MIC4827_05 Datasheet, PDF (7/13 Pages) Micrel Semiconductor – Low Input Voltage, 180VPP Output Voltage, EL Driver

MIC4827
EL Frequency
The EL lamp frequency is controlled via an external resistor
connected between REL pin and VDD pin of the device. The
lamp frequency increases the resistor value decreases. For
resistor value selections, see the “Typical Characteristics: EL
Frequency vs. EL Resistor” or use the equation below. The
switching frequency range is 60Hz to 1000Hz, with an accu-
racy of ±20%.
f_EL (Hz)
=
360
R_EL (MΩ)
Micrel
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 fre-
quency.
V_IN = 3.0V
L = 220µH
C_OUT = 0.033µF
Lamp = 2in²
R_SW = 562k
R_EL = 1M
TIME (2ms/div)
Figure 3. 180Hz Output Waveform
TIME (2ms/div)
Figure 4. 360Hz Output Waveform
Enable Function
The enable function of the MIC4827 is implemented by
switching the R_SW and R_EL resistor between ground and V_DD.
When R_SW and R_EL are connected to ground, the switch and
the EL oscillators are disabled; therefore the EL driver be-
comes disabled. When these resistors connect to V_DD, both
the oscillators will function and the EL driver is enabled.
January 2005
7
MIC4827