.80 - 5.00 (0.19 - 0.20) 0.00 - 0.13 (0.000 - 0.005) 0.394 - 0.648 (0.016 - 0.026) 1.35 - 1.75 (0.053 - 0.069) 2.032 - 2.413 (0.080 - 0.095) Dimensions mm (inches) Note: Thermal pad should be electrically connected to GND, pin 3. R02 www.clare.com 11 MXHV9910 3.6 Packaging Information 3.6.1 Tape & Reel Information for both 8-Pin Packages 330.2 DIA. (13.00 DIA.) Top Cover Tape Thickness 0.102 MAX. (0.004 MAX.) W=12.00 (0.472) B0=5.30 (0.209) K0= 2.10 (0.083) A0=6.50 (0.256) P=8.00 (0.315) User Direction of Feed Embossed Carrier Embossment Dimensions mm (inches) NOTE: Tape dimensions not shown comply with JEDEC Standard EIA-481-2 For additional information please visit www.clare.com Clare, Inc. makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication and reserves the right to make changes to specifications and product descriptions at any time without notice. Neither circuit patent licenses or indemnity are expressed or implied. Except as set forth in Clare’s Standard Terms and Conditions of Sale, Clare, Inc. assumes no liability whatsoever, and disclaims any express or implied warranty relating to its products, including, but not limited to, the implied warranty of merchantability, fitness for a particular purpose, or infringement of any intellectual property right. The products described in this document are not designed, intended, authorized, or warranted for use as components in systems intended for surgical implant into the body, or in other applications intended to support or sustain life, or where malfunction of Clare’s product may result in direct physical harm, injury, or death to a person or severe property or environmental damage. Clare, Inc. reserves the right to discontinue or make changes to its products at any time without notice. Specifications: DS-MXHV9910-R02 © Copyright 2011, Clare, Inc. All rights reserved. Printed in USA. 8/8/2011 12 www.clare.com R02 MXHV9910 265VAC Demo Board LED- 350mA max LED+ VDD MONITOR Vin RA1 - External Current Sense Threshold Adjust 90 to 265 VAC EXTERNAL POWER Vin LD MONITOR The LD pin is connected to the wiper of RA1. LED current may be reduced in a linear fashion by adjusting RA1. Warning: This demonstration board must be powered through an isolation transformer before connecting to any external AC instrumentation. JP1 - EXTERNAL PWMD CONTROL INPUT Connecting the PWMD pin to VDD enables the converter. Applying a PWM TTL signal between the PWMD pin and GND adjusts the average output current to the LEDs according to the duty cycle. FUSE F2 2A J2 R1 402kΩ BR1 VIN 90-265VAC EXT. POWER VDD MONITOR + AC AC LD MONITOR df04s VIN C1 0.1μF 400V D1 BYV26B NTC1 C2 22μF 400V 1 2 2 L1 4.7mH 3 1 Q1 IRF840AS J1 R2 51kΩ MXHV9910 8-PIN SOIC 4 VIN RT CS LD PGND VDD GATE PWMD 3 RA1 5kΩ 6 1 R4 0.56Ω JP1 www.clare.com 2 C2 2.2μF 16V 5 R3 0Ω LED CONNECTION 2/15/10 7 DUT1 LED+ LED- 8 3 C4 0.1μF 25V PWMD Page 1 For additional information please visit www.clare.com Clare, Inc. makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication and reserves the right to make changes to specifications and product descriptions at any time without notice. Neither circuit patent licenses or indemnity are expressed or implied. Except as set forth in Clare’s Standard Terms and Conditions of Sale, Clare, Inc. assumes no liability whatsoever, and disclaims any express or implied warranty relating to its products, including, but not limited to, the implied warranty of merchantability, fitness for a particular purpose, or infringement of any intellectual property right. The products described in this document are not designed, intended, authorized, or warranted for use as components in systems intended for surgical implant into the body, or in other applications intended to support or sustain life, or where malfunction of Clare’s product may result in direct physical harm, injury, or death to a person or severe property or environmental damage. Clare, Inc. reserves the right to discontinue or make changes to its products at any time without notice. Specifications: MXHV9910-265VAC-DemoBd © Copyright 2010, Clare, Inc. All rights reserved. Printed in USA. 2/15/10 2/15/10 www.clare.com Page 2 MXHV9910 30VDC Demo Board Vin+ LED+ EXT POWER 12 to 30VDC 6 to 15VDC 900mA max Vin- LED- EXTERNAL (RA1) Current Sense Threshold Adjust VDD Monitor JP2 - INTERNAL/EXTERNAL CURRENT THRESHOLD SELECT When the LD pin is connected to RA1 through JP2, LED current may be reduced in a linear fashion by adjusting RA1. JP1 - EXTERNAL PWMD CONTROL INPUT Connecting the PWMD pin to VDD enables the converter. Applying a PWM TTL signal between the PWMD pin and GND adjusts the average output current to the LEDs according to the duty cycle. VIN + VIN - LED + C1 10μF 50V LED D1 40V, 1A Schottky L1 220μH, 1A 1 3 4 1 Q1 SI2308DS-T1-E3 2 R3 51kΩ DUT1 2 3 VDD R2 402kΩ VIN RT CS LD PGND VDD GATE PWMD 8 C4 2.2μF 25V 7 RA1 5kΩ 6 5 MXHV9910 8-Pin SOIC C3 0.1μF 25V D2 1N914 R1 0.27Ω 1/4W GND JP1 PWMD 2/15/10 www.clare.com JP2 Page 1 For additional information please visit www.clare.com Clare, Inc. makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication and reserves the right to make changes to specifications and product descriptions at any time without notice. Neither circuit patent licenses or indemnity are expressed or implied. Except as set forth in Clare’s Standard Terms and Conditions of Sale, Clare, Inc. assumes no liability whatsoever, and disclaims any express or implied warranty relating to its products, including, but not limited to, the implied warranty of merchantability, fitness for a particular purpose, or infringement of any intellectual property right. The products described in this document are not designed, intended, authorized, or warranted for use as components in systems intended for surgical implant into the body, or in other applications intended to support or sustain life, or where malfunction of Clare’s product may result in direct physical harm, injury, or death to a person or severe property or environmental damage. Clare, Inc. reserves the right to discontinue or make changes to its products at any time without notice. Specifications: MXHV9910-30VDC-DemoBd © Copyright 2010, Clare, Inc. All rights reserved. Printed in USA. 2/15/10 2/15/10 www.clare.com Page 2 MXHV9910 Design Considerations Application Note AN-300 1 Off-line LED Driver using MXHV9910 This application note provides general guidelines for designing an off-line LED driver using the MXHV9910. The MXHV9910 is a constant frequency buck converter specifically designed to provide a low cost, minimal external component solution for off-line LED applications. The converter operates in a continuousconduction, peak-current control mode with no slope compensation. When designing an LED driver with the MXHV9910, the duty cycle must be restricted to less than 50% in order to prevent subharmonic oscillations. The MXHV9910 has two current sense thresholds: one is internally set at 250mV, and the other can be Figure 1 externally set at the LD pin. The lower of these two thresholds determines the LED peak current in conjunction with the current sense resistor (RSENSE) at the CS pin. A linear dimming function can be accomplished by adjusting the current sense threshold voltage in the range of 0-250mV. When the linear dimming function is not used, it is recommended that the LD pin be connected to VDD. Figure 1 shows the functional block diagram of the MXHV9910 device. Figure 2 shows a schematic of a typical application circuit for the device, and is referred to in all the discussions that follow. MXHV9910 Block Diagram VDD VIN 6 1 Voltage Regulator Voltage Reference 250mV RT 8 OSC + LD 7 PWM Control 4 GATE 2 CS + PWMD 5 GND 3 AN-300-R00E www.clare.com 1 AN-300 Figure 2 Application Circuit Diagram D1 LEDs L1 VIN BR VIN VDD FUSE PWMD CC LD CVDD CBULK ROSC PGND RSENSE RT • DC Bulk Voltage at Low and High Line Typical Design Parameters Parameter AC Input Voltage Minimum Voltage Symbol Min Typ Max VAC-min 90 - - Maximum Voltage VAC-max - - 130 AC Input Frequency fac 50 - 60 Hz LED String Voltage VLEDstring - 60 - V LED String Current ILEDmax - - 350 mA Estimated Efficiency Oscillator Frequency η fS - 0.90 64 - kHz Dmax_spec - - 0.5 - Duty Cycle CS MXHV9910 NTC1 2 FET GATE V DC_bulk_min = Units 2 • V AC-min V DC_bulk_min = 127.3V Vrms V DC_bulk_max = 2 • V AC-max V DC_bulk_max = 183.8V • Average Input Current P in 23.33W I in_avg = ------------------------------- = -----------------V DC_bulk_min 127.3V I in_avg = 0.183A • Output Power Calculation • Peak Input Current P OUT = V LEDstring • I LEDmax I in_pk = 5 • I in_avg P OUT = 60V • 350mA I in_pk = 0.915A P OUT = 21W • Input Power Calculation P OUT P IN = ------------η 21W P IN = ----------0.90 Note: During a surge, the current could be as much as 5 times higher, hence the multiplier. P IN = 23.33W 2 www.clare.com R00E AN-300 3 Switching Frequency and Resistor RT Selection sets the internal RC oscillator frequency. For this design, RT is selected to be 402kΩ, which sets the oscillator frequency to about 64kHz. Figure 3 below shows the typical oscillator frequency for a given RT resistor value. It is recommended that the switching frequency range for off-line applications ranges from 30kHz to 120kHz. The MXHV9910 requires an external resistor, RT , that Figure 3 Oscillator Frequency vs. Resistor Value Oscillator Frequency, fS, vs. RT (TA=27ºC) 250 Frequency (kHz) 200 150 100 50 0 0 200 400 600 800 1000 1200 RT (kΩ) 4 Selecting Fuse and NTC1 Thermistor The fuse protects the circuit from input current surges during turn-on. Choose a fuse that is rated five times the peak input current. I fuse = 5 • I in_pk I fuse = 4.575A The thermistor in series with the input bridge rectifier limits the inrush charging current into the input bulk capacitor during startup. The value is determined by: The diode forward current rating should be set to 1.5 times the input average current. I fb = 1.5 • I in_avg I fb = 0.2745A The diode bridge can be subjected to currents as high as 5 times the forward current, and the diode bridge should be rated accordingly. I fsb = 5 • I fb I fsb = 1.3725A 2 • V AC_max R th_cold = ---------------------------------I in_pk R th_cold = 200.87Ω 5 Diode Bridge Rectifier The selection of the diode bridge rectifier is based on DC blocking voltage, forward current, and surge current. V rb = V DC_bulk_max V rb = 183.8V R00E www.clare.com 3 AN-300 6 Input Bulk Capacitor, CBULK, and CC The AC line voltage is filtered by the input bulk capacitor (CBULK), which is selected based on the minimum peak rectifier input line voltage and peak-topeak ripple voltage. Assuming a 20% ripple: 8 From the design requirements, the duty cycle and ON-time can be calculated as: V LEDstring 60V D max_buck = ------------------------------- = ----------------127.3V V DC_bulk_min r DC_bulk = 0.2 D max_buck = 0.471 V in_min = ( 1 – r DC_bulk ) • V DC_bulk_min = ( 1 – 0.2 ) × ( 127.3 ) D max_buck 0.471 t on.max_buck = ------------------------ = ---------------fS 64kHz V in_min = 101.8V P in C bulk = -----------------------------------------------------------------------------2 2 f AC • ( V DC_bulk_min – V in_min ) C bulk Duty Cycle and ON Time t on.max_buck = 7.366μs Dmax_buck is less than 50% and meets the subharmonic oscillation requirement. 23.33W = --------------------------------------------------------------------2 2 60Hz • ( 127.3V – 101.8V ) 9 C bulk = 66.70μF For this example, the voltage rating of the capacitor should be more than VDC_bulk_max with some safety margin factored in. An electrolytic capacitor with a 250V, 68μF rating would be adequate. Note that electrolytic bulk capacitors contain parasitic elements that cause their performance to be less than ideal. One important parasitic is the capacitor’s Equivalent Series Resistance (ESR), which causes internal heating as the ripple current flows into and out of the capacitor. In order to select a proper capacitor, the designer should consider capacitors that are specifically designed to endure the ripple current at the maximum temperature, and that have an ESR that is guaranteed within a specific frequency range (usually provided by manufacturers in the 120Hz to 100kHz range). The Effective Series Inductance (ESL) is another parasitic that limits the effectiveness of the electrolytic capacitor at high frequencies. The combination of the variation of ESR over temperature and a high ESL may require adding a parallel film or tantalum capacitor (CC) to absorb the high-frequency ripple component. This keeps the combined ESR within the required limit over the full design temperature range. 7 Inductor Design The inductor (L1) value is determined based on desired LED ripple current and the switching frequency. 64 kHz was chosen as the optimum switching frequency to minimize switching losses and to reduce circuit power dissipation at the expense of larger inductor size. Assuming a 30% peak-to-peak ripple in LED current, one can calculate the inductor requirements: r iout = 0.3 ( V DC_bulk_min – V LEDstring ) • t on.max_buck L min_buck = --------------------------------------------------------------------------------------------------r iout • I LEDmax ( 127.3V – 60V ) • 7.366μs L min_buck = ---------------------------------------------------------------0.3 • 350mA L min_buck = 4.7mH Inductor peak current rating: I Lmax = I LEDmax • ( 1 + ( 0.5 • r iout ) ) I Lmax = 350mA • ( 1 + ( 0.5 • 0.3 ) ) I Lmax = 0.403A In some cases, when the design requires a higher current rating and there is no standard inductor available, a custom-made inductor should be considered. Bypass Capacitor, CVDD The VDD pin is the internal regulator output pin and must be bypassed by a low-ESR capacitor (typically 0.1μF or higher) to provide a low-impedance path for high-frequency switching noise. 4 www.clare.com R00E AN-300 10 Power MOSFET and Diode Selection 11 Current Sense Resistor, RSENSE Peak voltage seen by the discrete power MOSFET (FET) and diode (D1) are equal to the maximum bulk voltage. For safety reasons assume an additional 50% margin by design. The current sense resistor (RSENSE) is selected based on the desired LED current. In this case, the maximum LED current is set at 350mA. Note that there is a difference between the peak current and the average current in the inductor. This ripple difference should be included in resistor calculations. The current sense threshold is given in the MXHV9910 data sheet. V FET_BVDSS_buck = 1.5 • V DC_bulk_max V FET_BVDSS_buck = 1.5 • 183.8V V FET_BVDSS_buck = 275.771V Assuming 30% ripple: V Diode_r_buck = 1.5 • V DC_bulk_max V cs(high) = 250mV V Diode_r_buck = 1.5 • 183.8V r iout = 0.3 V Diode_r_buck = 275.771V V cs(high) 250mV R sense = ------------------------------------------------------------------ = --------------------------------------------------------------( 1 + ( 0.5 • r iout ) ) • I LEDmax ( 1 + ( 0.5 • 0.3 ) ) • 350mA Maximum RMS current though the FET depends on the maximum duty cycle seen by the FET. In this buck converter, the maximum duty cycle is set slightly less than 50%. Choose a MOSFET with a rating of 3 times this current. I FET_rms_buck = 0.5 • I LEDmax I FET_rating_buck = 3 • I FET_rms_buck Note that since the current sense threshold voltage of the MXHV9910 (Vcsth) is specified between 200mV and 280mV, 250mV, the nominal value, is used in the formula above. Power dissipation across the sense resistor: I FET_rating_buck = 0.743A 2 Average current though the diode is one-half of the LED current. Choose a diode with a rating 3 times this current. P = I LEDmax • R sense P = 0.076W In practice, select a resistor power rating that is at least twice the calculated value. I Diode_buck = 0.5 • I LEDmax = 0.5 • 350mA = 0.175A I Diode_rating_buck = 3 • I Diode_buck I Diode_rating_buck = 0.525A 12 Layout Considerations For this design, the IXTA8N50P external power FET, in the SMD D2-Pak package, was selected from IXYS’ family of Polar N-channel devices. The Polar process features 30% reduction of RDS(on) and substantial reduction of total gate charge, QG. This helps with improved LED driver efficiency by minimizing conduction and switching losses. In addition, the Polar power FET family has very low thermal resistance, RθJC, which improves the device’s power dissipation. The IXA8N50P can be used with an external heat sink similar to Aavid Thermalloy’s part number 573100. The high frequency switching of the buck LED driver requires the use of a fast recovery diode. The BYV26_B series diode, in the SOD 57 package, was chosen for this design. R00E R sense = 0.621Ω In all switching converters, proper grounding and trace length are important considerations. The LED driver operates at a high frequency, and the designer must keep trace length from the MXHV9910 GATE pin to the external power MOSFET as short as possible. Doing this helps to avoid such undesired performance characteristics as ringing and spiking. In high-frequency switching, current tends to flow near the surface of a conductor, so ground traces on the PC board must be wide in order to avoid any problems due to parasitic trace inductance. If possible, one side of the PC board should be used as a ground plane. The current sense resistor, Rsense, should be kept close to the CS pin in order to prevent noise coupling to the internal high-speed voltage comparator, which would affect IC performance. In addition, RT should be placed away from the inductor and away from any PCB trace that is close to switching noise. www.clare.com 5 AN-300 13 Design Idea This design idea features an inexpensive, off-the-shelf Triac Dimmer Controller used with the MXHV9910 LED driver. The simple circuit is a voltage divider that feeds into the LD pin. The voltage divider can be adjusted for 110VAC or 220VAC operation simply by changing the value of resistor, R3. For a 220VAC application, decrease the value of R3 to 7.8kΩ. VIN TRIAC DIMMER CONTROLLER 120VAC EXT. POWER VIN FUSE F2 2A R1 402k AC AC X1 + VDD MONITOR LD MONITOR C1 0.01μF 400V D1 BYV26B df04s NTC1 R3 17k R4 10M 1 2 R5 100k L1 4.7mH 1 Q1 IXTA8N50P C2 2.2μF 16V MXHV9910 8-PIN SOIC 2 3 4 RT VIN DUT1 CS LD PGND VDD GATE PWMD 3 8 7 6 5 C3* 10μF LED+ pwmd LED CONNECTION LED- 1 R2 0.56Ω X2 2 3 PWMD * C3 can be between 0.1μF and 10μF For additional information please visit www.clare.com Clare, Inc. makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication and reserves the right to make changes to specifications and product descriptions at any time without notice. Neither circuit patent licenses or indemnity are expressed or implied. Except as set forth in Clare’s Standard Terms and Conditions of Sale, Clare, Inc. assumes no liability whatsoever, and disclaims any express or implied warranty relating to its products, including, but not limited to, the implied warranty of merchantability, fitness for a particular purpose, or infringement of any intellectual property right. The products described in this document are not designed, intended, authorized, or warranted for use as components in systems intended for surgical implant into the body, or in other applications intended to support or sustain life, or where malfunction of Clare’s product may result in direct physical harm, injury, or death to a person or severe property or environmental damage. Clare, Inc. reserves the right to discontinue or make changes to its products at any time without notice. Specifications: AN-300-R00E © Copyright 2009, Clare, Inc. All rights reserved. Printed in USA. 11/17/09 6 www.clare.com R00E