DS3881E+C Maxim Integrated Products, DS3881E+C Datasheet - Page 11

• Manufacturer Part Number: DS3881E+C
• Description: IC CCFL CONTROL 24TSSOP
• Manufacturer: Maxim Integrated Products
• Type: CCFL Controllerr

Specifications of DS3881E+C

• Frequency: 40 ~ 100 kHz
• Current - Supply: 12mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 24-TSSOP
• Operating Supply Voltage: 5 V
• Maximum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: + 105 C
• Supply Current: 12 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: DS3881E+; DS3881E+

Analog dimming changes the brightness by increasing
or decreasing the lamp current. The DS3881 accom-
plishes this by making small shifts to the lamp regula-
tion voltage, V
only possible by software communication with the lower
five bits (LC4–LC0) in the BLC register. This function is
not pin controllable. The default power-on state of the
LC bits is 00000b, which corresponds to 100% of the
nominal current level. Therefore on power-up, analog
dimming does not interfere with burst dimming func-
tionality if it is not desired. Setting the LC bits to 11111b
reduces the lamp current to 35% of its nominal level. For
LC values between 11111b and 00000b, the lamp cur-
rent varies linearly between 35% and 100% of nominal.
The DS3881 can generate its own lamp frequency
clock internally (set LFSS = 0 in CR1), which can then
be sourced to other DS3881s if required, or the lamp
clock can be supplied from an external source (set
LFSS = 1 in CR1). When the lamp clock is internally
generated, the frequency (40kHz to 100kHz) is set by
an external resistor at the LOSC. In this case, the
DS3881 can act as a lamp frequency source because
the lamp clock is output at the LSYNC I/O pin for syn-
chronizing any other DS3881s configured as lamp fre-
quency receivers. While DS3881 is sourcing lamp
frequency to other DS3881’s and spread-spectrum
modulation or frequency step features are enabled, the
LSYNC output is not affected by either EMI suppression
features. The DS3881 acts as a lamp frequency receiv-
er when the lamp clock is supplied externally. In this
case, a 40kHz to 100kHz clock must be supplied at the
Figure 3. DPWM Source Configuration Options
CONTROL VOLTAGE
ANALOG DIMMING
SIGNAL
DPWM
Single-Channel Automotive CCFL Controller
22.5Hz TO 440Hz
LRT
EXTERNAL RESISTOR
SETS DPWM RATE
(see Figure 2). Analog dimming is
RESISTOR-SET DIMMING CLOCK
0.5V
Lamp Frequency Configuration
2.0V
Analog Dimming
BRIGHT
PSYNC
POSC
____________________________________________________________________
LSYNC I/O. The external clock can originate from the
LSYNC I/O of a DS3881 configured as a lamp frequen-
cy source or from some other source.
The source and receiver options for the lamp frequency
clock and DPWM signal allow multiple DS3881s to be
synchronized in systems requiring more than 1 lamp.
The lamp and dimming clocks can either be generated
on board the DS3881 using external resistors to set the
frequency, or they can be sourced by the host system
to synchronize the DS3881 to other system resources.
Figure 5 shows various multiple DS3881 configurations
that allow both lamp and/or DPWM synchronization for
all DS3881s in the system.
Figure 4. DPWM Receiver Configuration
DPWM CLOCK
EXTERNAL
SIGNAL
DPWM
CONTROL VOLTAGE
ANALOG DIMMING
SIGNAL
DPWM
22.5Hz TO 440Hz
22.5Hz TO 440Hz
22.5Hz TO 440Hz
DPWM RECEIVER
0.5V
EXTERNAL DIMMING CLOCK
with Multiple DS3881s
Configuring Systems
2.0V
BRIGHT
PSYNC
POSC
BRIGHT
PSYNC
POSC
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