LX1691B
TM
廬
Enhanced Multi-Mode CCFL Controller
P
RELIMINARY
D
ATA
S
HEET
DESCRIPTION
The LX1691B is an enhanced Direct modes that control lamp current amplitude
Drive CCFL (Cold Cathode Fluorescent and duty cycle simultaneously or separately.
Lamp) Controller. Its architecture is based on Designers can select normal or reverse
the LX1691. The LX1961B is optimized for polarity dimming and precisely program
wide input voltage applications. It is similar minimum and maximum lamp currents with
to the LX1691 except it has a guaranteed resistors. Fault protection includes open
minimum lamp strike interval of one second
1
lamp voltage regulation and shutdown for
to meet notebook and monitor panel over voltage and over current conditions.
manufacturer鈥檚 specifications.
The 鈥淏鈥?The LX1691B employs Microsemi鈥檚 proven
version also adds feed forward input voltage and patented strike method that allows
sensing to enhance transient response when significant
efficiency
gains
while
used in inverters that derive lamp power guaranteeing strong striking power at all
from unregulated input supplies and operating temperatures.
Our method
batteries.
sweeps strike frequency smoothly up to the
The LX1691B can also be used with unloaded resonant frequency of the lamp
fixed input supplies where it produces and high voltage transformer. This, coupled
performance equal to the LX1691.
with the LX1691B鈥檚 active high output
LX1691B based inverter modules can be voltage regulation, produces just enough
designed for virtually any CCFL appliance strike
voltage
without
generating
from digital cameras and PDA鈥檚 to big unpredictable high voltage spikes that cause
screen monitors and driver viewable arcing and component failures. Competitive
automotive displays.
devices that simply switch to a higher
New versatile dimming circuitry can
frequency for striking do not have this 鈥渞eal
accept digital and analog control inputs and
time鈥?control over output voltage, and
provides six different dimming
require much more attention to transformer
design.
IMPORTANT:
For the most current data, consult
MICROSEMI鈥檚
website:
http://www.microsemi.com
KEY FEATURES
Wide Input Voltage Capable
Simultaneous Amplitude And
Duty Cycle Dimming Modes
Resistor programmable min
and max lamp currents
Digital Dimming Can Synch To
External Or Internal Clocks
120 ms Power On Delay
Open Or Shorted Lamp
Regulation & Shutdown
鈥淥n Chip鈥?Full Wave Lamp
Current Rectifier
16 Pin TSSOP Package
Very Stable Oscillator with On-
Chip timing capacitor
Enhanced Digital Dimming
Resolution
BENEFITS
Low Component Count /
Module Cost / And Size
High 鈥淣its/Watt鈥?Efficiency
Can Operate Directly From a
Single Li-Ion Cell
Industries Safest And Highest
Performing Strike Voltage
Generation (Patented)
Tight Operating Frequency
Tolerance For Easier System
Level RFI Control
WWW .
Microsemi
.C
OM
Protected by U.S. Patents: 5,615,093; 5,923,129; 5,930,121; 6,198,234; Patents Pending
PRODUCT HIGHLIGHT
Traditional Analog
2
Lamp Current (mA)
+
External Digital
2
Lamp Current (mA)
+
BRITE_IN
+3V
T2
BRITE_IN
VDC
0
T1
DD_CLK
T1
VDC
0
_
T2
T
DD_CLK
T = 512 / DD_CLK Frequency
T
_
Internal Digital
2
Lamp Current (mA)
+
Direct PWM (Analog)
2
Lamp Current (mA)
BRITE_IN
+3V
T
+
BRITE_IN
VDC
0
DD_CLK
T
VDC
_
0
T1
T2
DD_CLK
T1
T = 256 / Lamp Frequency
_
T2
LX1691B
LX1691B
Four of Six Dimming Modes
PACKAGE ORDER INFO
T
A
(擄C)
-40 to +85
M
IN
V
DDP
2.8V
M
AX
V
DDP
5.5V
PW
Plastic TSSOP
16-PIN
LX1691BIPW
RoHS compliant / Pb-free
Note: Available in Tape & Reel. Append the letters 鈥淭R鈥?to the part number. (i.e. LX1691BIPW-TR)
1
If the lamp frequency is less than 115Khz.
Copyright
漏
2005
Rev. 0.4a, 3/8/2005
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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