HV859_13 Datasheet, PDF (1/8 Pages) Supertex, Inc – High Voltage EL Lamp Driver for Low Noise Applications

Supertex inc.
HV859
High Voltage EL Lamp Driver
for Low Noise Applications
Features
►►Patented audible noise reduction
►►Patented lamp aging compensation
►►210 V_PP output voltage for higher brightness
►►Patented output timing for high efficiency
►►Single cell lithium ion compatible
►►150nA shutdown current
►►Wide input voltage range 1.8 to 5.0V
►►Separately adjustable lamp and converter
frequencies
►►Output voltage regulation
►►Split supply capability
Applications
►►LCD backlighting
►►Mobile Cellular Phone keypads
►► PDAs
►►Handheld wireless communication products
►►Global Positioning Systems (GPS)
General Description
The Supertex HV859 is a high voltage driver designed for driving
Electroluminescent (EL) lamps of up to 5.0 square inches. The
input supply voltage range is from 1.8 to 5.0V. The device uses a
single inductor and a minimum number of passive components.
The nominal regulated output voltage that is applied to the EL
lamp is ±105V. The chip can be enabled/disabled by connecting
the resistor on RSW-Osc to VDD/ground.
The HV859 has two internal oscillators, a switching MOSFET,
and a high voltage EL lamp driver. The frequency for the
switching MOSFET is set by an external resistor connected
between the RSW-Osc pin and the supply pin VDD. The EL
lamp driver frequency is set by an external resistor connected
between REL-Osc pin and the VDD pin. An external inductor is
connected between the LX and VDD pins or VIN for split supply
applications. A 0.003-0.1µF capacitor is connected between CS
and ground. The EL lamp is connected between VA and VB.
The switching MOSFET charges the external inductor and
discharges it into the capacitor at CS. The voltage at CS will
start to increase. Once the voltage at CS reaches a nominal
value of 105V, the switching MOSFET is turned OFF to conserve
power. The outputs VA and VB are configured as an H bridge
and are switching in opposite states to achieve ±105V across
the EL lamp.
Typical Application Circuit
ON = V_DD
OFF = 0V
Enable
+
V_DD
-
C_DD
R_SW
+
V_IN
-
R_EL
C_IN
1 VDD
HV859
2 RSW-Osc
VA 8
VB 7
3 REL-Osc
CS 6
4 GND
LX 5
R_SER
D
L_X
EL Lamp
C_S
Doc.# DSFP-HV859
C073013
Supertex inc.
www.supertex.com