HV861
Pin Configuration and External Component Description
Pin #
Name
Description
External resistor from REL-Osc to VDD sets the EL frequency. The EL frequency is inversely pro-
portional to the external REL resistor value. Reducing the resistor value by a factor of two will result
in increasing the EL frequency by two.
1
REL-Osc
fEL = (2.0MΩ • 190Hz) / REL
External resistor from RSW-Osc to VDD sets the switch converter frequency. The switch converter
frequency is inversely proportional to the external R resistor value. Reducing the resistor value
by a factor of two will result in increasing the switch ScWonverter frequency by two.
2
RSW-Osc
fSW = (825kΩ • 100kHz) / RSW
3
4
VDD
EN1
Low voltage input supply pin.
Enable input signal for EL Lamp 1. CMOS logic input pin. Refer to the function table.
5
6
EN2
Enable input signal for EL Lamp 2. CMOS logic input pin. Refer to the function table.
Device ground.
GND
Drain of internal switching MOSFET. Connection for an external inductor.
The inductor LX is used to boost the low input voltage by inductive flyback. When the internal
switch is on, the inductor is being charged. When the internal switch is off, the charge stored in
the inductor will be transferred to the high voltage capacitor CS. The energy stored in the capaci-
tor is connected to the internal H-bridge, and therefore to the EL Lamp. In general, smaller value
inductors, which can handle more current, are more suitable to drive larger size Lamps. As the
inductor value decreases, the switching frequency of the inductor (controlled by RSW) should be
increased to avoid saturation.
7
LX
Connect a 100V capacitor between this pin and ground. This capacitor stores the energy trans-
ferred from the inductor.
8
CS
9
EL2
COM2
COM1
EL1
EL Lamp 2 connection.
10
11
12
Common connection for EL2 Lamp.
Common connection for EL1 Lamp.
EL Lamp 1 connection.
PWM pulse input for EL Lamp dimming. The duty cycle of the PWM signal is proportional to the
output voltage. If PWM dimming is not desired, then the PWM pin should be tied to ground.
13
14
PWM
VOUT
Switched internal reference voltage.
Input voltage to set V regulation voltage. This pin allows an external voltage source to control
the VCS amplitude. ELCLSamp dimming can be accomplished by varying the input voltage to VREG.
The VCS voltage is approximately 71 times the voltage seen on VREG.
15
16
VREG
VREF
External resistor connected between VREG and VOUT pins controls the VCS charging rate. The
charging rate is inversely proportional to the resistor value.
Internal reference voltage to set the regulation voltage. Connect an external capacitor (C ) from
VREF to ground to slowly brighten the lamp during power-up and dim down the lampREFduring
power-down. The size of the capacitor determines the time taken to brighten up or dim down. If
fade-in and fade-out are not required, this pin should be left floating. Fade in/fade out time = CREF
x 210 x 103.
6
SUPERTEX [ Supertex, Inc ]
