Supertex inc.
HV859
Initial Release
High Voltage EL Lamp Driver for Low Noise Applications
Features
General Description
ꢀ Patented audible noise reduction
ꢀ Patented lamp aging compensation
ꢀ 210 VPP output voltage for higher brightness
ꢀ Patented output timing for high efficiency
ꢀ Single cell lithium ion compatible
ꢀ 150nA shutdown current
ꢀ Wide input voltage range 1.8V to 5.0V
ꢀ Separately adjustable lamp and converter
frequencies
ꢀ Output voltage regulation
ꢀ Split supply capability
The Supertex HV859 is a high voltage driver designed for
driving Electroluminescent (EL) lamps of up to 5 square
inches. The input supply voltage range is from 1.8V 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 R
pin and the supply pin VDD. The EL lamp
driver frequenScWy-OiSsC set by an external resistor connected
Applications
ꢀ LCD backlighting
ꢀ Mobile Cellular Phone keypads
ꢀ PDAs
ꢀ Handheld wireless communication products
ꢀ Global Positioning Systems (GPS)
between R
pin and the VDD pin. An external inductor is
connected EbLe-OtSwCeen the L and VDD pins or VIN for split supply
applications. A 0.003-0.1XµF capacitor is connected between
C and ground. The EL lamp is connected between VA and
VBS.
The switching MOSFET charges the external inductor and
discharges it into the capacitor at CS. The voltage at C will start
to increase. Once the voltage at CS reaches a nomiSnal value
of 105V, the switching MOSFET is turned OFF to conserve
power. The outputs VA and V are configured as an H bridge
and are switching in oppositeBstates to achieve 105V across
the EL lamp.
Typical Application Circuit
Enable
ON = VDD
OFF = 0V
RSER
1
2
3
4
VDD
8
7
6
5
VA
VB
RSW
+
-
RSW-osc
REL-osc
GND
CDD
EL Lamp
VDD
CS
LX
D
REL
HV859MG/
HV859K7
LX
+
-
CIN
CS
VIN
NR040306
Supertex inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: (408) 222-8888 FAX: (408) 222-4895 www.supertex.com
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