MC33441 데이터 시트보기 (PDF) - Motorola => Freescale
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MC33441 Datasheet PDF : 12 Pages
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MC33441
APPLICATION INFORMATION
EL Lamp Selection
EL lamps are a laminate which exhibit a capacitance on
the order of 2.5nF to 3.5nF per square inch. The light will emit
as the high voltage is applied across the electrodes of this
capacitance. The color of the emitted light is determined by
the type of chemical used and the frequency of the excitation
voltage. On the other hand, the lamp brightness increases
approximately the square of the applied voltage and nearly
linear to the excitation frequency. Once a lamp has been
selected, the operating frequency and the essential voltage
for the optimum performance is determined. Then, the driver
circuit can begin to design.
Inductor Selection (L1)
Use a 1mH/0.15A inductor for MC33441. Higher inductor
values can be used to reduce the peak transient coil current
from the battery supply. As the value of the inductor (L1),
increases, the resistor (R1) value may need to increase
correspondingly to provide optimum performance. While a
lower inductor values lead to smaller physical size, it will
generate a higher peak coil current. A lower resistor (R1)
value should be used when a lower inductance coil is being
used.
The inductor must have a saturation current rating equal to
or bigger than the peak coil current which is 150mA.
Filter Capacitor Selection (C2)
See Table 1 for the estimated value of the filter capacitors
based on the input voltage supply. Since the maximum
voltage of the filter capacitor can reach 70V or even 80V,
capacitor with high voltage rating will be required.
Resistor Selection (R1)
Since the fundamental frequency of the oscillator is set by
the external resistor (R1), the temperature coefficient of the
frequency is dominated by the value of this resistor. A low
temperature coefficient (TC) resistor is suggested to use for
keeping the variation of oscillator’s frequency low against the
operation temperature range. (See Page 4, Fig. 3 & Fig. 4)
+ + W R1
REXT
4.341 107
FEL
Layout
The MC33441 is high output voltage operation make PC
board layout critical to minimize ground bounce and noise.
Locate input bypass capacitor, filter capacitor and oscillator’s
resistor as close to the device pins as possible.
MOTOROLA ANALOG IC DEVICE DATA
7
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