LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION KEY FEATURES DESCRIPTION guaranteed at 1.6V input. The LX1993 is capable of switching currents in excess of 300mA and the output current is readily programmed using one external current sense resistor in series with the LEDs. This configuration provides a feedback signal to the FB pin thus maintaining constant output current regardless of varying LED forward voltage (VF). The LX1993 provides an additional feature for simple dynamic adjustment of the output current (i.e., up to 100% of the maximum programmed current). Designers can make this adjustment by generating an analog reference signal or a PWM signal applied directly to the ADJ pin and any PWM amplitude is readily accommodated via a single external resistor. The LX1993 is available in the 8-Pin MSOP and thus requires a very small PCB area. > 80% Maximum Efficiency 70µA Typical Quiescent Supply Current Externally Programmable Peak Inductor Current Limit For Maximum Efficiency Logic Controlled Shutdown < 1µA Shutdown Current Dynamic Output Current Adjustment Via Analog Reference Or Direct PWM Input 8-Pin MSOP Package WWW . Microsemi .C OM The LX1993 is a high efficiency step-up boost converter that features a psuedo-hysteretic pulse frequency modulation topology for driving white or color LEDs in backlight or frontlight systems. Designed for maximum efficiency, reduced board size, and minimal cost, the LX1993 is ideal for PDA and digital camera applications. The LX1993 features an internal N-Channel MOSFET and control circuitry that is optimized for portable system design applications. The LX1993 promotes improved performance in battery-operated systems by operating with a quiescent supply current 70µA (typical) and a shutdown current of less than 1µA. The input voltage range is from 1.6V to 6.0V thus allowing for a broad selection of battery voltage applications and start-up is APPLICATIONS Pagers Wireless Phones PDAs Handheld Computers LED Driver Digital Camera Displays IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com PRODUCT HIGHLIGHT SW IN OUT SHDN Li-Ion ON OFF LX1993 FB CS ADJ GND LX1993 PACKAGE ORDER INFO Plastic MSOP DU 8-Pin TA (°C) RoHS Compliant / Pb-free Transition DC: 0432 0 to 70 LX1993CDU Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1993CDU-TR) Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 1 LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION PACKAGE PIN OUT Supply Voltage (VIN) ........................................................................-0.3V to 7.0V Feedback Input Voltage (VFB) ................................................-0.3V to VIN + 0.3V Shutdown Input Voltage (V SHDN ) ...........................................-0.3V to VIN + 0.3V Adjust Input Voltage (VADJ) ....................................................-0.3V to VIN +0.3V Output Voltage (VOUT).......................................................................-0.3V to 25V Switch Voltage (VSW) ........................................................-0.3V to (VOUT + 1.0V) Switch Current (ISW) .............................................................................500mArms Operating Junction Temperature.................................................................. 150°C Storage Temperature Range...........................................................-65°C to 150°C Peak Package Solder Reflow Temp. (40 second max. exposure) ... 260°C (+0, -5) SW 1 8 OUT IN 2 7 GND FB 3 6 CS SHDN 4 5 ADJ DU P ACKAGE (Top View) RoHS / Pb-free 100% Matte Tin Lead Finish Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of specified terminal. FRONT MARKING THERMAL DATA • DU Plastic MSOP 8-Pin THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA THERMAL RESISTANCE-JUNCTION TO CASE, θJC WWW . Microsemi .C OM ABSOLUTE MAXIMUM RATINGS • 1993 C MSC pin 1 indicator 206°C/W 39°C/W Junction Temperature Calculation: TJ = TA + (PD x θJC). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. FUNCTIONAL PIN DESCRIPTION NAME DESCRIPTION IN Unregulated IC Supply Voltage Input – Input range from +1.6V to +6.0V. Bypass with a 1µF or greater capacitor for low voltage operation. FB Feedback Input – Connect to a current sense resistor between the load and GND to set the maximum output current. SHDN Active-Low Shutdown Input – A logic low shuts down the device and reduces the supply current to <1µA. Connect SHDN to VCC for normal operation. SW Inductor Switching Connection – Internally connected to the drain of a 28V N-channel MOSFET. SW is high impedance in shutdown. CS Current-Sense Amplifier Input – Connecting a resistor between CS and GND sets the peak inductor current limit. Common terminal for ground reference. ADJ Output Current Adjustment Input – Provides the internal reference for the output current feedback. The signal input can be either a PWM signal or analog voltage allowing a dynamic output current adjustment. The signal should typically range from 500mV to GND, but is capable of an input up to VIN. Caution should be used not to exceed the device output current rating. OUT Output Current - Adjustable up to 25mA. Load voltage should not exceed 25V. Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 2 PACKAGE DATA GND LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION Parameter Symbol Test Conditions Min LX1993 Typ Max Units ` Operating Voltage Minimum Start-up Voltage Start-up Voltage Temperature Coefficient VIN VSU TA = +25°C kVST Guaranteed; not tested IQ Quiescent Current FB Threshold Voltage FB Input Bias Current ADJ Input Voltage Range ADJ Input Bias Current Shutdown Input Bias Current Shutdown High Input Voltage Shutdown Low Input Voltage Current Sense Bias Current Minimum Peak Current Internal NFET On-resistance Switch Pin Leakage Current Maximum Switch Off-Time Diode Forward Voltage Diode Reverse Current VFB IFB VADJ IADJ I SHDN V SHDN V SHDN ICS IMIN RDS(ON) ILEAK tOFF VF IR 1.6 6.0 1.6 -2 Not switching V SHDN < 0.4V 275 -100 0.0 -150 -100 1.6 Switching VADJ = 0.4V VADJ < 0.3V V SHDN = 0V RCS = 0Ω TA = +25°C; ISW = 10mA; VFB = 1V VSW = 25V VFB = 1V TA = +25°C; IF = 150mA TA = +25°C; VR = 25V 70 0.2 300 100 mV/°C 100 0.5 325 100 VIN 50 100 0.4 6 155 2 85 1.1 0.23 300 1.0 1.5 V V 500 µA µA mV nA V nA nA V V µA mA Ω µA ns V µA WWW . Microsemi .C OM ELECTRICAL CHARACTERISTICS Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C ≤ TA ≤ 70°C except where otherwise noted and the following test conditions: VIN = 3V, VFB = 0.3V, VADJ = 0.2V and SW pin has +5V through 39.2Ω, SHDN = VIN and CS = GND. SIMPLIFIED BLOCK DIAGRAM FB SW A1 Reference Logic ADJ 50pF Control Logic Driver GND 2.5M Ω CS Shutdown Logic IN Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 SHDN Page 3 ELECTRICALS 4µ A A2 Copyright © 2000 Rev. 1.0b, 2005-03-03 OUT LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION APPLICATION CIRCUITS WWW . Microsemi .C OM Typical LED Driver Applications L1 V BAT = 1.6V to 6.0V 47 µ H 1206 Case Size C1 1µ F SW IN O UT ON OFF SHDN LX1993 FB CS ADJ G ND R CS 1 kΩ V F = 3.6V typ. I LED = 20mA to 0mA R SET 15Ω Figure 1 – LED Driver with Full-Range Dimming Via PWM Input L1 V BAT = 1.6V to 6.0V 47 µ H 1206 Case Size C1 1µ F SW IN OUT ON OFF SHDN LX1993 FB CS ADJ V ADJ = 0.3V to 0.0V GND R CS 1 kΩ V F = 3.6V typ. I LED = 20mA to 0mA RS E T 15Ω Figure 2 – LED Driver with Full-Range Dimming Via Analog Voltage Input Note: The component values shown are only examples for a working system. Actual values will vary greatly depending on desired parameters, efficiency, and layout constraints. Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 4 APPLICATIONS + - LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION APPLICATION INFORMATION The LX1993 is a PFM boost converter that is optimized for driving a string of series connected LEDs. It operates in a pseudo-hysteretic mode with a fixed switch “off time” of 300ns. Converter switching is enabled as LED current decreases causing the voltage across RSET to decrease to a value less than the voltage at the VADJ pin. When the voltage across RSET (i.e., VFB) is less than VADJ, comparator A1 activates the control logic. The control logic activates the DRV output circuit that connects to the gate of the internal FET. The output (i.e., SW) is switched “on” (and remains “on”) until the inductor current ramps up to the peak current level. This current level is set via the external RCS resistor and monitored through the CS input by comparator A2. The LED load is powered from energy stored in the output capacitor during the inductor charging cycle. Once the peak inductor current value is achieved, the output is turned off (off-time is typically 300ns) allowing a portion of the energy stored in the inductor to be delivered to the load (e.g., see Figure 6, channel 2). This causes the output voltage to continue to rise across RSET at the input to the feedback circuit. The LX1993 continues to switch until the voltage at the FB pin exceeds the control voltage at the ADJ pin. The value of RSET is established by dividing the maximum adjust voltage by the maximum series LED current. A minimum value of 15Ω is recommended for RSET. The voltage at the FB pin is the product of IOUT (i.e., the current through the LED chain) and RSET. R V ⎤ = ⎡⎢ ADJmax ILEDmax⎥⎦ SET ⎣ Copyright © 2000 Rev. 1.0b, 2005-03-03 Setting the level of peak inductor current to approximately 2X the expected maximum DC input current will minimize the inductor size, the input ripple current, and the output ripple voltage. The designer is encouraged to use inductors that will not saturate at the peak inductor current level. An inductor value of 47µH is recommended. Choosing a lower value emphasizes peak current overshoot while choosing a higher value emphasizes output ripple voltage. The peak switch current is defined using a resistor placed between the CS terminal and ground and the IPEAK equation is: I PEAK = I MIN + ⎛⎜ V IN L ⎞⎟ t D + (I SCALE )R ⎝ ⎠ CS The maximum IPEAK value is limited by the ISW value (max. = 500mA rms). The minimum IPEAK value is defined when RCS is zero. The minimum IPEAK value is defined when RCS is zero. A typical value for the minimum peak current (IMIN) at 25oC is 197mA. The parameter tD is related to internal operation of comparator A. A typical value at 25oC is 850ns. A typical value of ISCALE at 25oC is 44mA per KΩ. All of these parameters have an effect on the final IPEAK value. DESIGN EXAMPLE: Determine IPEAK where VIN equals 3.0V and RCS equals 4.02KΩ using nominal values for all other parameters. ( ) ⎞ × 850ns + 44mA × 4.02KΩ IPEAK = 197mA+ ⎛⎜ 3.0V 47µ7 ⎟⎠ kΩ ⎝ The result of this example yields a nominal IPEAK of approximately 428mA. OUTPUT RIPPLE AND CAPACITOR SELECTION Output voltage ripple is a function of the inductor value (L), the output capacitor value (COUT), the peak switch current setting (IPEAK), the load current (IOUT), the input voltage (VIN) and the output voltage (VOUT) for a this boost converter regulation scheme. When the switch is first turned on, the peak-to-peak voltage ripple is a function of the output droop (as the inductor current charges to IPEAK), the feedback transition error (i.e., typically 10mV), and the output overshoot (when the stored energy in the inductor is delivered to the load at the end of the charging cycle). Therefore the total ripple voltage is VRIPPLE = ∆VDROOP + ∆VOVERSHOOT + 10mV The initial droop can be estimated as follows where the 0.5V value in the denominator is an estimate of the voltage drop across the inductor and the FET RDS_ON: Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 5 APPLICATIONS The application of an external voltage source at the ADJ pin provides for output current adjustment over the entire dimming range and the designer can select one of two possible methods. The first option is to connect a PWM logic signal to the ADJ pin (e.g., see Figure 1). The LX1993 includes an internal 50pF capacitor to ground that works with an external resistor to create a low-pass filter (i.e., filter out the AC component of a pulse width modulated input of fPWM ≥ 100KHz). The second option is to adjust the reference voltage directly at the ADJ pin by applying a DC voltage from 0.0 to 0.3V (e.g., see Figure 2). The adjustment voltage level is selectable (with limited accuracy) by implementing the voltage divider created between the external series resistor and the internal 2.5MΩ resistor. Disabling the LX1993 is achieved by driving the SHDN pin with a low-level logic signal thus reducing the device power consumption to approximately 0.5µA (typ). INDUCTOR SELECTION AND OUTPUT CURRENT LIMIT PROGRAMMING WWW . Microsemi .C OM OPERATING THEORY LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION APPLICATION INFORMATION EVALUATION BOARD Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 6 APPLICATIONS The LXE1993 evaluation board is available from Microsemi for assessing overall circuit performance. The ∆VDROOP evaluation board, shown in Figure 3, is 3 by 3 inches (i.e., (VIN − 0.5) 7.6 by 7.6cm) square and programmed to drive 2 to 4 LEDs The output overshoot can be estimated as follows where the (provided). Designers can easily modify circuit parameters 0.5 value in the denominator is an estimate of the voltage to suit their particular application by replacing RCS (as drop across the diode: described in this section) RSET (i.e., R4) and LED load. ⎛ ⎞ L Moreover, the inductor, FET, and switching diode are easily 2 1 ×⎜ ⎟ × (I PK − IOUT ) 2 ⎜ ⎟ swapped out to promote design verification of a circuit that C OUT ⎝ ⎠ ∆VOVERSHOOT = maximizes efficiency and minimizes cost for a specific (VOUT + 0.5 − VIN ) application. The evaluation board input and output DESIGN EXAMPLE: connections are described in Table 1. Determine the VRIPPLE where IPK equals 200mA, IOUT The DC input voltage is applied to VBAT (not VCC) however the LX1993 IC may be driven from a separate DC equals 13.0mA, L equals 47µH, COUT equals 4.7µF, VIN source via the VCC input. The output current (i.e., LED equals 3.0V, and VOUT equals 13.0V: brightness) is controlled by adjusting the on-board ⎛ 47µH ⎞ potentiometer. The designer may elect to drive the ⎟⎟ × (200mA × 12.8mA ) ⎜⎜ 4.7µF ⎠ brightness adjustment circuit from VBAT or via a separate ⎝ ∆VDROOP = ≅ 2.0mV (13.0 − 0.5) voltage source by selecting the appropriate jumper position (see Table 2). Optional external adjustment of the output ⎛ ⎞ µ 47 H 2 LED current is achieved by disengaging the potentiometer 1 ×⎜ ⎟ × (200mA − 12.8mA ) 2 ⎜ 4.7µF ⎟⎠ and applying either a DC voltage or a PWM-type signal to ⎝ ∆VOVERSHOOT = ≅ 18.4mV the VADJ input. The PWM signal frequency should be (13.0 + 0.5 − 3.0) higher than 150KHz and contain a DC component less than Therefore, VRIPPLE = 2.0mV + 18.4mV + 10mV = 30.4mV 350mV. The LX1993 exhibits a low quiescent current (IQ < 0.5µA: DIODE SELECTION typ) during shutdown mode. The SHDN pin is used to A Schottky diode is recommended for most applications exercise the shutdown function on the evaluation board. (e.g., Microsemi UPS5817). The low forward voltage drop This pin is pulled-up to VCC via a 10KΩ resistor. and fast recovery time associated with this device supports Grounding the SHDN pin shuts down the IC (not the circuit the switching demands associated with this circuit output). The output voltage (i.e., voltage across the LED topology. The designer is encouraged to consider the diode’s average and peak current ratings with respect to the string) is readily measured at the VOUT terminal and LED current is derived from measuring the voltage at the VFDBK application’s output and peak inductor current pin and dividing this value by 15Ω (i.e., R4). The factory requirements. Further, the diode’s reverse breakdown installed component list for this must-have design tool is voltage characteristic must be capable of withstanding a provided in Table 3 and the schematic is shown in Figure 4. negative voltage transition that is greater than VOUT. Efficiency Measurement Hint: When doing an efficiency PCB LAYOUT evaluation using the LX1993 Evaluation Board, VPOT The LX1993 produces high slew-rate voltage and should be driven by a separate voltage supply to account for current waveforms hence; the designer should take this into losses associated with the onboard reference (i.e., the 1.25V consideration when laying out the circuit. Minimizing shunt regulator and 1KΩ resistor). This circuit will have trace lengths from the IC to the inductor, diode, input and VBAT - 1.25V across it and at the higher input voltages the output capacitors, and feedback connection (i.e., pin 3) are 1KΩ resistor could have as much as 4mA through it. This typical considerations. Moreover, the designer should shunt regulator circuitry will adversely effect the overall maximize the DC input and output trace widths to efficiency measurement. It is not normally used in an accommodate peak current levels associated with this application; hence, it should not be considered when topology. measuring efficiency. WWW . Microsemi .C OM ⎛ L ⎞ ⎜⎜ ⎟⎟ × (I PK × I OUT ) C OUT ⎠ ⎝ = LX1993 I N T E G R A T E D P R O D U C T S High Efficiency LED Driver P RODUCTION APPLICATION INFORMATION (CONTINUED) WWW . Microsemi .C OM Figure 3: LXE1993 Engineering Evaluation Board Table 1: Input and Ouput Pin Assignments Allowable Range Description Pin Name VBAT 0 to 6V VCC 1.6V to 6V VPOT 1.6V to 6V VADJ IN 0 to 350mV /SHDN 0 to VCC Pulled up to VCC on board (10KΩ), Ground to inhibit the LX1992. VOUT 0 to 18V Power supply output voltage that is applied to LED string. VFDBK 0 to 400mV Jumper Position Main power supply for output. (Set external current limit to 0.5A) LX1993 power. May be strapped to VBAT or use a separate supply if VCC jumper is in the SEP position. Do not power output from VCC pin on board.. Potentiometer power. May be strapped to VBAT or use a separate supply if VPOT jumper is in the SEP position. Do not power output from VPOT pin on board. Apply a DC voltage or a PWM voltage to this pin to adjust the LED current. PWM inputs should be greater than 120Hz and DC portion less than 350mV. Sense resistor voltage. Divide this voltage by 15 to determine LED current. Table 2: Jumper Pin Position Assignments Functional Description VCC/ BAT Use this position when powering VBAT and VCC from the same supply. Do not connect power to the VCC input when using this jumper position. VCC/ SEP Use this position when using a separate VCC supply (different from VBAT). VPOT/ VBAT ADJ/ POT Use this position when using the potentiometer to adjust LED current. ADJ/ EXT Use this position when adjusting the LED current with an external PWM that has a repetition rate >120Hz. Or when using a DC adjustment voltage. LED# OFF Use this position to short out LED # 3 and / or LED # 4. Note: Always put jumpers in one of the two possible positions Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 7 APPLICATIONS VPOT/ SEP Use this position when powering the potentiometer reference circuit from the VBAT supply. Do not connect power to the VCC input when using this jumper position. Use this position when using a separate power supply (different from VBAT) to power the potentiometer reference circuit. This will lower the VBAT current and provide a more accurate efficiency reading for the LX1993 circuit. LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION APPLICATION INFORMATION (CONTINUED) Quantity Part Reference 1 CR1 1 L1 Description Part Number Manufacturer Rectifier, Schottky, 1A, 20V, Powermite Type SMT Microsemi UPS5817 Toko A920CY-470 Inductor, 47uH, 540mA, SMT 2 C1, C2 Capacitor, Ceramic X5R, 4.7uF, 25V, 1210 Type SMT Taiyo Yuden CETMK325BJ475MN 2 C3, C4 Capacitor, Ceramic X7R, 0.1uF, 50V, 0805 Type SMT Murata GRM40X7R104M050 1 R4 Resistor, 15 Ohm, 1/10W, 0805 Type SMT Panasonic ERJ6ENF15R0 1 R3 Resistor, 590K, 1/16W, 0603 Type SMT Panasonic ERJ3EKF5903 1 R2 Resistor, 100, 1/16W, 0603 Type SMT Panasonic ERJ3EKF1000 2 R6, R8 Resistor, 100K, 1/16W, 0603 Type SMT Panasonic ERJ3EKF1003 1 R1, R5 Resistor, 10K, 1/16W, 0603 Type SMT Panasonic ERJ3EKF1002 1 R7 Bourns 3352E-1-503 1 VR1 IC, Voltage Reference, 1.25 Volts, SOT23 Type SMT Microsemi LX432CSC 1 VR2 Diode, Zener, 20V, 1W Powermite Type SMT Microsemi 1PMT4114 Chicago Miniature CMD333UWC 3M 929647-09-36 Trimpot, 50K, 1/2W, Through Hole Type 4 LED1 - 4 White LED 5 JB1 - JB3 Header, 3 Pos Vertical Type WWW . Microsemi .C OM Table 3: Factory Installed Component List for the LX1993 Evaluation Board 5 Jumper 3M 929955-06 Note: The minimum set of parts needed to build a working power supply are: CR1, L1, C1, C2, R2, R4, U1. Evaluation board P/L subject to change without notice. CR1 UPS5817 L1 47µH VBAT VPOT VCC C2 4.7µF 25V C1 4.7µF 25V VOUT GND CMD333UWC C3 0.1µF 50V VCC IN SHDN R1 10k SW VR2 20V 1W 1PMT4114 OUT CMD333UWC ADJ FB GND CS LED4 LED3 R2 100Ω CMD333UWC ON OFF SHDN CMD333UWC VFDBK R3 590K VADJ APPLICATIONS R4 15Ω VADJ R5 10k C4 4.7µF 25V VPOT R8 100K R6 100k VR1 LX432 R7 50k Figure 4 – LXE1993 Boost Evaluation Board Schematic Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 8 LX1993 I N T E G R A T E D P R O D U C T S High Efficiency LED Driver P RODUCTION CHARACTERISTIC CURVES WWW . Microsemi .C OM 365 IPEAK (mA) 340 315 290 265 240 215 190 0 1000 2000 3000 4000 RCS (Ohms) Figure 5: Example of Peak Current versus RCS value Figure 6: VOUT and Inductor Current Waveforms. Channel 1: VOUT (AC coupled; 100mV/div) Channel 2: Inductor Current (100mA/div.) 4 LED Configuration: VIN = 3.0V 85% 90% 80% 85% 80% 75% Efficiency Efficiency Conditions: VIN = 2.5V (bottom), 3.3V (middle) & 4.5V (top) @ TA = 25oC 70% 65% 60% 75% 70% 65% 60% 55% 55% 50% 50% 1 6 11 LED C ur r ent ( mA ) 1 16 6 11 LED C ur r ent ( mA ) 16 21 Figure 8: Efficiency vs. LED Output Current. 2 LED Configuration: VIN = 5.0V, L = 47µH, RCS = 100Ω Note: Data taken from LXE1993 Evaluation Board 100% 100% 90% 90% Efficiency Efficiency Figure 7: Efficiency vs. LED Output Current. 2 LED Configuration: VIN = 3.5V, L = 47µH, RCS = 100Ω Note: Data taken from LXE1993 Evaluation Board 80% 70% 60% 70% 60% 50% 0 5 10 15 LED C ur r ent ( mA ) 20 Figure 9: Efficiency vs. LED Output Current. 0 5 10 15 LED C ur r ent ( mA ) CHARTS 50% 20 Figure 10: Efficiency vs. LED Output Current. 4 LED Configuration: VIN = 3.5V, L = 47µH, RCS = 100Ω Note: Data taken from LXE1993 Evaluation Board Copyright © 2000 Rev. 1.0b, 2005-03-03 80% 4 LED Configuration: VIN = 5.0V, L = 47µH, RCS = 100Ω Note: Data taken from LXE1993 Evaluation Board Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 9 LX1993 I N T E G R A T E D P R O D U C T S High Efficiency LED Driver P RODUCTION CHARACTERISTIC CURVES WWW . Microsemi .C OM RDS_on (Ohms) RDS_on (Ohms) 1.40 1.30 1.20 1.10 1.00 1.00 0.90 0.80 0 25 Temperature 50 75 0 o C 25 Temperature Figure 11: RDS(on) vs. Temperature Condition: VIN = 3.0V; ISW = 10mA 50 75 o C Figure 12: RDS(on) vs. Temperature Condition: VIN = 5.0V; ISW = 10mA 145.00 7.00 140.00 6.00 ICS (µ A) IMIN (mA) 1.10 135.00 130.00 5.00 4.00 125.00 3.00 0 25 Temperature 50 75 o C 0 25 Temperature Figure 13: IMIN versus Temperature. Condition: VIN = 3.0V 50 75 o C Figure 14: ICS versus Temperature. Condition: VIN = 3.0V CHARTS Figure 15: Start-Up Waveforms. Condition: VIN = 3.6V, CH1 = VOUT, CH2 = VSW, CH4 = IL Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 10 LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION DU 8-Pin Miniature Shrink Outline Package (MSOP) A Dim B H G P M C N Note: WWW . Microsemi .C OM PACKAGE DIMENSIONS D L K A B C D G H J K L M N P MILLIMETERS MIN MAX 2.85 3.05 2.90 3.10 – 1.10 0.25 0.40 0.65 BSC 0.38 0.64 0.13 0.18 0.95 BSC 0.40 0.70 3° 0.05 0.15 4.75 5.05 INCHES MIN MAX .112 .120 .114 .122 – 0.043 0.009 0.160 0.025 BSC 0.015 0.025 0.005 0.007 0.037 BSC 0.016 0.027 3° 0.002 0.006 0.187 0.198 Dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(0.006”) on any side. Lead dimension shall not include solder coverage. MECHANICALS Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 11 LX1993 I N T E G R A T E D High Efficiency LED Driver P R O D U C T S P RODUCTION NOTES WWW . Microsemi .C OM NOTES PRODUCTION DATA – Information contained in this document is proprietary to Microsemi and is current as of publication date. This document may not be modified in any way without the express written consent of Microsemi. Product processing does not necessarily include testing of all parameters. Microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time. Copyright © 2000 Rev. 1.0b, 2005-03-03 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 12