MAX4990E Ver la hoja de datos (PDF) - Maxim Integrated
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MAX4990E Datasheet PDF : 15 Pages
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High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
Functional Diagram
VDD
SW
SWITCH
OSCILLATOR
TIMEOUT
+-
EL
EL
OSCILLATOR
REF
LX
N
CS
SLEW
EN
DIM
GND
V-I
CONVERTER
LOW-POWER
SHUTDOWN
PWM
CONVERTER
LOW PEAK
DETECTOR
-+
VSENSE
DMOS
DRIVER
H-BRIDGE
HIGH ESD
PROTECTION
VA
HIGH ESD
PROTECTION
VB
THERMAL
SHUTDOWN
UVLO
TIMEOUT LOW-POWER
SHUTDOWN
SHUTDOWN
NO-OPERATION
SIGNAL
MAX4990E
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.
EL Output Voltage
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.
The device uses resistor RSLEW to set the bias current
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
RSLEW decreases the slew rate, and decreasing the
value of RSLEW increases the slew rate. (See the RSLEW
Resistor Selection section on how to select RSLEW.)
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 CEL
Capacitor Selection section for choosing the CEL
capacitor value.)
The peak-to-peak voltage of the EL lamp output is var-
ied from 70VP-P to 250VP-P by applying an external DC
voltage ranging from +0.35V to +1.3V to the DIM input.
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