HV841
Pin Configuration and Description
Pin #
1
2
Name
C
1
V
DD
Function
Enable input signal for EL lamp 1. Logic high will turn ON the EL lamp 1 and logic low will turn it OFF. Refer to the
Function Table.
Input supply voltage pin.
External resistor connection to set both the switching MOSFET frequency and EL Lamp frequency. The external
resistor should be connected between this pin and the V
DD
pin. The EL lamp frequency is switching frequency
divided by 128.
3
R
SW-OSC
The switching frequency increases as the value of R
SW-OSC
decreases. A 470kΩ resistor will provide a switching
frequency of 31.2 kHz, and an EL lamp frequency of 244 Hz. To change the frequency to f
SW1
, the value of the
resistor R
SW-OSC1
can be determined as R
SW-OSC1
= (470k x 31.2k) / f
SW1
.
4
5
C
2
GND
Enable input signal for EL lamp 2. Logic high will turn ON the EL lamp 2 and logic low will turn it OFF. Refer to the
Function Table.
IC Ground Pin.
External inductor connection to boost the low input voltage using inductive flyback. Connect an inductor
between V
IN
and this pin. Also connect a high voltage fast recovery diode between this pin and the C
S
pin. The anode of the diode needs to be connected to the L
X
pin and the cathode to the C
S
pin. In general,
small valued inductors, which can handle more current, are more suitable for driving large sized lamps.
As the inductor value decreases, the switching frequency should be increased to avoid saturation.
When the switching MOSFET is turned ON, the inductor is being charged. When the MOSFET is turned OFF, the
energy stored in the inductor is transferred to the high voltage capacitor connected at the C
S
pin.
6
L
X
7
8
9
10
C
S
Com
EL
2
EL
1
Connect a 200V capacitor between this pin and GND. This capacitor stores the energy transferred from the
inductor.
Common connection for both EL lamps. Connect one end of both the lamps to this pin.
EL lamp 2 connection. For optimum performance, the smaller of the two lamps should be connected to this pin.
EL lamp 1 connection. For optimum performance, the larger of the two lamps should be connected to this pin.
5
NR033106
SUPERTEX [ Supertex, Inc ]
