HV860 Datasheet, PDF (1/7 Pages) Supertex, Inc – Low Noise Dimmable EL Lamp Driver

Supertex inc.
HV860
Initial Release
Low Noise Dimmable EL Lamp Driver
Features
► Adjustable output regulation for dimming
► 220V_PP output voltage for higher brightness
► Single cell lithium ion compatible
► 150nA shutdown current
► Separately adjustable lamp and converter frequencies
► 3x3 QFN-12 package
► Split supply capability
Applications
► Mobile cellular phone keypads
► PDAs
► Handheld wireless communication products
► Global Positioning Systems (GPS)
General Description
The Supertex HV860 is a high voltage driver designed for
driving Electroluminescent, (EL), lamps of up to 5 square
inches. The input supply voltage range is from 2.5V to 4.5V.
The device uses a single inductor and a minimum number of
passive components. Using the internal reference voltage,
the regulated output voltage is at a nominal voltage of 110V.
The EL lamp will therefore see ±110V. An enable pin, (EN),
is available to turn the device on and off via a logic signal.
The HV860 has two internal oscillators, a switching
MOSFET, and a high voltage EL lamp driver H-bridge. The
frequency for the switching MOSFET is set by an external
resistor connected between the R_SW-OSC pin and the supply
pin V_DD. The EL lamp driver frequency is set by an external
resistor connected between R
pin and V pin. An
EL-OSC
DD
external inductor is connected between the L_X and V_DD
pins or V_IN for split supply applications. A 3.0nF capacitor
is connected between C_S and ground. The EL lamp is
connected between V_A and V_B.
The switching MOSFET charges the external inductor and
discharges it into the capacitor at C_S. The voltage at C_S will
start to increase. Once the voltage at C_S reaches a nominal
value of 110V, the switching MOSFET is turned OFF to
conserve power. The outputs V_A and V_B are configured as
an H bridge and are switching in opposite states to achieve
±110V across the EL lamp.
EL lamp dimming can be accomplished by changing the
input voltage to the V_REG pin. The V_REG pin allows an external
voltage source to control the V_CS amplitude. The V_CS voltage
is approximately 87 times the voltage seen on V_REG.
Typical Application Circuit
V_IN
V_DD
C_DD
1.5V = On
0V = Off
C_IN
L_X
R_REG
D
2
35
R_SW
10
12
V_REG
V_DD
R_SW-OSC
V_REF
1 _REL-OSC
L_X
C_S
V_A
7
9
R_{EL 11 EN}
GND
V_B ⁸
4
C_S
EL
Lamp
HV860K7
NR040306
· · · · ^{Supertex inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: [phone] FAX: [phone] www.supertex.com}
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