MAX4990E Maxim Integrated Products, MAX4990E Datasheet - Page 8

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

to GND. The MAX4990E also enters thermal shutdown
if the die temperature rises above +158°C.
The MAX4990E features an EL lamp dimming control
(DIM) that allows the user to set the EL output voltage
with a PWM, DC analog voltage, or a resistor connect-
ed to GND. A capacitor placed in parallel to the resistor
on the DIM input allows the user to program a slow
turn-on/-off time of the MAX4990E’s outputs to generate
a soft fade-on/fade-off effect of the EL lamp.
The high-voltage outputs are ESD protected up to
±15kV Human Body Model, ±15kV Air-Gap Discharge,
and ±4kV Contact Discharge, as specified in the IEC
61000-4-2 specification.
The slew rate, frequency, and peak-to-peak voltage of the
MAX4990E EL lamp outputs are programmed through a
combination of external components and/or DC inputs.
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
8
_______________________________________________________________________________________
SLEW
GND
DIM
V
SW
EN
DD
EL
OSCILLATOR
LOW-POWER
CONVERTER
SHUTDOWN
CONVERTER
SHUTDOWN
SWITCH
OSCILLATOR
THERMAL
UVLO
PWM
V-I
EL
EL Output Voltage
TIMEOUT
LOW PEAK
DETECTOR
TIMEOUT
LOW-POWER
REF
SHUTDOWN
+
-
DRIVER
DMOS
+
-
SHUTDOWN
The device uses resistor R
used as a reference current for the MAX4990E internal
circuitry. The reference current directly affects the slew
rate of the EL lamp output. Increasing the value of
R
value of R
Resistor Selection section on how to select R
The MAX4990E EL lamp output frequency uses an
internal EL oscillator to set the desired frequency. The
output frequency is adjusted by either 1) the combina-
tion of a resistor from SLEW to GND and an external
capacitor from the EL input to GND, or 2) by driving a
clock signal directly into the EL input. (See the C
Capacitor Selection section for choosing the C
capacitor value.)
The peak-to-peak voltage of the EL lamp output is var-
ied from 70V
voltage ranging from +0.35V to +1.3V to the DIM input.
SLEW
V
NO-OPERATION
SENSE
SIGNAL
decreases the slew rate, and decreasing the
SLEW
P-P
H-BRIDGE
increases the slew rate. (See the R
to 250V
MAX4990E
P-P
Functional Diagram
N
PROTECTION
PROTECTION
SLEW
HIGH ESD
HIGH ESD
by applying an external DC
to set the bias current
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LX
CS
V
V
A
B
SLEW
.)
SLEW
EL
EL