LX1688_06 Datasheet, PDF (1/16 Pages) Microsemi Corporation – Multiple Lamp CCFL Controller

RangeMAX™
LX1688
TM
®
Multiple Lamp CCFL Controller
PRODUCTION DATA SHEET
DESCRIPTION
The LX1688 is a fixed frequency, dual Safety and reliability features include a
current/voltage mode, switching regulator dual feedback control loop that permits
that provides the control function for Cold regulation of maximum lamp strike voltage
Cathode Fluorescent Lighting (CCFL). as well as lamp current. Regulating
This controller can be used to drive a maximum lamp voltage permits the designer
single lamp, but is specifically designed to provide for ample worst-case lamp strike
for multiple lamp LCD panels. The IC can voltage while conservatively limiting
be configured as a master or slave and maximum open circuit voltage. In addition
synchronize up to 12 controllers.
the controller features include auto
The LX1688 includes highly integrated shutdown for an open or broken lamp, and a
universal ‘PWM or DC’ dim input that lamp fault detection with a status reporting
allows either a PWM or DC input to adjust output.
brightness without requiring external To improve design flexibility the IC
conditioning, since a single external includes the ability to select the polarity of
capacitor CPWM can be used to integrate both the chip enable and dim (BRITE)
a PWM input. Burst mode dimming is inputs. Also included is a switched VDD
possible if the user supplies a low output of up to 10mA that will allow the
frequency PWM signal on the BRITE user to power other circuitry that can be
input and no CPWM capacitor is used. The switched on and off with the inverters
controller utilizes Microsemi’s patented enable input. This preserves the micro
direct drive fixed frequency topology and power sleep mode with no additional
patented resonant lamp strike generation components.
technique.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
Protected by U.S. Patents 5,615,093; 5,923,129; 5,930,121; 6,198,234; Patents Pending
DIMMING (BRITE)
ENABLE
PRODUCT HIGHLIGHT
LAMPS
INPUT
CONNECTOR
LX1688
MASTER
KEY FEATURES
ƒ Provision to Synchronize Lamp
Current & Frequency With Other
Controllers
ƒ Dimming With Analog or Digital
(PWM) Methods (>20:1)
ƒ Programmable Fixed Frequency
ƒ Adjustable Power-up Reset
ƒ ENABLE/BRITE Polarity Selection
ƒ Voltage Limiting on Step-up
Transformer Secondary Winding
ƒ Open Lamp Timeout Circuitry
ƒ Switched VDD Output (10mA)
ƒ Micro-Amp Sleep Mode
ƒ Operates With 3.3V to 5V Supply
ƒ 100mA Output Drive Capability
APPLICATIONS / BENEFITS
ƒ Desktop LCD Monitors
ƒ Multiple Lamp Panels
ƒ Low Ambient Light Displays
ƒ High Efficiency
ƒ Lower Cost than Conventional
Buck/Royer Inverter Topologies
ƒ Improved Lamp Strike Capability
ƒ Improved Over-Voltage Control
FAULT 1
FAULT 2
Copyright © 2001
Rev. 1.2, 2006-03-09
FAULT 1
ENABLE
BRITE
STRIKE
STATUS
125 Hz 5% Duty cycle Burst
65KHz run frequency
LX1688
SLAVE
VDD
FAULT 2
STRIKE
STATUS
Ch3 10.0mV Ω
Ch2
Simplified Quad Lamp Inverter Showing Synchronized Output Waveforms
10.0mV Ω
M100µs
T_J (°C)
0 to 70
-40 to 85
PACKAGE ORDER INFO
MIN V_DD
MAX V_DD
Plastic TSSOP
PW ^24-Pin
RoHS compliant / Pb-free Transition DC: 0442
3.0V
3.0V
5.5V
5.5V
LX1688CPW
LX1688IPW
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1688CPW-TR)
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
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