HV881 Datasheet, PDF (1/8 Pages) Supertex, Inc – Dimmable, Low Noise, 16 channel EL Lamp Driver

Supertex inc.
Dimmable, Low Noise, 16 channel
EL Lamp Driver
HV881
Features
►► Sixteen channel EL lamp driver with single common
terminal
►► 1nF maximum load on each of the sixteen channels
►► Independent dimming capability for all lamps
►► Sixteen brightness levels for each lamp
►► 1.8 to 5.5V operating supply range
►► 1.7V logic interface
►► Dedicated enable logic pin
►► 340V_P-P nominal output voltage for high brightness
►► Low audible noise
►► Output voltage regulation
►► EL1 - EL16 outputs fall time control
►► Two EL frequency controls
►► External switching MOSFET
►► I²C data communication control
►► Single lithium-ion cell compatible
►► One miniature inductor to power sixteen lamps
►► Independent lamp and converter frequency setting
►► Split supply capability
►► 5x5mm, 32-Lead QFN package
The HV881 has two internal oscillators and a high voltage
EL lamp driver. An external MOSFET is driven by the switch
oscillator to generate output voltage.
The frequency for the external switching MOSFET is set
by an external resistor connected between the RSW-Osc
pin and the VDD supply pin. The EL lamp driver frequency
can be set by either an external logic signal frequency at
the SEL pin or by an external resistor connected between
the REL-Osc pin and VDD pin. If external frequency is input
at the SEL pin, the REL-Osc pin should be connected to
ground.
An external inductor is connected between the LX and VDD
or VIN pins for split supply applications. Depending upon
the EL lamp sizes, a 1.0 to 10.0nF capacitor is connected
between the CS pin and ground. The C_S capacitor is
connected to the internal H-bridge, and the energy stored
in the capacitor is therefore transferred to the EL lamp.
One side of all the sixteen EL lamps is connected to the
respective EL pins (EL1, EL2, etc.), and the other side is
connected to the COM pin.
Applications
►► Multi-segment, variable displays
►► Cell phone keypads and displays
►► Multi-segment remote controls
►► Handheld wireless communication products
►► Global Positioning Systems (GPS)
General Description
The Supertex HV881 is a 16 channel EL lamp driver with a
single common terminal. It can drive up to a 1nF EL lamp load
(approx. 0.3in2 lamp size) on each of the sixteen channels.
The input supply voltage range is 1.8 to 5.5V. The logic
interface to the device can be as low as 1.7V. The device
has an enable logic input pin to turn the device on or off.
The device is designed to minimize audible noise emitted by
the EL lamp. The HV881 uses an external MOSFET, a single
inductor and minimum number of passive components to
drive all sixteen EL lamps. The device is designed such that
the input voltage to the inductor can be different from the
input voltage to the device (split supply).
The external switching MOSFET charges the inductor and
discharges it into the capacitor at CS. The voltage at CS
will start to increase. Once the voltage at CS reaches the
desired regulation limit, the external switching MOSFET is
turned off to conserve power.
The HV881 allows for controlling the fall time of the EL1
- EL16 outputs by an external resistor from the RSLOPE
pin to the VDD pin. This feature can be used to reduce
the audible noise of the EL lamp or to increase the lamp
brightness.
The brightness of each of the sixteen EL lamps can be
independently controlled to have one of fifteen brightness
levels or can be completely turned off by the serial data
(SDA) input. The serial data input has a 4-bit binary code
for each lamp, to control the brightness level from level 0
to level 15. The brightness is controlled by controlling the
number of EL frequency cycles (from 0 to 15) in a group of
15 cycles.
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: [phone] ● www.supertex.com