General Description
The MAX4990 high-voltage DC-AC converter is ideal for
driving electroluminescent (EL) lamps. The MAX4990
features a wide +2.4V to +5.5V input range that allows
the device to accept a wide variety of voltage sources
such as single-cell lithium-ion (Li+) batteries and higher
voltage battery chargers. The lamp outputs of the
device generate up to 250V peak-to-peak output volt-
age for maximum lamp brightness.
The MAX4990 utilizes an inductor-based boost convert-
er to generate the high voltage necessary to drive an
EL lamp. The boost-converter switching frequency is
set with the combination of an external capacitor con-
nected from SW to GND and an external resistor con-
nected from SLEW to GND.
The MAX4990 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 MAX4990 uses a proprietary acoustic noise-reduction
circuit that controls the slew rate of the AC voltage, reduc-
ing audible noise from the EL panel. The slew rate is set
with an external resistor connected from SLEW to GND.
The MAX4990 features an EL lamp dimming control
(DIM) that allows the user to set the EL output voltage
with a PWM signal, a DC analog voltage, or a resistor
connected from the DIM input to GND. A capacitor
placed in parallel to the resistor on DIM allows the user
to program a slow turn-on/-off time that generates a soft
fade-on/fade-off effect of the EL lamp.
The MAX4990 enters a low-power shutdown mode
(100nA max) when the EN and DIM inputs are connected
to GND. The MAX4990 also enters thermal shutdown
if the die temperature rises above +158°C.
The MAX4990 is available in a space-saving, 14-pin,
3mm x 3mm TDFN package and is specified over the
extended -40°C to +85°C operating temperature range.
Features
oESD-Protected EL Lamp Outputs
±15kV Human Body Model
±4kV IEC 61000-4-2 Contact Discharge
±15kV IEC 61000-4-2 Air-Gap Discharge
o250VP-P (MAX) Output for Highest Brightness
oWide +2.4V to +5.5V Input Voltage Range
oResistor-Adjustable Slew-Rate Control for
Audible Noise Reduction
oExternally Driven Lamp and Switching Converter
Frequencies
oCapacitor-Adjustable Lamp and Switching
Converter Frequencies
oLow 100nA Shutdown Current
oDIM Input for Controlling Output Voltage Through
DC Analog Voltage, PWM, or Resistor to GND
oCapacitor Adjustable for Slow Turn-On/-Off
oSpace-Saving Packages
14-Pin, 3mm x 3mm TDFN
Applications
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
________________________________________________________________
Maxim Integrated Products
1
19-0886; Rev 1; 11/07
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Ordering Information
Note: The device operates over the -40°C to +85°C operating
temperature range.
+
Denotes a lead-free package.
EP = Exposed paddle.
PART PIN-PACKAGE TOP
MARK
PKG
CODE
±15kV
PROTECTION DIM CONTROL SLEW-RATE
CONTROL
MAX4990ETD+ 14 TDFN-EP (3mm x 3mm) ADL T1433-2 Yes Yes Yes
Keypad Backlighting
MP3 Players
LCD Backlighting
PDAs/Smartphones
Automotive Instrument
Clusters
MAX4990
TDFN-EP
TOP VIEW
245
13 11 10
N.C.
N.C.
CS
EN
EL
SW
1
+
14
VA
SLEW
3
12
VB
DIM
6
9
N.C.VDD
7
8
LXGND
*EP = EXPOSED PAD. CONNECT EP TO GND OR LEAVE UNCONNECTED.
*EP
Pin Configuration
Typical Application Circuits appear at end of data sheet.
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD = +2.4V to +5.5V, CLAMP = 10nF, CCS = 3.3nF, LX= 220µH (ISAT = 170mA, RS= 5.5Ω), TA= TMIN to TMAX, unless otherwise
noted. Typical values are at VDD = +3.0V and TA = +25°C.) (Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
(All voltages referenced to GND.)
VDD ...........................................................................-0.3V to +7V
CS, LX...................................................................-0.3V to +160V
VA, VB.........................................................-0.3V to (VCS + 0.3V)
EN, EL, SLEW, DIM, SW.............................-0.3V to (VDD + 0.3V)
Continuous Power Dissipation (TA= +70°C)
14-Pin TDFN (derate 24.4mW/°C above +70°C) ...... 1951mW
JA.................................................................................41°C/W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Power-Supply Voltage VDD 2.4 5.5 V
Power-Supply Current IDD RSLEW = 375kΩ, slope = 30V/100µs;
fEL = 200Hz, VA - VB = 250VP-P 350 µA
EN = 0V, DIM = 0V, TA = +25°C 25 100
Shutdown Supply Current ISHDN EN = 0V, DIM = 0V, TA = -40°C to +85°C 300 nA
Shutdown Inductor Supply
Current ILXSHDN EN = 0V, DIM = 0V, LX = VDD, CS = VDD 1500 nA
Undervoltage Lockout VLO VDD rising 1.8 2.1 2.3 V
UVLO Hysteresis VHYST 125 mV
EL OUTPUTS (VA - VB)
VDD = +3V, DIM = +0.5V 84 100 122
VDD = +3V, DIM = +1V 170 200 230Peak-to-Peak Output Voltage VA - VB
VDD = +3V, DIM = +1.3V 210 250 280
V
Pulldown Switch On-Resistance RONPD ISINK = 1mA, VCS = +10V,
VA, VB < +0.6V, VDD = +3V 50 165 500 Ω
Pullup Switch On-Resistance RONPU VCS = +125V, ISOURCE = 1mA 700 1500 2200 Ω
ILKG_NMOS VA = +125V, VB = +125V, shutdown mode,
VCS = +125V -1 +1
Switch Off-Leakage
ILKG_PMOS VA = 0V, VB = unconnected, shutdown
mode, VCS = +125V -60 +60
µA
VA, VB Differential Resistor VAB_RES VA = +0.1V, VB = 0V, shutdown mode,
CS = unconnected 27MΩ
EL Lamp Switching Frequency fEL CEL = 872pF, RSLEW = 375kΩ210 250 290 Hz
Human Body Model ±15
IEC 61000-4-2 Contact Discharge ±4ESD Protection (VA, VB Only)
IEC 61000-4-2 Air-Gap Discharge ±15
kV
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.4V to +5.5V, CLAMP = 10nF, CCS = 3.3nF, LX= 220µH (ISAT = 170mA, RS= 5.5Ω), TA= TMIN to TMAX, unless otherwise
noted. Typical values are at VDD = +3.0V and TA = +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
BOOST CONVERTER
VDD = +3V, DIM = +0.5V forced externally 42 50 61
VDD = +3V, DIM = +1V forced externally 85 100 115Output Peak Voltage VCS
VDD = +3V, DIM = +1.3V forced externally 105 125 140
V
Boost Switching Frequency fSW CSW = 96pF, RSLEW = 375kΩ80 100 120 kHz
Switch On-Resistance RLX ISINK = 25mA, VDD = +3V 20 Ω
LX Leakage Current ILX VLX = +125V -1 +1 µA
CS Input Current ICS No load, VCS = +125V, EN = 0V, DIM = 0V 50 µA
CONTROL INPUT SW
Input Voltage-High Threshold VIH_SW RSLEW = 375kΩ0.9 0.98 1.06 V
Input Voltage-Low Threshold VIL_SW RSLEW = 375kΩ0.43 0.49 0.55 V
Input Low Current IIL_SW RSLEW = 375kΩ, CS = +40V, EL = VDD,
DIM = VDD 43 77 µA
Input High Current IIH_SW RSLEW = 375kΩ, CS = +40V, EL = VDD,
DIM = VDD 5.0 7.5 µA
CONTROL INPUT EL
Input Voltage-High Threshold VIH_CEL RSLEW = 375kΩ1.08 1.32 V
Input Voltage-Low Threshold VIL_CEL RSLEW = 375kΩ0.22 0.39 V
Input Low Current IIL_CEL RSLEW = 375kΩ1.2 1.87 µA
Input High Current IIH_CEL RSLEW = 375kΩ1.2 1.87 µA
CONTROL INPUT SLEW
Force Voltage VFORCE ISOURCE = 20µA 0.89 0.95 1.04 V
High-Voltage Output Slew Rate RSLEW = 375kΩ30 V/100µs
CONTROL INPUT DIM
Input Logic-High Voltage VIH_DIM Output voltage (max) 1.3 V
Input Logic-Low Voltage VIL_DIM Output voltage (off) 0.15 V
Input Low Current IIL_DIM VDIM = 0V, RSLEW = 375kΩ2.22 3.0 µA
Input High Current IIH_DIM VDIM = VDD -1 +1 µA
PWM Frequency Range 0.2 to 1 MHz
Low-Peak Detector Threshold VLPD 0.15 0.35 V
Low-Peak Detector Hysteresis VLPD_HYST 100 mV
CONTROL INPUT EN
Input Voltage-High Threshold VIH_EN 1.2 V
Input Voltage-Low Threshold VIL_EN 0.2 V
Input Low Current IIL_EN -1 +1 µA
Input High Current IIH_EN -1 +1 µA
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
4 _______________________________________________________________________________________
0
6
4
2
8
10
12
14
16
18
20
2.4 3.63.0 4.2 4.8 5.4
TOTAL INPUT CURRENT
vs. SUPPLY VOLTAGE
MAX4990 toc01
SUPPLY VOLTAGE (V)
TOTAL INPUT CURRENT (mA)
0
4
12
8
16
20
-40 10-15 35 60 85
TOTAL INPUT CURRENT
vs. TEMPERATURE
MAX4990 toc02
TEMPERATURE (°C)
TOTAL INPUT CURRENT (mA)
80
60
40
20
0
40 12080 160 200
TOTAL INPUT CURRENT AND
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. BOOST CONVERTER FREQUENCY
MAX4990 toc03
BOOST CONVERTER FREQUENCY (kHz)
TOTAL INPUT CURRENT (mA)
300
225
150
75
0
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
- - - - PEAK-TO-PEAK OUTPUT VOLTAGE
90% DUTY CYCLE
CCS = 4.7nF
CCS = 2.2nF
CCS = 2.2nF
CCS = 4.7nF
0
0.2
0.6
0.4
0.8
1.0
2.4 3.63.0 4.2 4.8 5.4
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
MAX4990 toc04
SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT (nA)
DIM = EN = 0V
-40 10-15 35 60 85
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX4990 toc05
TEMPERATURE (°C)
SHUTDOWN CURRENT (nA)
10
1
0.1
0.01
100 DIM = EN = 0V
0
100
50
200
150
250
300
2.4 5.4
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX4990 toc06
SUPPLY VOLTAGE (V)
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
3.63.0 4.2 4.8
DIM = 1.3V
DIM = 1.0V
DIM = 0.8V
DIM = 0.6V
Typical Operating Characteristics
(VDD = +3.6V, CLAMP = 10nF, CCS = 3.3nF, LX= 220µH (ISAT = 170mA, RS= 5.5Ω), RSLEW = 390kΩ, DIM = VDD, CSW = 100pF,
CEL = 1.2nF, TA= +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.4V to +5.5V, CLAMP = 10nF, CCS = 3.3nF, LX= 220µH (ISAT = 170mA, RS= 5.5Ω), TA= TMIN to TMAX, unless otherwise
noted. Typical values are at VDD = +3.0V and TA = +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
THERMAL SHUTDOWN
Thermal Shutdown 158 °C
Thermal Shutdown Hysteresis 8°C
Note 1: Specifications at TA= -40°C are guaranteed by design and not production.
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
_______________________________________________________________________________________ 5
180
190
185
200
195
205
210
-40 85
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. TEMPERATURE
MAX4990 toc07
TEMPERATURE (°C)
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
10-15 35 60
0
100
50
200
150
250
300
0.35 1.30
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. DIM VOLTAGE
MAX4990 toc08
DIM VOLTAGE (V)
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
0.730.54 0.92 1.11
VDD = 4.5V
0
100
50
200
150
250
300
20 40 60 80
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. DIM DUTY CYCLE
MAX4990 toc09
DIM DUTY CYCLE (%)
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
fDIM = 200kHz
fDIM = 1MHz
0
40
20
80
60
100
120
2.4 5.4
RMS OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX4990 toc10
SUPPLY VOLTAGE (V)
RMS OUTPUT VOLTAGE (V)
3.63.0 4.2 4.8
-1000
-700
-800
-900
-600
-500
-400
-300
-200
-100
0
2.4 3.63.0 4.2 4.8 5.4
AVERAGE OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX4990 toc11
SUPPLY VOLTAGE (V)
AVERAGE OUTPUT VOLTAGE (mV)
-1000
-700
-800
-900
-600
-500
-400
-300
-200
-100
0
-40 10-15 356085
AVERAGE OUTPUT VOLTAGE
vs. TEMPERATURE
MAX4990 toc12
TEMPERATURE (°C)
AVERAGE OUTPUT VOLTAGE (mV)
0
100
300
200
400
500
EL SWITCHING FREQUENCY vs.CEL
MAX4990 toc13
CEL (nF)
EL SWITCHING FREQUENCY (Hz)
0.5 1.51.0 2.0 2.5
RSLEW = 390kΩ190
185
180
175
170
2.4 3.63.0 4.2 4.8 5.4
EL SWITCHING FREQUENCY
vs. SUPPLY VOLTAGE
MAX4990 toc14
SUPPLY VOLTAGE (V)
EL SWITCHING FREQUENCY (Hz)
190
185
180
175
170
-40 10-15 35 60 85
EL SWITCHING FREQUENCY
vs. TEMPERATURE
MAX4990 toc15
TEMPERATURE (°C)
EL SWITCHING FREQUENCY (Hz)
Typical Operating Characteristics (continued)
(VDD = +3.6V, CLAMP = 10nF, CCS = 3.3nF, LX= 220µH (ISAT = 170mA, RS= 5.5Ω), RSLEW = 390kΩ, DIM = VDD, CSW = 100pF,
CEL = 1.2nF, TA= +25°C, unless otherwise noted.)
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
6 _______________________________________________________________________________________
160
120
80
40
0
80 150115 185 220
BOOST CONVERTER FREQUENCY vs. CSW
MAX4990 toc16
CSW (pF)
BOOST CONVERTER FREQUENCY (kHz)
RSLEW = 390kΩ110
105
100
95
90
2.4 3.63.0 4.2 4.8 5.4
BOOST CONVERTER FREQUENCY
vs. SUPPLY VOLTAGE
MAX4990 toc17
SUPPLY VOLTAGE (V)
BOOST CONVERTER FREQUENCY (kHz)
110
105
100
95
90
-40 -10-15 356085
BOOST CONVERTER FREQUENCY
vs. TEMPERATURE
MAX4990 toc18
TEMPERATURE (°C)
BOOST CONVERTER FREQUENCY (kHz)
OUTPUT VOLTAGE SLOPE vs. RSLEW
MAX4990 toc19
0
5
15
10
30
35
25
20
40
OUTPUT VOLTAGE SLOPE (V/100μs)
300 500 600400 700 800 900 1000
RSLEW (kΩ)
22
24
28
26
30
32
2.4 3.63.0 4.2 4.8 5.4
OUTPUT VOLTAGE SLOPE
vs. SUPPLY VOLTAGE
MAX4990 toc20
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE SLOPE (V/100μs)
22
24
28
26
30
32
-40 10-15 35 80 85
OUTPUT VOLTAGE SLOPE
vs. TEMPERATURE
MAX4990 toc21
TEMPERATURE (°C)
OUTPUT VOLTAGE SLOPE (V/100μs)
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
01.20.6 1.8 2.4 3.0 3.6
SLOW TURN-ON/-OFF TIME vs. CDIM
MAX4990 toc22
CDIM (μF)
SLOW TURN ON/OFF TIME (s)
RDIM = 390kΩ
tON
tOFF
25
0
20
15
10
5
2.4 3.63.0 4.2 4.8 5.4
BRIGHTNESS AND TOTAL INPUT CURRENT
vs. SUPPLY VOLTAGE
MAX4990 toc23
SUPPLY VOLTAGE (V)
BRIGHTNESS (cd/m2)
30
22
18
14
26
10
TOTAL INPUT CURRENT (mA)
- - - - SUPPLY CURRENT
CLAMP = 20nF
TYPICAL VA, VB, AND
VA - VB WAVEFORMS
MAX4990 toc24
1ms/div
VA - VB
100V/div
VA
50V/div
VB
50V/div
Typical Operating Characteristics (continued)
(VDD = +3.6V, CLAMP = 10nF, CCS = 3.3nF, LX= 220µH (ISAT = 170mA, RS= 5.5Ω), RSLEW = 390kΩ, DIM = VDD, CSW = 100pF,
CEL = 1.2nF, TA= +25°C, unless otherwise noted.)
Detailed Description
The MAX4990 high-voltage DC-AC converter is ideal
for driving EL lamps. The MAX4990 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 MAX4990 utilizes an inductor-based boost convert-
er that allows for the use of a 220µH inductor to gener-
ate 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 connected
from SLEW to GND. Applying a PWM signal to the SW
input allows the switching frequency of the boost con-
verter to take the frequency of the PWM signal.
The MAX4990 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 MAX4990 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 MAX4990 uses a proprietary acoustic noise-reduc-
tion circuit to control the slew rate of the AC voltage,
reducing audible noise from the EL panel. The slew rate
is set with an external resistor connected from SLEW to
GND.
The MAX4990 enters a low-power shutdown mode
(100nA max) when EN and DIM inputs are connected
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
_______________________________________________________________________________________ 7
Pin Description
PIN NAME FUNCTION
1 SLEW High-Voltage Slew-Rate Control. Connect an external resistor, RSLEW, to GND to set the slew rate of
the VA and VB high-voltage outputs.
2EN
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.
3 DIM
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).
4EL
EL Voltage Switching Frequency. Connect an external capacitor, CEL, to GND or drive with an external
oscillator to set the switching frequency of the VA and VB high-voltage outputs. Connect EL to GND to
shut off the EL oscillator. Drive EL high to keep alternatively VA or VB output high.
5SW
Boost-Converter Switching Frequency. Connect an external capacitor, CSW, 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 MAX4990 is protected by entering a themal-shutdown state. (See the
Thermal Short-Circuit Protection section.)
6V
DD Power-Supply Voltage
7 GND Ground
8LX
Internal Switching DMOS Drain Connection. Connect LX to a switching inductor and an anode of a
rectifying diode.
9, 11, 13 N.C. No Connection. Leave N.C. unconnected.
10 CS High-Voltage Supply. Connect CS to output capacitor of boost converter.
12 VBHigh-Voltage EL Panel Output. Connect to non-VA side of EL lamp.
14 VAHigh-Voltage EL Panel Output. Connect to non-VB side of EL lamp.
EP EP Exposed Pad. Connect exposed pad to GND.
MAX4990
to GND. The MAX4990 also enters thermal shutdown if
the die temperature rises above +158°C.
The MAX4990 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 MAX4990’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
MAX4990 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 MAX4990 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
R
SLEW
Resistor Selection
section on how to select RSLEW.)
The MAX4990 EL lamp output frequency uses an inter-
nal EL oscillator to set the desired frequency. The out-
put frequency is adjusted by either 1) the combination
of a resistor from SLEW to GND and an external capaci-
tor from the EL input to GND, or 2) by driving a clock
signal directly into the EL input. (See the
C
EL
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.
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
8 _______________________________________________________________________________________
+-
-+
SWITCH
OSCILLATOR
VDD
SW
LX
CS
VA
VB
EL
SLEW
EN
DIM
GND
TIMEOUT
EL
OSCILLATOR
V-I
CONVERTER
HIGH ESD
PROTECTION
H-BRIDGE
HIGH ESD
PROTECTION
DMOS
DRIVER
REF
N
VSENSE
LOW-POWER
SHUTDOWN
LOW PEAK
DETECTOR
LOW-POWER
SHUTDOWN
SHUTDOWN
NO-OPERATION
SIGNAL
TIMEOUT
PWM
CONVERTER
THERMAL
SHUTDOWN
UVLO
MAX4990
Functional Diagram
Increasing the voltage on the DIM input increases the
peak-to-peak voltage, and decreasing the voltage on
the input decreases the peak-to-peak voltage. The EL
lamp peak-to-peak voltage is also adjusted by applying
a PWM signal to the DIM input. The duty cycle of the
PWM determines the EL lamp output peak-to-peak volt-
age. As the duty cycle is increased, the peak-to-peak
output voltage is increased, and as the duty cycle is
decreased, the peak-to-peak voltage is decreased. The
MAX4990 also features a slow turn-on and slow turn-off
time feature that is enabled by connecting a resistor and
capacitor from DIM to GND (see the
Typical Application
Circuits
and
the R
DIM
Resistor and C
DIM
Capacitor
Selection
section). This slow turn-on/-off feature causes
the peak-to-peak voltage of the EL outputs to slowly rise
from zero to the maximum set value when the device is
enabled. This feature also causes the peak-to-peak volt-
age of the EL outputs to fall from the maximum set value
to zero when the device is placed into shutdown. The
slow rise and fall of the peak-to-peak EL output voltage
creates a soft fade-on and fade-off of the EL lamp,
rather than an abrupt change in brightness.
Boost Converter
The MAX4990 boost converter consists of an external
inductor from VDD to the LX input, an internal DMOS
switch, an external diode from LX to the CS output, an
external capacitor from the CS output to GND, and the
EL lamp, CLAMP, connected to the EL lamp outputs.
When the DMOS switch is turned on, LX is connected
to GND, and the inductor is charged. When the DMOS
switch is turned off, the energy stored in the inductor is
transferred to the capacitor CCS and the EL lamp.
Note: Keeping SW high shorts LX to GND, causing the
internal die temperature to increase. The MAX4990 is
protected by entering a thermal-shutdown state (See
the
Thermal Short-Circuit Protection
section.)
The MAX4990 boost converter frequency uses an inter-
nal switch oscillator to set the desired frequency of the
boost converter. The boost converter frequency is
adjusted by either 1) the combination of a resistor from
SLEW to GND and an external capacitor from SW to
GND, or 2) by driving a PWM signal directly into the SW
input. When SW is driven with an external PWM signal
at a suggested 90% duty cycle, the boost converter fre-
quency is changed to the frequency of the external
PWM signal. (See the
C
SW
Capacitor Selection
section
for choosing the CSW capacitor value.)
Dimming Control
The MAX4990 features a dimming control input, DIM,
that controls the peak-to-peak voltage on the lamp out-
puts VAand VB. DIM is controlled by a resistor con-
nected from the DIM input to GND, a PWM signal
applied to the DIM input, or a DC voltage applied to the
DIM input. (See the
R
DIM
Resistor and C
DIM
Capacitor
Selection
section.)
The duty cycle of a PWM signal to the DIM input is
internally translated into a DC voltage with the 0 to
+1.22V range. The DIM input accepts the frequency
range of 200kHz to 1MHz. As the duty cycle increases,
the peak-to-peak voltage of the output increases, and
as the duty cycle decreases, the peak-to-peak voltage
of the output decreases.
The peak-to-peak voltage is adjusted by applying a DC
voltage to the DIM input. Increasing the voltage on DIM
increases the peak-to-peak output, and decreasing the
voltage on DIM decreases the peak-to-peak output volt-
age.
The DIM input, in combination with the EN input, con-
trols the shutdown mode of the MAX4990 shutdown.
(See the
Shutdown
section.)
Slow Turn-On, Slow Turn-Off
The MAX4990 provides a slow turn-on/-off feature by
connecting a resistor in parallel with a capacitor con-
nected from the DIM input to GND (see the
R
DIM
Resistor and C
DIM
Capacitor Selection
section). When
EN is driven high, the reference current IB(set by
RSLEW) is used to charge capacitor CDIM. When EN is
driven to GND, IBis removed, and the voltage on the
capacitor CDIM and resistor decays with a time con-
stant of RDIM x CDIM. A slow turn-on effect is seen by
driving EN high. The slow rise and fall of the voltage on
DIM during transitions on the EN input modulates the
peak-to-peak voltage of the EL outputs, creating a soft
fade-on/-off effect at the EL lamp.
Shutdown
The MAX4990 features an enable logic input, EN, to
enable and disable the device. To enable the device,
apply +1.2V or greater to the EN input and +0.35V or
greater to the DIM input. To place the device in shut-
down, apply +0.2V or less to the EN input, and +0.15V
or less to the DIM input.
Undervoltage Lockout (UVL0)
The MAX4990 has a UVLO threshold of +2.1V (typ).
When VDD falls below +2.1V (typ), the device enters a
nonoperative mode.
Thermal Short-Circuit Protection
The MAX4990 enters a nonoperative mode if the inter-
nal die temperature of the device reaches or exceeds
+158°C (typ). The device turns back on when the inter-
nal die temperature cools to +150°C.
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
_______________________________________________________________________________________ 9
MAX4990
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against electro-
static discharges encountered during handling and
assembly. The EL lamp driver outputs of the MAX4990
have extra protection against static electricity. Maxim’s
engineers have developed state-of-the-art structures to
protect these pins against ESD of ±15kV without dam-
age. The ESD structures withstand high ESD in all
states: normal operation, shutdown, and powered
down. After an ESD event, the MAX4990 keep working
without latchup or damage.
ESD protection can be tested in various ways. The
transmitter EL lamp outputs of the MAX4990 are char-
acterized for protection to the following limits:
• ±15kV using the Human Body Model
• ±4kV IEC 61000-4-2 Contact Discharge
• ±15kV IEC 61000-4-2 Air-Gap Discharge
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results.
Human Body Model
Figure 1a shows the Human Body Model, and Figure
1b shows the current waveform it generates when dis-
charged into a low impedance. This model consists of a
100pF capacitor charged to the ESD voltage of interest,
which is then discharged into the test device through a
1.5kΩresistor.
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. However, it does
not specifically refer to integrated circuits. The
MAX4990 assists in designing equipment to meet IEC
61000-4-2 without the need for additional ESD-protec-
tion components.
The major difference between tests done using the
Human Body Model and IEC 61000-4-2 is higher peak
current in IEC 61000-4-2 because series resistance is
lower in the IEC 61000-4-2 model. Hence, the ESD with-
stand voltage measured to IEC 61000-4-2 is generally
lower than that measured using the Human Body
Model. Figure 1c shows the IEC 61000-4-2 model, and
Figure 1d shows the current waveform for IEC 61000-4-
2 ESD Contact Discharge test.
Machine Model
The machine model for ESD tests all pins using a 200pF
storage capacitor and zero discharge resistance.
The objective is to emulate the stress caused when I/O
pins are contacted by handling equipment during test
and assembly. Of course, all pins require this protection.
The Air-Gap test involves approaching the device with a
charged probe. The Contact Discharge method connects
the probe to the device before the probe is energized.
Design Procedure
LX Inductor Selection
The recommended inductor values are 220µH/330µH.
For most applications, series resistance (DCR) should
be below 8Ωfor reasonable efficiency. Do not exceed
the inductor’s saturation current.
RSLEW Resistor Selection
To help reduce audible noise emission by the EL lamp,
the MAX4990 features a slew-rate control input (SLEW)
that allows the user to set the slew-rate of the high-volt-
age outputs, VAand VB, by connecting a resistor,
RSLEW, from the SLEW input to GND. RSLEW precisely
sets the reference current IBthat is used to charge and
discharge the capacitances at the SW input and EL
input, and is used as a reference current for internal cir-
cuitry. The reference current is related to RSLEW by the
following equation: IB= 1V/RSLEW. Decreasing the
value of RSLEW increases IBand increases the slew rate
at the EL lamp output. Increasing the value of RSLEW
decreases IBand decreases the slew rate at the EL lamp
output. The output slew rate is related to RSLEW by the
following equation:
The ideal value for a given design varies depending on
lamp size and mechanical enclosure. Typically, the best
slew rate for minimizing audible noise is between
10V/100µs and 20V/100µs. This results in RSLEW values
ranging from 1.125MΩto 0.5625MΩ. For example, if the
desired slew rate is 20 (V/100µs), this leads to an RSLEW
resistor value in MΩof RSLEW = 11.25/20V = 0.5625MΩ.
Note: Connecting RSLEW to GND will not damage the
device. However, for the device to operate correctly,
RSLEW should be in the 100kΩto 2.2MΩrange.
RSLEW also affects the frequency of the boost converter
(see the
C
SW
Capacitor Selection
), the frequency of the
EL lamp (see the
C
EL
Capacitor Selection
section), and
the peak-to-peak voltage of the EL lamp.
SlewRate V
sR M100
125
μ
⎛
⎝
⎜⎞
⎠
⎟=
()
1
SLEW
.
Ω
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
10 ______________________________________________________________________________________
The peak-to-peak voltage is adjusted by connecting a
resistor from the SLEW input to GND together with a
resistor from the DIM input to GND. The equation relating
the peak-to-peak voltage to the resistors is the following:
RDIM Resistor and CDIM
Capacitor Selection
The MAX4990 provides a slow turn-on/-off feature by
connecting a resistor in parallel with a capacitor con-
nected from the DIM input to GND. The reference cur-
rent IBis used to charge the resistor and capacitor.
When EN is driven to GND, IBis removed, and the volt-
age across the capacitor and resistor decay with a time
constant of RC that provides a slow turn off of the EL
VR
R
P-P DIM
SLEW
=×200
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
______________________________________________________________________________________ 11
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
Cs
100pF
RC
1MΩ
RD
1500Ω
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
Figure 1a. Human Body ESD Test Model
IP 100%
90%
36.8%
tRL TIME
tDL
CURRENT WAVEFORM
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
10%
0
0
AMPS
Figure 1b. Human Body Current Waveform
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
Cs
150pF
RC
50MΩ TO 100MΩRD
330Ω
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
Figure 1c. IEC 61000-4-2 ESD Test Model
tr = 0.7ns TO 1ns 30ns
60ns
t
100%
90%
10%
I
PEAK
I
Figure 1d. IEC 61000-4-2 ESD Generator Current Waveform
Table 1. Inductor Vendors
INDUCTOR VALUE (µH) VENDOR WEBSITE PART
220 TOKO www.tokoam.com D312C 1001BS-221M
330 Coilcraft www.coilcraft.com DO1608C-334ML
470 Coilcraft www.coilcraft.com DO1608C-474ML
220 Coilcraft www.coilcraft.com LPS4018-224ML
330 Coilcraft www.coilcraft.com LPS4018-334ML
470 Coilcraft www.coilcraft.com LPS4018-474ML
220 Cooper Bussmann www.cooperet.com SDH3812-221-R
220 Cooper Bussmann www.cooperet.com SD3110-221-R
MAX4990
lamp outputs. A slow turn-on effect is produced by dri-
ving EN high. Slow turn-on/-off time is related by the fol-
lowing equation:
tON = 2.6 x RDIM x CDIM
tOFF = 1.2 x RDIM x CDIM
For this equation to be valid, RDIM/RSLEW must be
≤1.3.
CCS Capacitor Selection
CCS is the output of the boost converter and provides
the high-voltage source for the EL lamp. Connect a
3.3nF capacitor from CS to GND and place as close to
the CS input as possible. When using an inductor value
larger than 220µH, it may be necessary to increase the
CCS. For a LX= 470µH and CLAMP = 20nF, a CCS
ranging from 3.3nF to 6.8nF is recommended.
CEL Capacitor Selection
The MAX4990 EL lamp output frequency is set by con-
necting a capacitor from the EL input to GND together
with a resistor from SLEW to GND or by driving the EL
input with an external clock (0 to +1.5V). The EL lamp
output frequency is related to the CEL capacitor by the
following equation:
For example, an RSLEW = 375kΩand a CEL capacitor
value of 1000pF equals an EL lamp output frequency of
FEL = 217Hz.
CSW Capacitor Selection
The boost converter switching frequency is set by con-
necting a capacitor from the SW input to GND, together
with the resistance from the SLEW input to GND, or driving
the SW input with an external clock (0 to +1.5V). The
switching frequency of the boost converter is related to the
capacitor from SW to GND by the following equation:
Connect the SW input to GND to turn the switch oscilla-
tor of the boost converter off. Although the optimal fSW
depends on the inductor value, the suggested fSW
range is 20kHz to 150kHz.
Note: Driving SW with a logic-high causes LX to be dri-
ven to GND. Keeping SW high shorts LX to GND, caus-
ing the internal die temperature to increase. The
MAX4990 is protected by entering a thermal-shutdown
state. (See the
Thermal Short-Circuit Protection
section.)
CBCapacitor Selection
Bypass VDD with a 0.1µF ceramic capacitor as close to
the IC as possible and a 4.7µF ceramic capacitor as
close to the inductor as possible
Diode Selection
Connect a diode, D1, from the LX node to CS to rectify
the boost voltage on CS. The diode should be a fast-
recovery diode that is tolerant to +150V.
EL Lamp Selection
EL lamps have a capacitance of approximately 2.5nF to
3.5nF per square inch. The MAX4990 effectively
charges capacitance ranging from 2nF to 20nF.
Applications Information
PCB Layout
Keep PCB traces as short as possible. Ensure that
bypass capacitors are as close to the device as possi-
ble. Use large ground planes where possible.
Chip Information
PROCESS: BiCMOS-DMOS
fRC
SW SLEW SW
=×
361.
fRC
EL SLEW EL
=×
0 0817.
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
12 ______________________________________________________________________________________
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
______________________________________________________________________________________ 13
MAX4990
SLEW
DIGITAL OUTPUT
PWM OR VBIAS
μC
OR ASIC
RSLEW
LX = 220μH
VDD
14
12
13
1VA
N.C.
VB
EN EL LAMP
CLAMP = 10nF
DIM
EL 11
N.C.
SW
CEL
CSW 10
D1CCS = 3.3nF
CB = 0.1μF
CS
VDD
9
N.C.
GND 8
3
2
4
5
6
7LX
4.7μF
MAX4990
SLEW
DIGITAL OUTPUT
μC
OR ASIC
RSLEW
RDIM
CDIM
LX = 220μH
VDD
14
12
13
1VA
N.C.
VB
EN EL LAMP
CLAMP = 10nF
DIM
EL
11
N.C.
SW
CEL
CSW
10
D1CCS = 3.3nF
CB = 0.1μF
CS
VDD
9
N.C.
GND 8
3
2
4
5
6
7LX
4.7μF
Typical Application Circuits
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
14 ______________________________________________________________________________________
6, 8, &10L, DFN THIN.EPS
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
______________________________________________________________________________________ 15
COMMON DIMENSIONS
SYMBOL MIN. MAX.
A 0.70 0.80
D 2.90 3.10
E 2.90 3.10
A1 0.00 0.05
L 0.20 0.40
PKG. CODE N D2 E2 eJEDEC SPEC b[(N/2)-1] x e
PACKAGE VARIATIONS
0.25 MIN.k
A2 0.20 REF.
2.00 REF0.25±0.050.50 BSC2.30±0.1010T1033-1
2.40 REF0.20±0.05- - - - 0.40 BSC1.70±0.10 2.30±0.1014T1433-1
1.50±0.10 MO229 / WEED-3
0.40 BSC - - - - 0.20±0.05 2.40 REFT1433-2 14 2.30±0.101.70±0.10
T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF
T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF
T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF
2.30±0.10 MO229 / WEED-3 2.00 REF0.25±0.050.50 BSC1.50±0.1010T1033-2
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX4990
High-Voltage, ±15kV ESD-Protected
Electroluminescent Lamp Driver
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
SPRINGER
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 8/07 Initial release —
1 11/07 Revise lead–free part number from MAX4990E to MAX4990 1-13
