Datasheet
Evaluates: MAX1739
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Lamp Current
R13 is an 85Ω resistor and sets the lamp current to
approximately 6mA
RMS
(entering the lamp). However,
the lamp current is dependent on the lamp characteris-
tics. Adjust R13 as needed to achieve the desired lamp
current for the CCFL of interest. Refer to the Sense
Resistors section of the MAX1739 data sheet for deter-
mining the values.
Inductor Tradeoffs
In order to achieve the narrow form factor required by
many of today’s notebook CCFL solutions, the EV kit
uses a small inductor. However, a 200µH inductor with
the same saturation current rating improves the input
transient response of the circuit.
MAX1739 Evaluation System/
Evaluation Kit
6 _______________________________________________________________________________________
Table 2. Jumper Settings Description
JUMPER
SHUNT
LOCATION
FUNCTION
1-2 MODE = REF (negative-scale ADC mode), CTL/SCL = 0 results in maximum brightness.
1-3 MODE = GND (positive-scale ADC mode), CTL/SCL = 0 results in minimum brightness.JU1
1-4 MODE = V
L
. Enable SMBus interface.
Open
Used for ADC mode. Drive CRF/SDA with an external voltage. The external voltage is the reference
input voltage for the ADC. (JU1 must be in the 1-2 or 1-3 position. JU5 = closed.)
1-2
Used for ADC mode. CRF/SDA = VL. VL is the reference input voltage for the ADC. (JU1 must be in
the 1-2 or 1-3 position. JU5 = closed.)
JU2
2-3 Used for SMBus mode: CRF/SDA connected to VL through a 10kΩ pullup resistor.
1-2 MINDAC = VL. Disables the DPWM chopping function.
1-3
MINDAC ≅ 1V. MINDAC is connected to REF through a voltage-divider formed by R1 and R2. This
voltage sets the DAC’s minimum scale output voltage.
JU3
1-4
MINDAC = 2V. MINDAC is connected to REF. This voltage sets the DAC’s minimum scale output
voltage.
1-2 Used for SMBus mode. SH/SUS is connected to VL through a 10kΩ pullup resistor.
JU4
2-3 Places the MAX1739 into shutdown.
Open Used for SMBus mode. Drive CRF/SDA with SMBus data.
JU5
Closed
Used for ADC mode. Drive CRF/SDA with analog voltage. (Connect JU2 to the 1-2 position to use
VL as the analog voltage.)
1-2
Used for ADC mode. CTL/SCL connected to the ADC reference input voltage (CRF/SDA) through
potentiometer R8. Adjusting R8 changes the brightness.
JU6
2-3 Used for SMBus mode. CTL/SCL connected to VL through a 10kΩ pullup resistor.
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Table 3. Jumper Settings Quick Reference
JUMPER
SMBUS
MODE
ADC
MODE
JU1 1-4 1-2 or 1-3
JU2 2-3 1-2
JU3 X X
JU4 1-2 1-2
JU5 Open Closed
JU6 2-3 1-2