HV860_09 Datasheet, PDF (1/8 Pages) Supertex, Inc – Low Noise, Dimmable EL Lamp Driver

HV860
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
► 3x3mm 12-Lead QFN 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 2.5 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 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
VDD pin. An external inductor is connected between the LX
and VDD pins or VIN for split supply applications. A 3.0nF
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 110V, 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
±110V across the EL lamp.
EL lamp dimming can be accomplished by changing the
input voltage to the VREG pin. The VREG pin allows an
external voltage source to control the VCS amplitude. The
VCS voltage is approximately 87 times the voltage seen on
VREG.
Typical Application Circuit
V_IN
C_IN
L_X
R_REG
D
V_DD
C_DD
1.5V = On
0V = Off
R_SW
R_EL
2
35
VREG VREF LX
10 _VDD
CS ⁷
12 _RSW-Osc
1 _REL-Osc
9
VA
11 _EN
GND
VB ⁸
4 _HV860
C_S
EL
Lamp
● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: [phone] ● www.supertex.com