LX1689
I N T E G R A T E D
P R O D U C T S
Third Generation CCFL Controller
P
RODUCTION
D
ATA
S
HEET
DESCRIPTION
KEY FEATURES
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Microsemi
.C
OM
The LX1689 is the latest generation
Direct Drive CCFL (Cold Cathode
Fluorescent Lamp) Controller. It uses
new circuit design techniques (patents
pending) and combines digital and linear
circuits with an advanced BiCMOS
process to create a more complete
controller in a small package.
When compared to the original
LX1686 design, identical module
applications use from 12 to 30 less
components. New functions and
enhancements have been added to make
the LX1689 even easier to use.
The on-chip PLL circuit used to
synchronize the digital dimming burst
frequency to the video frame rate, as
used in the LX1686, is replaced with a
programmable counter. This counter can
divide the video controller horizontal
sync pulse, other external clock source
or the internal chip clock source to
generate the burst frequency.
The brightness control input allows the
use of either a DC voltage or a PWM
input to simplify design. Programmable
polarity brightness control is retained,
except in the case of externally clocked
digital dimming. Two onboard LDO
regulators extend the input voltage range
of the IC up to 28 Volts without using
external circuitry as was required with our
previous controllers.
The LX1689
includes a new lamp strike detection
scheme that saves a package pin and three
external components. Internal circuits
monitor lamp current pulses at the I_SNS
input to determine if the lamp strikes and
if it stays ignited once operational.
Integrating full wave rectifiers for
each of three lamp inputs has significantly
reduced the lamp feedback component
count. In addition the controller features
include auto shutdown for open or broken
lamps, and a lamp fault detection with a
status reporting output.
3 to 28 Volt Single Fixed (±20%)
Supply Operating Range
Selectable Analog/Digital
Dimming Modes
Digital Dimming Can Synch to
External Or Internal Clocks
User Programmable Digital
Dimming Burst Frequency
252 mS Power On Delay
Flexible Lamp Current
Compensation Input
Open Lamp Shutdown and Fault
Output Indicator
“On Chip” Full Wave Lamp
Current & Voltage Rectifiers
20 Pin TSSOP Package
BENEFITS
Low Component Count /
Module Cost / Size
High “Nits/Watt” Efficiency
Operates Directly From 1 to 6
Li_Ion Cells
Lamp Current Compensation
Input Makes Indoor/Outdoor
And Wide Temperature Range
Applications Easy to Design
IMPORTANT:
For the most current data, consult
MICROSEMI’s
website:
http://www.microsemi.com
PRODUCT HIGHLIGHT
LX1689 CCFL Inverter Layouts Examples*
2.64in.
(67mm)
.397 in
.
(10mm)
Actual Inverter Size
OR
1.38in.
(35mm)
.870 in.
(22mm)
Actual Inverter Size
*As Shown in Figure 1 (Typical Application)
Bill of Materials
1
LX1689CPW
1
Transformer
1
Dual FET
2
Connectors
7
Resistors
9
Capacitors
21
Total Count
LX1689
LX1689
PACKAGE ORDER INFO
T
J
(°C)
0 to 70
-40 to 85
M
IN
V
DD
3V
3V
M
AX
V
DD
28V
28V
PW
Plastic TSSOP
20-PIN
LX1689CPW
LX1689IPW
Note: Available in Tape & Reel.
Append the letter “T” to the part number. (i.e. LX1689CPWT)
Copyright
2000
Rev. 1.0b, 2003-03-31
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
MICROSEMI [ MICROSEMI CORPORATION ]
