HV835 Datasheet, PDF (5/6 Pages) Supertex, Inc – Low Noise Dual EL Lamp Driver

HV835
Split Supply Configuration
The HV835 can be used in applications operating from a
battery where a regulated voltage is available. This is shown
in Figure 2. The regulated voltage can be used to drive the
internal logic of HV835. The amount of current used to drive
the internal logic is less than 200µA. Therefore, the regu-
lated voltage could easily provide the current without being
loaded down.
Figure 2 - Split Supply Configuration
V_EN = ON
0 = OFF
V_EN = ON
0 = OFF
Regulated Voltage = V_DD
C_DD
Battery Voltage = V_IN
R_SW-OSC
1 _C1
2 _VDD
3
R_SW-OSC
4
C₂
5
GND
10
EL₁
EL₂ ⁹
8
Com
C_S ⁷
L_X ⁶
HV835K7-G
C_IN
EL Lamp 1
EL Lamp 2
D
L_X
C_S
Pin Configuration and Description
Pin #
1
2
3
4
5
Function
C₁
V_DD
R
SW-OSC
C₂
GND
Description
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 voltage supply pin.
External resistor connection to set both the switching MOSFET frequency and EL Lamp frequency. The
external resistor should be connected between V_DD and this pin. The EL lamp frequency is the switch-
ing frequency divided by 512. The switching frequency is inversely proportional to the resistor value.
A 845kΩ resistor will provide a nominal switching frequency of 102kHz and an EL lamp frequency of
200Hz. To change the frequency to f_EL1, the value of the resistor R_SW-OSC1 can be determined as R_SW-OSC1
= (845 x 200) / f_EL1 kΩ.
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.
Device ground.
Drain of internal switching MOSFET. Connection for an external inductor. When the switching MOSFET
6
L_X 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.
7
C_S
Connect a 100V capacitor between this pin and GND. This capacitor stores the energy transferred from
the inductor.
8
COM Common lamp connection for both EL₁ and EL₂. Connect one end of both the lamps to this pin.
9
EL₂
EL lamp 2 connection. For optimum performance, the smaller of the two lamps should be connected
to this pin.
10
EL₁
EL lamp 1 connection. For optimum performance, the larger of the two lamps should be connected to
this pin.
5