HV852
High Voltage, Low Noise,
Inductorless EL Lamp Driver
Features
►
No external components required when using an
external EL clock frequency
►
EL frequency can be set by an external resistor
►
Low Noise
►
DC to AC converter
►
Drives up to 5.3nF (approx. 1.5in
2
lamp) load
►
Output voltage regulation
►
Enable function
General Description
The Supertex HV852 is a high voltage, low noise, inductorless
EL (electroluminescent) lamp driver. It is designed to drive EL
lamps of up to 1.5in
2
, with capacitive values up to 5.3nF over
an input voltage range of 2.4V to 5.0V. The HV852 converts
a low voltage DC input to a high voltage AC output across an
EL lamp. It uses a charge pump scheme to boost the input
voltage eliminating the need for an external inductor, diode,
and high voltage capacitor commonly found in conventional
topologies.
The charge pump circuit discharges its energy into an EL lamp
through a high voltage H-bridge. Once the voltage reaches
its regulated limit, it is turned off to conserve power. The EL
lamp is then discharged to ground and the H-bridge changes
state to allow the charge pump to charge the EL lamp in the
opposite direction.
Applications
►
►
►
►
Cellular phone keypad
Watches
Small handheld wireless devices
MP3 Players
Typical Application Circuit
+
V
DD
-
C
DD
R
EL
V
DD
R
EL
EN
CLK
IN
V
A
V
B
GND
CLK
EN
EL
LAMP
V
DD
= ON
GND = OFF
HV852
EL Lamp frequency set by R
EL
SUPERTEX [ Supertex, Inc ]
