SP4480 Datasheet, PDF (4/13 Pages) Sipex Corporation – Dual Electroluminscent Lamp Driver

VDD
14
ROSC
3 ^OSC
1
ELEN1
SP4480
FF7
2
ELEN2
7
VSS
fCOIL
fLAMP1
fLAMP1
fLAMP2
fLAMP2
1.8kΩ
SCR1
SCR2
12 13
EL1 EL2
8
COIL
9
CAP
SCR3
SCR4
11 10
EL3 EL4
Figure 1: Internal Block Diagram of SP4480
DESCRIPTION
The SP4480 Dual Electroluminescent Lamp
Driver is a low-cost, low voltage device ideal for
the replacement of LED backlighting designs in
keypads, handsets, PDAs and other portable
designs. The EL lamp driver outputs operate in
opposite phase so the SP4480 device can be
easily implemented into applications driving
two EL lamps simultaneously or double-sided
EL lamps. Having a dual lamp driver solution
on a single IC makes available precious printed
circuit board real estate for designers additional
circuitry.
The SP4480 contains a DC-AC inverter that can
produce an AC output of 180V (typical) from
P-P
a +2.2V to +6.0V input voltage. An internal
block diagram of SP4480 can be found in Figure
1.
Electroluminescent Technology
An EL lamp consists of a thin layer of phospho-
rous material sandwiched between two strips of
plastic which emits light (flouresces) when a
high voltage AC signal is applied across it. It
high voltage AC signal is applied across it. It
behaves primarily as a capacitive load. Long
periods of DC voltage applied to the material
tend to reduce its lifetime. With these condi-
tions in mind, the ideal signal to drive an EL
lamp is a high voltage sine wave. Traditional
approaches to achieve this type of waveform
include discrete circuits incorporating a trans-
former, transistors and several resistors and
capacitors. This approach is large and bulky and
cannot be implemented in most handheld equip-
ment. Sipex offers low power single chip driver
circuits specifically designed to drive small to
medium sized electroluminescent panels. Sipex
EL drivers provide a differential AC voltage
without a DC offset to maximize EL lamp life-
time. The only additional components required
for the EL driver circuitry are an inductor, resis-
tor and capacitor.
Electroluminescent backlighting is ideal when
used with LCD's keypads or other backlit dis-
plays. EL lamps uniformly light an area without
creating any undesirable "hot spots" in the dis-
play. Also, an EL lamp consumes less power
that LED's or incandescent bulbs in similar
SP4480DS/06
SP4480 Dual Electroluminescent Lamp Driver
© Copyright 2000 Sipex Corporation
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