HV850 Datasheet, PDF (1/6 Pages) Supertex, Inc – High Voltage Low Noise Inductorless EL Lamp Driver

HV850
________________________________________________________________________________
Initial Release
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 4.5nF load (approx. 2.0² inches)
Output voltage regulation
Enable function
Applications
Cell phone keypads and displays
Transceivers
MP3 Players
Watches
Pagers
Measuring instruments/gauges
General Description
Supertex HV850 is a high voltage electroluminescent
(EL) Lamp Driver IC. It is designed to drive EL lamps
of up to 2.0in², with capacitive values up to 4.5nF.
HV850 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.
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.
Typical Application Circuits
V_DD=ON
GND=OFF
+
V_DD
-
V_DD
GND
C_DD
V_DD
V_A
R_EL
V_B
EN
GND
Clk-in Clk-en
HV850MG
EL
Lamp
V_DD
EL lamp frequency set by an external clock
V_DD=ON
GND=OFF
+
V_DD
-
C_DD
R_EL
V_DD
R_EL
EN
V_A
V_B
GND
Clk-in Clk-en
HV850MG
EL lamp frequency set by R_EL
EL
Lamp
Supertex, Inc.
1
1/21/04