DS3882E+C Maxim Integrated Products, DS3882E+C Datasheet - Page 10

• Manufacturer Part Number: DS3882E+C
• Description: IC CCFL CNTRLR DUAL 28TSSOP
• Manufacturer: Maxim Integrated Products
• Type: CCFL Controllerr

Specifications of DS3882E+C

• Frequency: 40 ~ 100 kHz
• Current - Supply: 12mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 28-TSSOP
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: Q3390330

Dual-Channel Automotive CCFL Controller
The DS3882 uses a push-pull drive scheme to convert
a DC voltage (8V to 16V) to the high-voltage (300V
to 1000V
the CCFLs. The push-pull drive scheme uses a minimal
number of external components, which reduces assem-
bly cost and makes the printed circuit board design
easy to implement. The push-pull drive scheme also
provides an efficient DC-to-AC conversion and pro-
duces near-sinusoidal waveforms.
Each DS3882 channel drives two logic-level n-channel
MOSFETs that are connected between the ends of a
step-up transformer and ground (see the Typical
Operating Circuit ). The transformer has a center tap on
the primary side that is connected to a DC voltage sup-
ply. The DS3882 alternately turns on the two MOSFETs
to create the high-voltage AC waveform on the sec-
ondary side. By varying the duration of the MOSFET
turn-on times, the CCFL current is able to be accurately
controlled.
A resistor in series with the CCFL’s ground connection
enables current monitoring. The voltage across this
resistor is fed to the lamp current monitor (LCM) input
and compared to an internal reference voltage to deter-
Figure 2. Per Channel Logic Diagram
10
512 X LAMP FREQUENCY
[20.48MHz ~ 51.20MHz]
DIMMING PWM SIGNAL
____________________________________________________________________
LAMP FREQUENCY
CHANNEL ENABLE
CHANNEL FAULT
RMS
[40kHz ~ 80kHz]
) AC waveform that is required to power
Detailed Description
CONTROLLER
DIGITAL
CCFL
64 LAMP CYCLE
INTEGRATOR
RMS
LAMP MAXIMUM VOLTAGE REGULATION
LAMP STRIKE AND REGULATION
mine the duty cycle for the MOSFET gates. Each CCFL
receives independent current monitoring and control,
which maximizes the lamp’s brightness and lifetime.
Block diagrams of the DS3882 are shown in Figures 1
and 2. More operating details of the DS3882 are dis-
cussed on the following pages of this data sheet.
The DS3882 uses an I
communication with the on-board EEPROM and SRAM
configuration/status registers as well as user memory.
The configuration registers, which are a mixture of
shadowed EEPROM and SRAM, allow the user to cus-
tomize many DS3882 parameters such as the soft-start
ramp rate, the lamp and dimming frequency sources,
brightness of the lamps, fault-monitoring options, chan-
nel enabling/disabling, EMI control, and lamp current
overdrive control. The eight bytes of NV user memory
can be used to store manufacturing data such as date
codes, serial numbers, or product identification num-
bers. The device is shipped from the factory with the
configuration registers programmed to a set of default
configuration parameters. To inquire about custom pro-
gramming, contact the factory.
LOCE BIT IN CR1.0
Functional Diagrams (continued)
OVERVOLTAGE
LAMP OVERCURRENT
I 2 C-Compatible Serial Interface
LAMP OUT
Memory Registers and
2
C-compatible serial interface for
300mV
2.5V
1.0V
V
LRT
DRIVERS
GATE
(1.0V NOMINAL)
OVDn
OVERVOLTAGE DETECTOR
LCMn
LAMP CURRENT
MONITOR
GAn
GBn
DRIVERS
MOSFET
GATE