LX1993CDUT [MICROSEMI]
暂无描述;
| 型号： | LX1993CDUT |
| 厂家： | 
Microsemi |
| 描述： | 暂无描述 驱动器 |
| 文件： | 总12页 (文件大小：454K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
KEY FEATURES
DESCRIPTION
> 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
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
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
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
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.
APPLICATIONS
Pagers
Wireless Phones
PDAs
Handheld Computers
LED Driver
Digital Camera Displays
selection
applications
of
battery
and start-up
voltage
is
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
PRODUCT HIGHLIGHT
SW
IN
OUT
SHDN
ON OFF
LX1993
Li-Ion
FB
CS
ADJ
GND
PACKAGE ORDER INFO
Plastic MSOP
8-Pin
DU
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
Page 1
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
ABSOLUTE MAXIMUM RATINGS
PACKAGE PIN OUT
Supply Voltage (VIN) ........................................................................-0.3V to 7.0V
Feedback Input Voltage (VFB) ................................................-0.3V to VIN + 0.3V
Shutdown Input Voltage (VSHDN)...........................................-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)
1
2
3
4
8
7
6
5
OUT
GND
CS
SW
IN
FB
SHDN
ADJ
DU PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
FRONT MARKING
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
.
1993
C
• MSC
THERMAL DATA
Plastic MSOP 8-Pin
DU
•
pin 1 indicator
THERMAL RESISTANCE
THERMAL RESISTANCE
-
-
JUNCTION TO
JUNCTION TO
A
C
MBIENT, θJA
ASE, θJC
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
N
AME
DESCRIPTION
Unregulated IC Supply Voltage Input – Input range from +1.6V to +6.0V. Bypass with a 1µF or greater capacitor
for low voltage operation.
IN
Feedback Input – Connect to a current sense resistor between the load and GND to set the maximum output
current.
FB
Active-Low Shutdown Input – A logic low shuts down the device and reduces the supply current to <1µA.
SHDN
SW
Connect
to VCC for normal operation.
SHDN
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.
GND
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.
ADJ
OUT
Output Current - Adjustable up to 25mA. Load voltage should not exceed 25V.
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Page 2
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
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.
LX1993
Typ
Parameter
Symbol
Test Conditions
Units
Min
Max
`
Operating Voltage
VIN
VSU
1.6
6.0
1.6
V
V
Minimum Start-up Voltage
Start-up Voltage Temperature
Coefficient
TA = +25°C
kVST
Guaranteed; not tested
-2
mV/°C
Not switching
70
0.2
300
100
0.5
325
100
VIN
µA
µA
mV
nA
V
nA
nA
V
Quiescent Current
IQ
V
SHDN < 0.4V
FB Threshold Voltage
FB Input Bias Current
VFB
IFB
VADJ
IADJ
ISHDN
VSHDN
VSHDN
ICS
IMIN
RDS(ON)
ILEAK
tOFF
VF
275
-100
0.0
-150
-100
1.6
Switching VADJ = 0.4V
ADJ Input Voltage Range
ADJ Input Bias Current
VADJ < 0.3V
VSHDN = 0V
50
100
Shutdown Input Bias Current
Shutdown High Input Voltage
Shutdown Low Input Voltage
Current Sense Bias Current
Minimum Peak Current
0.4
6
155
V
2
85
µA
mA
Ω
µA
ns
V
RCS = 0Ω
Internal NFET On-resistance
Switch Pin Leakage Current
Maximum Switch Off-Time
Diode Forward Voltage
1.1
0.23
300
1.0
TA = +25°C; ISW = 10mA; VFB = 1V
VSW = 25V
VFB = 1V
TA = +25°C; IF = 150mA
TA = +25°C; VR = 25V
100
500
Diode Reverse Current
IR
1.5
µA
SIMPLIFIED BLOCK DIAGRAM
FB
SW
A1
Control
Driver
OUT
GND
Reference
Logic
Logic
ADJ
50pF
2.5M
Ω
4µA
A2
CS
Shutdown
Logic
IN
SHDN
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Page 3
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
APPLICATION CIRCUITS
Typical LED Driver Applications
L1
VBAT = 1.6V to 6.0V
47
µ
H
1206 Case Size
C1
1
µ
F
SW
IN
OUT
SHDN
ON OFF
LX1993
FB
CS
ADJ
GND
RCS
1kΩ
VF = 3.6V typ.
RSET
15Ω
ILED = 20mA to 0mA
Figure 1 – LED Driver with Full-Range Dimming Via PWM Input
L1
VBAT = 1.6V to 6.0V
47µH
1206 Case Size
C1
1µF
SW
IN
OUT
SHDN
ON OFF
LX1993
FB
ADJ
CS
+
-
GND
RCS
1kΩ
VADJ = 0.3V to 0.0V
VF = 3.6V typ.
RSET
15Ω
I
LED = 20mA to 0mA
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
Page 4
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
APPLICATION INFORMATION
O
PERATING
T
HEORY
INDUCTOR
SELECTION AND OUTPUT CURRENT LIMIT
P
ROGRAMMING
The LX1993 is a PFM boost converter that is
Setting the level of peak inductor current to approximately
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.
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:
V
⎛
⎜
⎝
⎞
⎟
⎠
IN
I PEAK = I MIN
+
t +
(
I
SCALE
)
R
D
CS
L
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
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.
D
ESIGN EXAMPLE:
Determine IPEAK where VIN equals 3.0V and RCS equals
4.02KΩ using nominal values for all other parameters.
RSET. The voltage at the FB pin is the product of IOUT (i.e.,
the current through the LED chain) and RSET
.
⎛
⎜
⎝
⎞
⎟
⎠
3.0V
44mA
IPEAK =197mA+
×850ns+
(
)×4.02KΩ
V
⎡
⎤
⎥
47µ7
kΩ
ADJmax
R
=
⎢
⎣
I
SET
LEDmax
⎦
The result of this example yields a nominal IPEAK of
approximately 428mA.
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).
O
UTPUT 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
V
RIPPLE = ∆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:
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Page 5
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
APPLICATION INFORMATION
E
VALUATION BOARD
⎛
⎞
L
⎜
⎜
⎟
⎟
×
(
IPK × IOUT
)
The LXE1993 evaluation board is available from
COUT
⎝
⎠
Microsemi for assessing overall circuit performance. The
evaluation board, shown in Figure 3, is 3 by 3 inches (i.e.,
7.6 by 7.6cm) square and programmed to drive 2 to 4 LEDs
(provided). Designers can easily modify circuit parameters
to suit their particular application by replacing RCS (as
described in this section) RSET (i.e., R4) and LED load.
Moreover, the inductor, FET, and switching diode are easily
swapped out to promote design verification of a circuit that
maximizes efficiency and minimizes cost for a specific
∆VDROOP
=
(
VIN − 0.5
)
The output overshoot can be estimated as follows where the
0.5 value in the denominator is an estimate of the voltage
drop across the diode:
⎛
⎜
⎜
⎝
⎞
⎟
⎟
⎠
L
2
1
×
×
(
IPK − IOUT
)
2
COUT
∆VOVERSHOOT
=
(
VOUT + 0.5 − V
)
IN
application.
connections are described in Table 1.
The evaluation board input and output
D
ESIGN EXAMPLE:
Determine the VRIPPLE where IPK equals 200mA, IOUT
equals 13.0mA, L equals 47µH, COUT equals 4.7µF, VIN
equals 3.0V, and VOUT equals 13.0V:
The DC input voltage is applied to VBAT (not VCC)
however the LX1993 IC may be driven from a separate DC
source via the VCC input. The output current (i.e., LED
brightness) is controlled by adjusting the on-board
⎛
⎞
47µH
4.7µF
potentiometer.
The designer may elect to drive the
⎜
⎜
⎟
⎟
×
(
200mA ×12.8mA
)
⎝
⎠
brightness adjustment circuit from VBAT or via a separate
voltage source by selecting the appropriate jumper position
(see Table 2). Optional external adjustment of the output
LED current is achieved by disengaging the potentiometer
and applying either a DC voltage or a PWM-type signal to
the VADJ input. The PWM signal frequency should be
higher than 150KHz and contain a DC component less than
350mV.
∆VDROOP
=
≅ 2.0mV
(
13.0 − 0.5
)
⎛
⎞
47µH
4.7µF
2
1
⎜
⎜
⎟
⎟
×
×
(200mA −12.8mA
)
2
⎝
⎠
∆VOVERSHOOT
Therefore
=
≅18.4mV
(
13.0 + 0.5 − 3.0
)
,
VRIPPLE = 2.0mV + 18.4mV + 10mV = 30.4mV
The LX1993 exhibits a low quiescent current (IQ < 0.5µA:
typ) during shutdown mode. The SHDN pin is used to
exercise the shutdown function on the evaluation board.
This pin is pulled-up to VCC via a 10KΩ resistor.
Grounding the SHDN pin shuts down the IC (not the circuit
output). The output voltage (i.e., voltage across the LED
string) is readily measured at the VOUT terminal and LED
current is derived from measuring the voltage at the VFDBK
pin and dividing this value by 15Ω (i.e., R4). The factory
installed component list for this must-have design tool is
provided in Table 3 and the schematic is shown in Figure 4.
D
IODE SELECTION
A Schottky diode is recommended for most applications
(e.g., Microsemi UPS5817). The low forward voltage drop
and fast recovery time associated with this device supports
the switching demands associated with this circuit
topology. The designer is encouraged to consider the
diode’s average and peak current ratings with respect to the
application’s output and peak inductor current
requirements. Further, the diode’s reverse breakdown
voltage characteristic must be capable of withstanding a
negative voltage transition that is greater than VOUT
.
Efficiency Measurement Hint: When doing an efficiency
evaluation using the LX1993 Evaluation Board, VPOT
should be driven by a separate voltage supply to account for
losses associated with the onboard reference (i.e., the 1.25V
shunt regulator and 1KΩ resistor). This circuit will have
VBAT - 1.25V across it and at the higher input voltages the
1KΩ resistor could have as much as 4mA through it. This
shunt regulator circuitry will adversely effect the overall
efficiency measurement. It is not normally used in an
application; hence, it should not be considered when
measuring efficiency.
PCB LAYOUT
The LX1993 produces high slew-rate voltage and
current waveforms hence; the designer should take this into
consideration when laying out the circuit. Minimizing
trace lengths from the IC to the inductor, diode, input and
output capacitors, and feedback connection (i.e., pin 3) are
typical considerations. Moreover, the designer should
maximize the DC input and output trace widths to
accommodate peak current levels associated with this
topology.
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Page 6
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
APPLICATION INFORMATION (CONTINUED)
Figure 3: LXE1993 Engineering Evaluation Board
Table 1: Input and Ouput Pin Assignments
Pin Name
Allowable Range
Description
VBAT
0 to 6V
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.
VCC
VPOT
1.6V to 6V
1.6V to 6V
0 to 350mV
VADJ IN
/SHDN
VOUT
0 to VCC
0 to 18V
Pulled up to VCC on board (10KΩ), Ground to inhibit the LX1992.
Power supply output voltage that is applied to LED string.
VFDBK
0 to 400mV
Sense resistor voltage. Divide this voltage by 15 to determine LED current.
Table 2: Jumper Pin Position Assignments
Functional Description
Jumper Position
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/ BAT
VCC/ SEP
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.
VPOT/ VBAT
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.
VPOT/ SEP
ADJ/ POT
ADJ/ EXT
LED# OFF
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.
Note: Always put jumpers in one of the two possible positions
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division
Page 7
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
APPLICATION INFORMATION (CONTINUED)
Table 3: Factory Installed Component List for the LX1993 Evaluation Board
Part
Reference
Part
Number
Quantity
Description
Manufacturer
1
1
2
2
1
1
1
2
1
1
1
1
4
5
5
CR1
Rectifier, Schottky, 1A, 20V, Powermite Type SMT
Inductor, 47uH, 540mA, SMT
Microsemi
Toko
UPS5817
L1
C1, C2
C3, C4
R4
A920CY-470
CETMK325BJ475MN
GRM40X7R104M050
ERJ6ENF15R0
ERJ3EKF5903
ERJ3EKF1000
ERJ3EKF1003
ERJ3EKF1002
3352E-1-503
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
Taiyo Yuden
Murata
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Bourns
R3
R2
R6, R8
R1, R5
R7
VR1
Microsemi
Microsemi
Chicago Miniature
3M
LX432CSC
VR2
1PMT4114
LED1 - 4
JB1 - JB3
CMD333UWC
929647-09-36
929955-06
Header, 3 Pos Vertical Type
Jumper
3M
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
GND
C2
4.7µF
25V
C1
4.7µF
25V
VPOT
VCC
VOUT
CMD333UWC
CMD333UWC
C3
0.1µF
50V
IN
SW
VR2
20V
1W
1PMT4114
VCC
OUT
FB
SHDN
ADJ
GND
R1
10k
CS
LED4
LED3
CMD333UWC
CMD333UWC
ON
R2
100Ω
OFF
SHDN
VADJ
R3
590K
VFDBK
R4
15Ω
VADJ
R8
R5 10k
100K
C4
4.7µF
25V
VPOT
R6
100k
VR1
R7
LX432
50k
Figure 4 – LXE1993 Boost Evaluation Board Schematic
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Page 8
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
CHARACTERISTIC CURVES
365
340
315
290
265
240
215
19 0
0
1000
2000
3000
4000
R
(Ohms)
CS
Figure 5: Example of Peak Current versus RCS value
Conditions:
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
V
IN = 2.5V (bottom), 3.3V (middle) & 4.5V (top
)
@ TA = 25oC
85%
80%
75%
70%
65%
60%
55%
50%
90%
85%
80%
75%
70%
65%
60%
55%
50%
1
6
11
16
1
6
11
16
2 1
LED Current ( mA)
LED Current ( mA)
Figure 7: Efficiency vs. LED Output Current.
2 LED Configuration: VIN = 3.5V, L = 47µH, RCS = 100Ω
Note: Data taken from LXE1993 Evaluation Board
Figure 8: Efficiency vs. LED Output Current.
2 LED Configuration: VIN = 5.0V, L = 47µH, RCS = 100Ω
Note: Data taken from LXE1993 Evaluation Board
10 0 %
90%
80%
70%
60%
50%
10 0 %
90%
80%
70%
60%
50%
0
5
10
15
20
0
5
10
15
20
LED Current ( mA)
LED Current ( mA)
Figure 9: Efficiency vs. LED Output Current.
4 LED Configuration: VIN = 3.5V, L = 47µH, RCS = 100Ω
Note: Data taken from LXE1993 Evaluation Board
Figure 10: Efficiency vs. LED Output Current.
4 LED Configuration: VIN = 5.0V, L = 47µH, RCS = 100Ω
Note: Data taken from LXE1993 Evaluation Board
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Page 9
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
CHARACTERISTIC CURVES
1.4 0
1.3 0
1.2 0
1.10
1.10
1.0 0
0.90
0.80
1.0 0
0
25
50
75
0
25
50
75
Temperature oC
Temperature oC
Figure 11: R
DS(on)
vs. Temperature
Condition: VIN = 3.0V; ISW = 10mA
Figure 12: R
vs. Temperature
Condition: VIN = 5.0V; ISW = 10mA
DS(on)
14 5.0 0
14 0 . 0 0
13 5.0 0
13 0 . 0 0
12 5.0 0
7.00
6.00
5.00
4.00
3.00
0
25
50
75
0
25
50
75
Temperature oC
Temperature oC
Figure 13: IMIN versus Temperature.
Figure 14: ICS versus Temperature.
Condition: VIN = 3.0V
Condition: VIN = 3.0V
Figure 15: Start-Up Waveforms.
Condition: VIN = 3.6V, CH1 = VOUT, CH2 = VSW, CH4 = IL
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Page 10
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
PACKAGE DIMENSIONS
8-Pin Miniature Shrink Outline Package (MSOP)
DU
A
M
ILLIMETERS
I
MIN
.112
.114
–
NCHES
Dim
MIN
2.85
2.90
–
MAX
3.05
3.10
1.10
0.40
MAX
.120
.122
0.043
0.160
A
B
C
B
D
0.25
0.009
G
H
J
0.65 BSC
0.025 BSC
0.38
0.64
0.015
0.025
0.13
0.18
0.005
0.007
H
G
K
0.95 BSC
0.037 BSC
P
L
M
N
P
0.40
0.70
0.016
0.027
M
3°
3°
C
0.05
4.75
0.15
5.05
0.002
0.187
0.006
0.198
K
N
L
D
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.
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division
Page 11
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX1993
High Efficiency LED Driver
I N T E G R A T E D P R O D U C T S
P
RODUCTION
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
Page 12
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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