mic4830yml Micrel Semiconductor, mic4830yml Datasheet - Page 7

• Manufacturer Part Number: mic4830yml
• Description: Mic4830 Low Noise 180vp-p El Driver
• Manufacturer: Micrel Semiconductor

Switching Frequency
The switching frequency of the converter is
controlled via an external resistor between R
and V
increases as the resistor value decreases. For
resistor
Characteristics:
Resistor” or use the equation below. The switching
frequency range is 65kHz to 250kHz, with an
accuracy of ±20%.
switching frequency, the greater the input current is
drawn to deliver more power to the output.
However, the switching frequency should not be so
low as to allow the voltage at the switch node or the
CS pin to go beyond the absolute maximum voltage
of those pins.
EL Frequency
The EL lamp frequency is controlled via an external
resistor connected between R
the device. The lamp frequency increases as the
resistor
selections, see the “Typical Characteristics: EL
Frequency vs. EL Resistor” graph on page 4 or use
the equation below. The EL lamp frequency range is
60Hz to 1000Hz, with an accuracy of ±20%.
Micrel
November 2007
DD
f
f
pin of the device. The switching frequency
SW
EL
value
Figure 2. 100Hz Output Waveform
value
( )
Hz
(kHz)
=
decreases.
Switching
R
=
selections,
EL
R
Time (2ms/div)
360
SW
(
M
In general, the lower the
36
Ω
(
M
)
Ω
)
Frequency
EL
For
see
pin and V
resistor
the
vs.
DD
V
I
L = 220µH
C
LAMP = 2 in
R
R
IN
“Typical
IN
OUT
SW
EL
= 12mA
SW
= 3.6V
pin of
= 2.82M
value
= 250k
= 2.7nF
SW
pin
2
In general, as the EL lamp frequency increases, the
amount of current drawn from the battery will
increase. The color of the EL lamp and the intensity
are dependent upon its frequency.
Enable Function
The MIC4830 is disabled by connecting the external
resistor (Rsw) to GND.
oscillator of the boost converter.
external resistor (Rsw) to V
and turns on the device. The enable voltage should
rise or fall monotonically without interruption.
7
Figure 3. 200Hz Output Waveform
Figure 4. 300Hz Output Waveform
Time (2ms/div)
Time (2ms/div)
This turns off the switch
DD
enables the oscillator
Connecting the
M9999-111507-B
V
I
V
I
L = 220µH
C
LAMP = 2 in
R
R
L = 220µH
C
LAMP = 2 in
R
R
IN
IN
IN
IN
OUT
SW
EL
OUT
SW
EL
= 19mA
= 25mA
= 3.6V
= 3.6V
= 1.69M
= 1.1M
= 290k
= 352k
= 2.7nF
= 2.7nF
MIC4830
2
2