HV862
Dimmable, Low Noise, Dual EL Lamp Driver
Features
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Adjustable output regulation for dimming
Lamp fade-in/fade-out capability
Low audible noise
180V
PP
output voltage for higher brightness
1.5V enable input logic high
Single cell lithium ion compatible
One miniature inductor to power both lamps
Separately adjustable lamp and converter frequencies
Split supply capability
16-Lead QFN package
The device uses a single inductor and a minimum number of
passive components. Using the internal reference voltage,
the regulated output voltage is at a nominal value of 90V.
The EL Lamps will therefore see ±90V. The two EL Lamps
can be turned ON and OFF using two CMOS logic inputs,
EN1 and EN2. The driver is disabled when both EN1 and
EN2 are at logic low.
The HV862 has two internal oscillators, a switching MOSFET,
and two high voltage EL Lamp driver H-bridges. Each driver
has its own half bridge common output, COM1 and COM2,
which significantly minimizes the DC offset seen by the EL
Lamp. The frequency for the switching MOSFET is set by an
external resistor connected between the R
SW-osc
pin and the
supply pin V
DD
. The EL Lamp driver frequency is set by an
external resistor connected between the R
EL-osc
pin and the
V
DD
pin. An external inductor is connected between the L
X
and V
DD
pins or V
IN
for split supply applications. Depending
upon the EL Lamp sizes, a 1.0nF to 10.0nF capacitor is
connected between the C
S
and ground.
Applications
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Dual display cellular phones
Keypad and LCD backlighting
PDAs
Handheld wireless communication products
Global Positioning Systems (GPS)
As the switching MOSFET charges the external inductor
and discharges it into the capacitor at C
S
, the voltage at
General Description
C
S
will start to increase. Once the voltage at C
S
reaches a
The Supertex HV862 is a low noise, dimmable, high nominal value of 90V, the switching MOSFET is turned OFF
voltage, dual EL Lamp driver designed for driving two to conserve power.
electroluminescent (EL) Lamps with a combined area of 5.0
square inches. The input supply voltage range is from 2.5V EL Lamp dimming can be accomplished by applying a PWM
to 4.5V. Enable input logic high can go as low as 1.5V, which logic signal to the PWM pin. The EL Lamp brightness will be
allows logic interface operating from typical 1.8V supplies. proportional to the PWM duty cycle. The HV862 can also
The device is designed to minimize audible noise emitted by slowly turn the EL Lamp ON/OFF giving a fade ON/OFF
the EL Lamps.
appearance.
Typical Application Circuit
V
IN
= 3.2V to 4.2V
4.7µF
100µH Coilcraft
LPS4012
3.3MΩ
15
14
7
8
1N4148
3.3nF
100V NPO
12
11
9
10
EL2
EL1
V
REG
V
DD
= 3.0V
0.1µF
3
2.0MΩ 1
R
EL-osc
2
R
SW-osc
825kΩ
Input Logic Control:
ON = 1.5V to V
DD
OFF = 0V to 0.2V
4
5
V
OUT
L
X
C
S
EL1
COM1
EL2
V
DD
EN1
EN2
V
REF
16
COM2
PWM
13
GND
6
2.2µF
HV862K7-G
SUPERTEX [ Supertex, Inc ]
