MAX4990E Maxim Integrated Products, MAX4990E Datasheet - Page 7

• Manufacturer Part Number: MAX4990E
• Description: High-Voltage +-15kV ESD-Protected Electroluminescent Lamp Driver
• Manufacturer: Maxim Integrated Products

The MAX4990E high-voltage DC-AC converter is ideal
for driving EL lamps. The MAX4990E features a wide
+2.4V to +5.5V input range that allows the device to
accept a wide variety of voltage sources such as sin-
gle cell Li+ batteries and higher voltage battery charg-
ers. The lamp outputs of the device generate up to
250V peak-to-peak output voltage for maximum lamp
brightness.
The MAX4990E utilizes an inductor-based boost con-
verter that allows for the use of a 220µH inductor to gen-
erate the high voltage necessary to drive an EL lamp.
The boost converter switching frequency is set with the
combination of an external capacitor connected from
the SW input to GND and an external resistor connect-
ed from SLEW to GND. Applying a PWM signal to the
SW input allows the switching frequency of the boost
converter to take the frequency of the PWM signal.
9, 11, 13
PIN
EP
10
12
14
1
2
3
4
5
6
7
8
NAME
SLEW
GND
V DD
N.C.
DIM
SW
EN
CS
V B
V A
EP
EL
LX
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Detailed Description
High-Voltage Slew-Rate Control. Connect an external resistor, R SLEW , to GND to set the slew rate of
the V A and V B high-voltage outputs.
Enable Input. Drive EN > +1.2V and DIM > +0.35V to turn on the device. Drive EN < +0.2V and DIM <
+0.15V to turn off the device.
EL Panel Dimming Control. Apply a PWM signal or DC analog control signal, or connect a resistor to
GND to adjust peak-to-peak output voltage. Use DIM together with EN to control device shutdown
(see Shutdown section).
EL Voltage Switching Frequency. Connect an external capacitor, C EL , to GND or drive with an external
oscillator to set the switching frequency of the V A and V B high-voltage outputs. Connect EL to GND to
shut off the EL oscillator. Drive EL high to keep alternatively V A or V B output high.
Boost-Converter Switching Frequency. Connect an external capacitor, C SW , to GND or drive with an
external oscillator to set the switching frequency of the boost converter. Connect SW to GND to shut
off the boost oscillator. Do not keep SW high to avoid LX shorting to GND, which causes the internal
die temperature to increase. The MAX4990E is protected by entering a themal-shutdown state. (See
the Thermal Short-Circuit Protection section.)
Power-Supply Voltage
Ground
Internal Switching DMOS Drain Connection. Connect LX to a switching inductor and an anode of a
rectifying diode.
No Connection. Leave N.C. unconnected.
High-Voltage Supply. Connect CS to output capacitor of boost converter.
High-Voltage EL Panel Output. Connect to non-V A side of EL lamp.
High-Voltage EL Panel Output. Connect to non-V B side of EL lamp.
Exposed Pad. Connect exposed pad to GND.
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
The MAX4990E uses a high-voltage full-bridge output
stage to convert the high voltage generated by the
boost converter to an AC waveform suitable for driving
the EL panel. The EL output switching frequency is set
with the combination of an external capacitor connect-
ed from EL to GND and an external resistor connected
from SLEW to GND. The MAX4990E allows programma-
bility of the EL Lamp output frequency by applying a
clock signal to the EL input. Applying a clock signal to
the EL input allows the switching frequency of the lamp
to take the frequency of the clock signal divided by 4 to
switch at the EL input frequency divided by 4.
The MAX4990E uses a proprietary acoustic noise-
reduction circuit to control the slew rate of the AC volt-
age, reducing audible noise from the EL panel. The
slew rate is set with an external resistor connected from
SLEW to GND.
The MAX4990E enters a low-power shutdown mode
(100nA max) when EN and DIM inputs are connected
FUNCTION
Pin Description
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