HV853
High Voltage, Low Noise,
Inductorless EL Lamp Driver
Features
►
No external components required when using an
external EL clock frequency
►
Audible noise reduction with improved EMI
►
EL frequency can be set by an external resistor
►
DC to AC converter
►
Drives up to 5.3nF (approx. 1.5in
2
lamp) load
►
Output voltage regulation
►
Enable function
►
Available in 8-Lead DFN and MSOP packages
General Description
The Supertex HV853 is a high voltage, low noise EL
(electroluminescent) lamp driver. It is the low noise version of
the HV852 with improved EMI performance, operating over an
input voltage range of 3.2V to 5.0V. It is designed to drive EL
lamps of up to 1.5in
2
, with capacitive values up to 5.3nF. The
HV853 converts a low voltage DC input to a high voltage AC
output across an EL lamp. A nominal regulated output voltage
of ±80V is applied to the 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.
The EL lamp frequency can be set either by an external
resistor R
EL
or by applying an external clock where the clock
frequency is divided by 128 to set the EL lamp frequency.
Applications
►
►
►
►
Cellular phone keypad
Watches
Small handheld wireless devices
MP3 Players
Typical Application Circuits
V
DD
= ON
GND = OFF
1
+
V
DD
= ON
GND = OFF
R
EL
2
3
4
V
DD
R
EL
EN
CLK
IN
V
A
V
B
GND
CLK
EN
8
7
6
5
V
DD
GND
1
V
DD
-
C
DD
EL
LAMP
+
V
DD
R
EL
EN
CLK
IN
V
A
V
B
GND
CLK
EN
8
7
6
5
V
DD
V
DD
-
C
DD
2
3
4
EL
LAMP
HV853
EL Lamp Frequency set by R
EL
HV853
EL Lamp Frequency set by External Clock
SUPERTEX [ Supertex, Inc ]
