MP1038 – FULL BRIDGE CCFL CONTROLLER
PIN FUNCTIONS
For TSSOP28 and SOIC28 devices
Pin #
Name
Description
1
SI
Secondary Current Feedback Input. Connect a current sense resistor from the cold end of
the secondary winding to ground. Connect this pin to the junction of the resistor and the
secondary winding. If the voltage at SI exceeds +1.2V, a pulse of current will pull down on
the COMP pin to attempt to regulate the secondary current and the Fault Timer will be
started.
2
3
LI
Lamp Current Feedback Input. Connect this pin to the cold end of the lamp and shunt a
sense resistor to ground. The sense amplifier will sink a current from the COMP pin
proportional to the absolute value of the voltage at this pin. (In regulation the average of the
absolute value of the voltage at this pin is determined by the voltage at the ABRT pin).
LV
Lamp Voltage Feedback Input. Connect a capacitive voltage divider from the hot end of the
lamp to ground. Connect this pin to the tap on the divider and shunt a bias resistor to
ground. If the voltage at LV exceeds +1.2 V, a pulse of current will pull down on the COMP
pin to attempt to regulate the lamp voltage and the Fault Timer will be started.
4
5
6
7
COMP
AG
Feed back Compensation Node. Connect a compensation capacitor from this pin to ground.
Analog Ground.
FT
Fault Timing. Connect a timing capacitor from this pin to AG to set the fault timeout period.
LCS
Lamp operating Clock Set. Connect a resistor from this pin to AG. This resistor sets the
operating frequency of the MP1038.
8
LCC
Lamp Clock Control. LCC provides compensation when the operating clock is swept in order
to strike the lamp. Connect a resistor in series with a capacitor from LCC to AG. Connect a
smaller capacitor directly from LCC to AG. Connect only a single capacitor to AG, if some
sweeping of the operating clock can be tolerated during open lamp conditions. Connect LCC
to AG to force the operating clock to the selected value at all times.
9
BRC
BRS
Burst Repetition rate Control. BRC provides compensation when the burst repetition rate is
to be synchronized to an external clock. Connect a resistor in series with a capacitor from
BRC to AG. Connect a smaller capacitor directly from BRC to AG. If the burst repetition rate
is not to be synchronized to an external clock, connect BRC to AG.
10
Burst Repetition rate Setting. If the burst repetition rate is to be synchronized to an external
clock, connect a capacitor from BRS to AG. If the burst rate generator is free-run and not be
synchronized with an external clock, connect a resistor in parallel with a capacitor from BRS
to AG. If the burst is to be controlled by an external logic signal, connect BRS to VCC and
apply the logic signal to the DBRT pin.
11
DBRT
ABRT
Burst-Mode (Digital) Brightness Control Input. The voltage range of 0V to 1.2V at DBRT
linearly sets the burst-mode duty cycle from minimum 10% to 100%. If burst dimming is not
used tie DBRT to VCC.
12
13
Analog Brightness Control Input. The voltage range of 0V to 1.2V at ABRT sets 3:1 dimming
range for the lamp current. If analog dimming is not used, tie ABRT to VCC.
ENSYNC Enable and Sync Composite Input. Pull ENSYNC high to turn on the MP1038, pull ENSYNC
low to turn it off. To synchronize the burst repetition rate to an external clock, apply the
synchronizing clock signal with low-going pulse width of 1-10us to this pin. Once the
MP1038 has aligned the burst oscillator to the sync signal, each burst will start at the low-
going edge of the sync pulse.
14
15
LOK
Lamp OK Flag Output (open drain). Connect this pin to a pull-up resistor to logic high. This
pin will not be activated during normal operation (including burst mode) nor when the
MP1038 is disabled. This pin will be pulled low when a fault (open lamp or secondary
over-current) is detected.
PRR
Input Power Rail, Right-Side. Connect PRR directly to the drain of the high-side, right-side,
external power MOSFET.
10/07, Rev. 1.4
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