View LX1993CDU_665624.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

LX1993
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
DESCRIPTION
KEY FEATURES
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 70A (typical) and a shutdown current of less than 1A. 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
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 70A Typical Quiescent Supply Current Externally Programmable Peak Inductor Current Limit For Maximum Efficiency Logic Controlled Shutdown < 1A Shutdown Current Dynamic Output Current Adjustment Via Analog Reference Or Direct PWM Input 8-Pin MSOP Package 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 ADJ GND CS
LX1993 LX1993
PACKAGE ORDER INFO Plastic MSOP DU 8-Pin TA (C) 0 to 70 LX1993CDU
RoHS Compliant / Pb-free Transition DC: 0432
Note: Available in Tape & Reel. Append the letters "TR" to the part number. (i.e. LX1993CDU-TR)
Copyright (c) 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
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
ABSOLUTE MAXIMUM RATINGS
PACKAGE PIN OUT
SW IN FB SHDN 1 2 3 4 8 7 6 5 OUT GND CS ADJ
WWW .Microsemi .C OM
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.................................................................. 150C Storage Temperature Range...........................................................-65C to 150C Peak Package Solder Reflow Temp. (40 second max. exposure) ... 260C (+0, -5)
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.
DU PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
FRONT MARKING
THERMAL DATA
*
*
1993 C MSC
pin 1 indicator
DU
Plastic MSOP 8-Pin 206C/W 39C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, JA THERMAL RESISTANCE-JUNCTION TO CASE, JC
Junction Temperature Calculation: TJ = TA + (PD x JC). The JA 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 IN FB DESCRIPTION Unregulated IC Supply Voltage Input - Input range from +1.6V to +6.0V. Bypass with a 1F or greater capacitor for low voltage operation. Feedback Input - Connect to a current sense resistor between the load and GND to set the maximum output current. Active-Low Shutdown Input - A logic low shuts down the device and reduces the supply current to <1A. Connect SHDN to VCC for normal operation. Inductor Switching Connection - Internally connected to the drain of a 28V N-channel MOSFET. SW is high impedance in shutdown. Current-Sense Amplifier Input - Connecting a resistor between CS and GND sets the peak inductor current limit. Common terminal for ground reference. 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. Output Current - Adjustable up to 25mA. Load voltage should not exceed 25V.
SHDN
SW CS GND ADJ OUT
PACKAGE DATA PACKAGE DATA
Copyright (c) 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
LX1993
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
ELECTRICAL CHARACTERISTICS Unless otherwise specified, the following specifications apply over the operating ambient temperature 0C TA 70C except where otherwise noted and the following test conditions: VIN = 3V, VFB = 0.3V, VADJ = 0.2V and SW pin has +5V through 39.2, SHDN = VIN and CS = GND. Parameter
Operating Voltage Minimum Start-up Voltage Start-up Voltage Temperature Coefficient 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
WWW .Microsemi .C OM
Symbol VIN VSU kVST IQ VFB IFB VADJ IADJ I SHDN V SHDN V SHDN ICS IMIN RDS(ON) ILEAK tOFF VF IR
Test Conditions
Min 1.6
LX1993 Typ
Max 6.0 1.6
Units V V mV/C A A mV nA V nA nA V V A mA A ns V A
TA = +25C Guaranteed; not tested Not switching V SHDN < 0.4V Switching VADJ = 0.4V VADJ < 0.3V V SHDN = 0V -2 70 0.2 300
275 -100 0.0 -150 -100 1.6 2 85
100 0.5 325 100 VIN 50 100 0.4 6 155
RCS = 0 TA = +25C; ISW = 10mA; VFB = 1V VSW = 25V VFB = 1V TA = +25C; IF = 150mA TA = +25C; VR = 25V
100
1.1 0.23 300 1.0 1.5
500
SIMPLIFIED BLOCK DIAGRAM
FB
A1
SW
ADJ 50pF 2.5M
Reference Logic
Control Logic
Driver
OUT GND
ELECTRICALS ELECTRICALS
A2
4 A CS
IN
Shutdown Logic
SHDN
Copyright (c) 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 3
LX1993
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
APPLICATION CIRCUITS
WWW .Microsemi .C OM
Typical LED Driver Applications
L1
V BAT = 1.6V to 6.0V
47 H 1206 Case Size
C1 1 F SW
IN O UT
ON
OFF
SHDN
LX1993
FB ADJ G ND CS R CS 1 k
V F = 3.6V typ. I LED = 20mA to 0mA
Figure 1 - LED Driver with Full-Range Dimming Via PWM Input
L1
R SET
15
V BAT = 1.6V to 6.0V
47 H 1206 Case Size
C1 1F SW
IN OUT
ON
OFF
SHDN
LX1993
FB ADJ CS GND R CS 1 k RS E T
15
V ADJ = 0.3V to 0.0V V F = 3.6V typ. I LED = 20mA to 0mA
+ -
APPLICATIONS APPLICATIONS
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 (c) 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
LX1993
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
APPLICATION INFORMATION
WWW .Microsemi .C OM
OPERATING THEORY
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 15 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
INDUCTOR SELECTION AND OUTPUT CURRENT LIMIT PROGRAMMING
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 47H 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 K. All of these parameters have an effect on the final IPEAK value. DESIGN EXAMPLE: Determine IPEAK where VIN equals 3.0V and RCS equals 4.02K using nominal values for all other parameters.
x 850ns + 44mA x 4.02K IPEAK = 197mA+ 3.0V 477 k
(
)
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 2.5M 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 0.5A (typ).
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:
Page 5
APPLICATIONS APPLICATIONS
Copyright (c) 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
LX1993
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
APPLICATION INFORMATION
WWW .Microsemi .C OM
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 x x (I PK - IOUT ) 2 swapped out to promote design verification of a circuit that COUT 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 47H, COUT equals 4.7F, 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 47H potentiometer. The designer may elect to drive the x (200mA x 12.8mA ) 4.7F 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 47H 2 LED current is achieved by disengaging the potentiometer 1 x x (200mA - 12.8mA ) 2 and applying either a DC voltage or a PWM-type signal to 4.7F 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 < 0.5A: 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 10K 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 15 (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 1K 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 1K 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.
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
L x (I PK x I OUT ) C OUT =
EVALUATION BOARD
APPLICATIONS APPLICATIONS
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 6
LX1993
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
APPLICATION INFORMATION (CONTINUED)
WWW .Microsemi .C OM
Figure 3: LXE1993 Engineering Evaluation Board
Pin Name
VBAT VCC VPOT VADJ IN /SHDN VOUT VFDBK
Table 1: Input and Ouput Pin Assignments Allowable Range Description
0 to 6V 1.6V to 6V 1.6V to 6V 0 to 350mV 0 to VCC 0 to 18V 0 to 400mV 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. Pulled up to VCC on board (10K), Ground to inhibit the LX1992. Power supply output voltage that is applied to LED string. Sense resistor voltage. Divide this voltage by 15 to determine LED current.
Jumper Position
VCC/ BAT VCC/ SEP VPOT/ VBAT VPOT/ SEP ADJ/ POT ADJ/ EXT LED# OFF
Table 2: Jumper Pin Position Assignments Functional Description
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. Use this position when using a separate VCC supply (different from VBAT). 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. Use this position when using the potentiometer to adjust LED current. 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. Use this position to short out LED # 3 and / or LED # 4.
APPLICATIONS APPLICATIONS
Note: Always put jumpers in one of the two possible positions
Copyright (c) 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
LX1993
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
APPLICATION INFORMATION (CONTINUED)
WWW .Microsemi .C OM
Table 3: Factory Installed Component List for the LX1993 Evaluation Board
Quantity
1 1 2 2 1 1 1 2 1 1 1 1 4 5
Part Reference
CR1 L1 C1, C2 C3, C4 R4 R3 R2 R6, R8 R1, R5 R7 VR1 VR2 LED1 - 4 JB1 - JB3
Description
Rectifier, Schottky, 1A, 20V, Powermite Type SMT Inductor, 47uH, 540mA, SMT Capacitor, Ceramic X5R, 4.7uF, 25V, 1210 Type SMT Capacitor, Ceramic X7R, 0.1uF, 50V, 0805 Type SMT Resistor, 15 Ohm, 1/10W, 0805 Type SMT Resistor, 590K, 1/16W, 0603 Type SMT Resistor, 100, 1/16W, 0603 Type SMT Resistor, 100K, 1/16W, 0603 Type SMT Resistor, 10K, 1/16W, 0603 Type SMT Trimpot, 50K, 1/2W, Through Hole Type IC, Voltage Reference, 1.25 Volts, SOT23 Type SMT Diode, Zener, 20V, 1W Powermite Type SMT White LED Header, 3 Pos Vertical Type
Manufacturer
Microsemi Toko Taiyo Yuden Murata Panasonic Panasonic Panasonic Panasonic Panasonic Bourns Microsemi Microsemi Chicago Miniature 3M
Part Number
UPS5817 A920CY-470 CETMK325BJ475MN GRM40X7R104M050 ERJ6ENF15R0 ERJ3EKF5903 ERJ3EKF1000 ERJ3EKF1003 ERJ3EKF1002 3352E-1-503 LX432CSC 1PMT4114 CMD333UWC 929647-09-36
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.
L1 47H CR1 UPS5817
VBAT
VPOT VCC
C1 4.7F 25V C2 4.7F 25V
GND
VOUT
VCC
R1 10k
C3 0.1F 50V
CMD333UWC IN SHDN ADJ GND SW OUT CMD333UWC FB CS R2 100 CMD333UWC VR2 20V 1W 1PMT4114
LED4 LED3
ON OFF
SHDN
CMD333UWC R3 590K R4 15
VADJ
VADJ
R5 10k
VFDBK
APPLICATIONS APPLICATIONS
VPOT
R6 100k
C4 4.7F 25V
R8 100K
VR1 LX432
R7 50k
Figure 4 - LXE1993 Boost Evaluation Board Schematic
Copyright (c) 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
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
CHARACTERISTIC CURVES
WWW .Microsemi .C OM
365 340
IPEAK (mA)
315 290 265 240 215 190 0 1000 2000 3000 4000
RCS (Ohms)
Figure 5: Example of Peak Current versus RCS value
Conditions: VIN = 2.5V (bottom), 3.3V (middle) & 4.5V (top) @ TA = 25oC
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% 80%
90% 85% 80%
Efficiency
Efficiency
75% 70% 65% 60% 55% 50% 1 6 11 LED C ur r ent ( mA ) 16
75% 70% 65% 60% 55% 50% 1 6 11 LED C ur r ent ( mA ) 16 21
Figure 7: Efficiency vs. LED Output Current.
2 LED Configuration: VIN = 3.5V, L = 47H, RCS = 100 Note: Data taken from LXE1993 Evaluation Board
100% 90%
Figure 8: Efficiency vs. LED Output Current.
2 LED Configuration: VIN = 5.0V, L = 47H, RCS = 100 Note: Data taken from LXE1993 Evaluation Board
100% 90%
Efficiency
80% 70% 60% 50% 0 5 10 15 LED C ur r ent ( mA ) 20
Efficiency
80% 70% 60% 50% 0 5 10 15 LED C ur r ent ( mA ) 20
CHARTS CHARTS
Figure 9: Efficiency vs. LED Output Current.
4 LED Configuration: VIN = 3.5V, L = 47H, RCS = 100 Note: Data taken from LXE1993 Evaluation Board
Figure 10: Efficiency vs. LED Output Current.
4 LED Configuration: VIN = 5.0V, L = 47H, RCS = 100 Note: Data taken from LXE1993 Evaluation Board
Copyright (c) 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 9
LX1993
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
CHARACTERISTIC CURVES
WWW .Microsemi .C OM
1.40
RDS_on (Ohms)
1.30 1.20 1.10 1.00 0 25 50
o
RDS_on (Ohms)
75
1.10
1.00
0.90
0.80 0 25 50
o
75
Temperature
C
Temperature
C
Figure 11: RDS(on) vs. Temperature Condition: VIN = 3.0V; ISW = 10mA
Figure 12: RDS(on) vs. Temperature Condition: VIN = 5.0V; ISW = 10mA
145.00 140.00
7.00 6.00
IMIN (mA)
135.00 130.00 125.00 0 25 50
o
ICS ( A)
75
5.00 4.00 3.00 0 25 50
o
75
Temperature
C
Temperature
C
Figure 13: IMIN versus Temperature. Condition: VIN = 3.0V
Figure 14: ICS versus Temperature. Condition: VIN = 3.0V
CHARTS CHARTS
Figure 15: Start-Up Waveforms.
Condition: VIN = 3.6V, CH1 = VOUT, CH2 = VSW, CH4 = IL
Copyright (c) 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
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
PACKAGE DIMENSIONS
WWW .Microsemi .C OM
DU
8-Pin Miniature Shrink Outline Package (MSOP)
A
Dim A B C D G H J K L M N P
B
H
G P C N L K M
D
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
Note:
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 MECHANICALS
Copyright (c) 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
INTEGRATED PRODUCTS
High Efficiency LED Driver
PRODUCTION
NOTES
WWW .Microsemi .C OM
NOTES 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 (c) 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

▲Up To Search▲

Price & Availability of LX1993CDU

	To Download LX1993CDU Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .