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SLUS485A – JULY 2001 – REVISED NOVEMBER 2001
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FEATURES
APPLICATIONS
D
D
D
D
Synchronous or Nonsynchronous Operation
Dual Output and Control Stages
BiCMOS Technology
D
D
D
Portable PCs
Desktop LCD Monitors
Internet Appliances
Accurate Current Control with 2-mA Typical
Supply Current
DESCRIPTION
D
D
D
D
Analog or Digital Low-Frequency Dimming
Capability
Design goals for a cold cathode fluorescent lamp
(CCFL) converter used for a liquid crystal display
(LCD) monitor application include small size, high
efficiency, and low cost. The UCC2974/UCC3974
CCFL controllers provide the necessary circuit
blocks to implement a highly efficient LCD monitor
backlight supply in a small 16-pin TSSOP
package. The device features two control stages
for operating independent resonant tanks for
multi-lamp designs. The BiCMOS controller
typically consumes less than 2-mA of operating
current, improving overall system efficiency.
External parts count is minimized and system cost
is reduced by integrating such features as dual
PWM driver stages, open lamp protection,
overvoltage clamp, and synchronization circuitry
between the buck and push-pull stages. The
device operates in both analog and low-frequency
dimming modes.
Open Lamp Protection with Voltage Clamp
4.5-V to 25-V Operation
PWM Frequencies Synchronized to External
Resonant Tanks
D
TSSOP-16 (PW) Package
TYPICAL APPLICATION
VIN
VIN
VIN
UCC3974
OUT1
1
2
3
4
5
6
7
OUT2 16
GND 15
VIN
BUCK1
COMP1
FB1
BUCK2 14
CBP 13
COMP2 12
FB2 11
RC
RD
MODE 10
BRIGHT
SYNC
8
DIM
LFDSYNC
9
UDG–01023
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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Copyright 2001, Texas Instruments Incorporated
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