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19-0886; Rev 0; 8/07
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver
General Description
The MAX4990E high-voltage DC-AC converter is ideal for driving electroluminescent (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 single-cell lithium-ion (Li+) batteries and higher voltage battery chargers. The lamp outputs of the device generate up to 250V peak-topeak output voltage for maximum lamp brightness. The MAX4990E utilizes an inductor-based boost converter 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 connected from SW to GND and an external resistor connected from SLEW to GND. 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 connected from EL to GND and an external resistor connected from SLEW to GND. The MAX4990E uses a proprietary acoustic noisereduction circuit that controls 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 MAX4990E 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 MAX4990E enters a low-power shutdown mode (100nA max) when the EN and DIM inputs are connected to GND. The MAX4990E also enters thermal shutdown if the die temperature rises above +158C. The MAX4990E is available in a space-saving, 14-pin, 3mm x 3mm TDFN package and is specified over the extended -40C to +85C operating temperature range.
Typical Application Circuits appear at end of data sheet.
Features
ESD-Protected EL Lamp Outputs 15kV Human Body Model 4kV IEC 61000-4-2 Contact Discharge 15kV IEC 61000-4-2 Air-Gap Discharge 250VP-P (MAX) Output for Highest Brightness Wide +2.4V to +5.5V Input Voltage Range Resistor-Adjustable Slew-Rate Control for Audible Noise Reduction Externally Driven Lamp and Switching Converter Frequencies Capacitor-Adjustable Lamp and Switching Converter Frequencies Low 100nA Shutdown Current DIM Input for Controlling Output Voltage Through DC Analog Voltage, PWM, or Resistor to GND Capacitor Adjustable for Slow Turn-On/-Off Space-Saving Packages 14-Pin, 3mm x 3mm TDFN
MAX4990E
Applications
Keypad Backlighting MP3 Players LCD Backlighting PDAs/Smartphones Automotive Instrument Clusters
Pin Configuration
N.C. N.C. N.C. 9 *EP 2 EN 3 DIM 4 EL 5 SW 6 VDD 7 GND CS LX 8
TOP VIEW
VA 14
13
12
VB
11
10
MAX4990E
+ 1 SLEW
TDFN-EP
*EP = EXPOSED PAD. CONNECT EP TO GND OR LEAVE UNCONNECTED.
Ordering Information
PART MAX4990ETD+ PIN-PACKAGE 14 TDFN-EP (3mm x 3mm) TOP MARK ADL PKG CODE T1433-2 15kV PROTECTION Yes DIM CONTROL Yes SLEW-RATE CONTROL Yes
Note: The device operates over the -40C to +85C operating temperature range.
+Denotes a lead-free package. EP = Exposed paddle. 1
________________________________________________________________ Maxim Integrated Products
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.
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
ABSOLUTE MAXIMUM RATINGS
(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 = +70C) 14-Pin TDFN (derate 24.4mW/C above +70C) ...... 1951mW JA .................................................................................41C/W Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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.
ELECTRICAL CHARACTERISTICS
(VDD = +2.4V to +5.5V, CLAMP = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +3.0V and TA = +25C.) (Note 1)
PARAMETER Power-Supply Voltage Power-Supply Current Shutdown Supply Current Shutdown Inductor Supply Current Undervoltage Lockout UVLO Hysteresis EL OUTPUTS (VA - VB) VDD = +3V, DIM = +0.5V Peak-to-Peak Output Voltage VA - VB VDD = +3V, DIM = +1V VDD = +3V, DIM = +1.3V Pulldown Switch On-Resistance Pullup Switch On-Resistance RONPD RONPU ILKG_NMOS Switch Off-Leakage ILKG_PMOS VA, VB Differential Resistor EL Lamp Switching Frequency ESD Protection (VA, VB Only) VAB_RES fEL ISINK = 1mA, VCS = +10V, VA, VB < +0.6V, VDD = +3V VCS = +125V, ISOURCE = 1mA VA = +125V, VB = +125V, shutdown mode, VCS = +125V VA = 0V, VB = unconnected, shutdown mode, VCS = +125V VA = +0.1V, VB = 0V, shutdown mode, CS = unconnected CEL = 872pF, RSLEW = 375k Human Body Model IEC 61000-4-2 Contact Discharge IEC 61000-4-2 Air-Gap Discharge 84 170 210 50 700 -1 -60 2 210 250 15 4 15 kV 100 200 250 165 1500 122 230 280 500 2200 +1 A +60 7 290 M Hz V SYMBOL VDD IDD ISHDN ILXSHDN VLO VHYST RSLEW = 375k, slope = 30V/100s; fEL = 200Hz, VA - VB = 250VP-P EN = 0V, DIM = 0V, TA = +25C EN = 0V, DIM = 0V, TA = -40C to +85C EN = 0V, DIM = 0V, LX = VDD, CS = VDD VDD rising 1.8 2.1 125 25 CONDITIONS MIN 2.4 TYP MAX 5.5 350 100 300 1500 2.3 UNITS V A nA nA V mV
2
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High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.4V to +5.5V, CLAMP = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +3.0V and TA = +25C.) (Note 1)
PARAMETER BOOST CONVERTER VDD = +3V, DIM = +0.5V forced externally Output Peak Voltage Boost Switching Frequency Switch On-Resistance LX Leakage Current CS Input Current CONTROL INPUT SW Input Voltage-High Threshold Input Voltage-Low Threshold Input Low Current Input High Current CONTROL INPUT EL Input Voltage-High Threshold Input Voltage-Low Threshold Input Low Current Input High Current CONTROL INPUT SLEW Force Voltage High-Voltage Output Slew Rate CONTROL INPUT DIM Input Logic-High Voltage Input Logic-Low Voltage Input Low Current Input High Current PWM Frequency Range Low-Peak Detector Threshold Low-Peak Detector Hysteresis CONTROL INPUT EN Input Voltage-High Threshold Input Voltage-Low Threshold Input Low Current Input High Current VIH_EN VIL_EN IIL_EN IIH_EN -1 -1 1.2 0.2 +1 +1 V V A A VLPD VLPD_HYST 0.15 100 VIH_DIM VIL_DIM IIL_DIM IIH_DIM Output voltage (max) Output voltage (off) VDIM = 0V, RSLEW = 375k VDIM = VDD 2.22 -1 0.2 to 1 0.35 1.3 0.15 3.0 +1 V V A A MHz V mV VFORCE ISOURCE = 20A RSLEW = 375k 0.89 0.95 30 1.04 V V/100s VIH_CEL VIL_CEL IIL_CEL IIH_CEL RSLEW = 375k RSLEW = 375k RSLEW = 375k RSLEW = 375k 1.08 0.22 1.2 1.2 1.32 0.39 1.87 1.87 V V A A VIH_SW VIL_SW IIL_SW IIH_SW RSLEW = 375k RSLEW = 375k RSLEW = 375k, CS = +40V, EL = VDD, DIM = VDD RSLEW = 375k, CS = +40V, EL = VDD, DIM = VDD 0.9 0.43 43 5.0 0.98 0.49 1.06 0.55 77 7.5 V V A A VCS fSW RLX ILX ICS VDD = +3V, DIM = +1V forced externally VDD = +3V, DIM = +1.3V forced externally CSW = 96pF, RSLEW = 375k ISINK = 25mA, VDD = +3V VLX = +125V No load, VCS = +125V, EN = 0V, DIM = 0V -1 42 85 105 80 50 100 125 100 61 115 140 120 20 +1 50 kHz A A V SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX4990E
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3
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.4V to +5.5V, CLAMP = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +3.0V and TA = +25C.) (Note 1)
PARAMETER THERMAL SHUTDOWN Thermal Shutdown Thermal Shutdown Hysteresis 158 8 C C SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: Specifications at TA = -40C are guaranteed by design and not production.
Typical Operating Characteristics
(VDD = +3.6V, CLAMP = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), RSLEW = 390k, DIM = VDD, CSW = 100pF, CEL = 1.2nF, TA = +25C, unless otherwise noted.)
TOTAL INPUT CURRENT vs. SUPPLY VOLTAGE
MAX4990E toc01
TOTAL INPUT CURRENT vs. TEMPERATURE
MAX4990E toc02
TOTAL INPUT CURRENT AND PEAK-TO-PEAK OUTPUT VOLTAGE vs. BOOST CONVERTER FREQUENCY
80
MAX4990E toc03
20 18 TOTAL INPUT CURRENT (mA) 16 14 12 10 8 6 4 2 0 2.4 3.0 3.6 4.2 4.8 5.4 SUPPLY VOLTAGE (V)
20
TOTAL INPUT CURRENT (mA)
TOTAL INPUT CURRENT (mA)
16
60 CCS = 2.2nF 40 CCS = 4.7nF 20 CCS = 4.7nF
225
12
150
8
75
4
0 -40 -15 10 35 60 85 TEMPERATURE (C)
0 40 80
CCS = 2.2nF 120 160
0 200
BOOST CONVERTER FREQUENCY (kHz)
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
MAX4990E toc04
SHUTDOWN CURRENT vs. TEMPERATURE
DIM = EN = 0V
MAX4990E toc05
PEAK-TO-PEAK OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
PEAK-TO-PEAK OUTPUT VOLTAGE (V) DIM = 1.3V DIM = 1.0V 200 150 100 50 0 DIM = 0.8V DIM = 0.6V
MAX4990E toc06
1.0
DIM = EN = 0V
100
300 250
SHUTDOWN CURRENT (nA)
SHUTDOWN CURRENT (nA)
0.8
10
0.6
1
0.4
0.2
0.1
0 2.4 3.0 3.6 4.2 4.8 5.4 SUPPLY VOLTAGE (V)
0.01 -40 -15 10 35 60 85 TEMPERATURE (C)
2.4
3.0
3.6
4.2
4.8
5.4
SUPPLY VOLTAGE (V)
4
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PEAK-TO-PEAK OUTPUT VOLTAGE (V)
- - - - PEAK-TO-PEAK OUTPUT VOLTAGE 90% DUTY CYCLE
300
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
Typical Operating Characteristics (continued)
(VDD = +3.6V, CLAMP = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), RSLEW = 390k, DIM = VDD, CSW = 100pF, CEL = 1.2nF, TA = +25C, unless otherwise noted.)
PEAK-TO-PEAK OUTPUT VOLTAGE vs. TEMPERATURE
MAX4990E toc07
PEAK-TO-PEAK OUTPUT VOLTAGE vs. DIM VOLTAGE
VDD = 4.5V
MAX4990E toc08
PEAK-TO-PEAK OUTPUT VOLTAGE vs. DIM DUTY CYCLE
MAX4990E toc09
210 PEAK-TO-PEAK OUTPUT VOLTAGE (V) 205 200 195 190 185 180 -40 -15 10 35 60
300 PEAK-TO-PEAK OUTPUT VOLTAGE (V) 250 200 150 100 50
300 PEAK-TO-PEAK OUTPUT VOLTAGE (V) 250 200 150 100 fDIM = 1MHz 50 0 fDIM = 200kHz
85
0 0.35
0.54
0.73
0.92
1.11
1.30
20
40
60
80
TEMPERATURE (C)
DIM VOLTAGE (V)
DIM DUTY CYCLE (%)
RMS OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
MAX4990E toc10
AVERAGE OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
MAX4990E toc11
AVERAGE OUTPUT VOLTAGE vs. TEMPERATURE
-100 AVERAGE OUTPUT VOLTAGE (mV) -200 -300 -400 -500 -600 -700 -800 -900 -1000
MAX4990E toc12
120 100 RMS OUTPUT VOLTAGE (V) 80 60 40 20 0 2.4 3.0 3.6 4.2 4.8 5.4 SUPPLY VOLTAGE (V)
0 -100 AVERAGE OUTPUT VOLTAGE (mV) -200 -300 -400 -500 -600 -700 -800 -900 -1000 2.4 3.0 3.6 4.2 4.8 5.4 SUPPLY VOLTAGE (V)
0
-40
-15
10
35
60
85
TEMPERATURE (C)
EL SWITCHING FREQUENCY vs.CEL
MAX4990E toc13
EL SWITCHING FREQUENCY vs. SUPPLY VOLTAGE
MAX4990E toc14
EL SWITCHING FREQUENCY vs. TEMPERATURE
MAX4990E toc15
500 EL SWITCHING FREQUENCY (Hz)
RSLEW = 390k
190 EL SWITCHING FREQUENCY (Hz)
190 EL SWITCHING FREQUENCY (Hz)
400
185
185
300
180
180
200
175
100
175
0 0.5 1.0 1.5 CEL (nF) 2.0 2.5
170 2.4 3.0 3.6 4.2 4.8 5.4 SUPPLY VOLTAGE (V)
170 -40 -15 10 35 60 85 TEMPERATURE (C)
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5
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
Typical Operating Characteristics (continued)
(VDD = +3.6V, CLAMP = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), RSLEW = 390k, DIM = VDD, CSW = 100pF, CEL = 1.2nF, TA = +25C, unless otherwise noted.)
BOOST CONVERTER FREQUENCY vs. SUPPLY VOLTAGE
MAX4990E toc17
BOOST CONVERTER FREQUENCY vs. CSW
RSLEW = 390k
MAX4990E toc16
BOOST CONVERTER FREQUENCY vs. TEMPERATURE
BOOST CONVERTER FREQUENCY (kHz)
MAX4990E toc18
160 BOOST CONVERTER FREQUENCY (kHz)
110 BOOST CONVERTER FREQUENCY (kHz)
110
120
105
105
80
100
100
40
95
95
0 80 115 150 CSW (pF) 185 220
90 2.4 3.0 3.6 4.2 4.8 5.4 SUPPLY VOLTAGE (V)
90 -40 -15 -10 35 60 85 TEMPERATURE (C)
OUTPUT VOLTAGE SLOPE vs. RSLEW
MAX4990E toc19
OUTPUT VOLTAGE SLOPE vs. SUPPLY VOLTAGE
MAX4990E toc20
OUTPUT VOLTAGE SLOPE vs. TEMPERATURE
MAX4990E toc21
40 OUTPUT VOLTAGE SLOPE (V/100s) 35 30 25 20 15 10 5 0 300 400 500 700 RSLEW (k) 600 800
32 OUTPUT VOLTAGE SLOPE (V/100s)
32 OUTPUT VOLTAGE SLOPE (V/100s)
30
30
28
28
26
26
24
24
22 900 1000 2.4 3.0 3.6 4.2 4.8 5.4 SUPPLY VOLTAGE (V)
22 -40 -15 10 35 80 85 TEMPERATURE (C)
SLOW TURN-ON/-OFF TIME vs. CDIM
RDIM = 390k
MAX4990E toc22
BRIGHTNESS AND TOTAL INPUT CURRENT vs. SUPPLY VOLTAGE
25
MAX4990E toc23
TYPICAL VA, VB, AND VA - VB WAVEFORMS
30
MAX4990E toc24
4.0 3.5 SLOW TURN ON/OFF TIME (s) 3.0 2.5 2.0 1.5 1.0 0.5 0 0
- - - - SUPPLY CURRENT CLAMP = 20nF
TOTAL INPUT CURRENT (mA)
20 BRIGHTNESS (cd/m2)
26
tON
VA - VB 100V/div
15
22
10
18
VA 50V/div
5 tOFF 0 0.6 1.2 1.8 CDIM (F) 2.4 3.0 3.6 2.4 3.0 4.2 4.8 SUPPLY VOLTAGE (V) 3.6 5.4
14
VB 50V/div 1ms/div
10
6
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High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver
Pin Description
PIN 1 2 NAME SLEW EN FUNCTION 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. 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, 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. 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 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-VA side of EL lamp. High-Voltage EL Panel Output. Connect to non-VB side of EL lamp. Exposed Pad. Connect exposed pad to GND.
MAX4990E
3
DIM
4
EL
5
SW
6 7 8 9, 11, 13 10 12 14 EP
VDD GND LX N.C. CS VB VA EP
Detailed Description
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 single cell Li+ batteries and higher voltage battery chargers. 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 converter that allows for the use of a 220H inductor 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 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 converter to take the frequency of the PWM signal.
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 connected from EL to GND and an external resistor connected from SLEW to GND. The MAX4990E allows programmability 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 noisereduction 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 MAX4990E enters a low-power shutdown mode (100nA max) when EN and DIM inputs are connected
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7
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
Functional Diagram
VDD SW SWITCH OSCILLATOR TIMEOUT + EL EL OSCILLATOR REF CS N LX
SLEW
V-I CONVERTER + LOW-POWER SHUTDOWN PWM CONVERTER LOW PEAK DETECTOR DMOS DRIVER
VSENSE
HIGH ESD PROTECTION H-BRIDGE HIGH ESD PROTECTION
VA
EN
VB
DIM
SHUTDOWN THERMAL SHUTDOWN GND UVLO TIMEOUT LOW-POWER SHUTDOWN NO-OPERATION SIGNAL
MAX4990E
to GND. The MAX4990E also enters thermal shutdown if the die temperature rises above +158C. 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 connected 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 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 combination 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 C EL capacitor value.) The peak-to-peak voltage of the EL lamp output is varied from 70VP-P to 250VP-P by applying an external DC voltage ranging from +0.35V to +1.3V to the DIM input.
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.
8
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High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver
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 voltage. 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 MAX4990E 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 voltage 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. 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 RDIM Resistor and CDIM 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 voltage. The DIM input, in combination with the EN input, controls the shutdown mode of the MAX4990E shutdown. (See the Shutdown section.)
MAX4990E
Slow Turn-On, Slow Turn-Off
The MAX4990E provides a slow turn-on/-off feature by connecting a resistor in parallel with a capacitor connected from the DIM input to GND (see the R DIM Resistor and CDIM Capacitor Selection section). When EN is driven high, the reference current I B (set by RSLEW) is used to charge capacitor CDIM. When EN is driven to GND, IB is removed, and the voltage on the capacitor CDIM and resistor decays with a time constant 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.
Boost Converter
The MAX4990E 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 MAX4990E is protected by entering a thermal-shutdown state (See the Thermal Short-Circuit Protection section.) The MAX4990E boost converter frequency uses an internal 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 frequency is changed to the frequency of the external PWM signal. (See the CSW Capacitor Selection section for choosing the CSW capacitor value.)
Shutdown
The MAX4990E 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 shutdown, apply +0.2V or less to the EN input, and +0.15V or less to the DIM input.
Undervoltage Lockout (UVL0)
The MAX4990E 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 MAX4990E enters a nonoperative mode if the internal die temperature of the device reaches or exceeds +158C (typ). The device turns back on when the internal die temperature cools to +150C.
9
Dimming Control
The MAX4990E features a dimming control input, DIM, that controls the peak-to-peak voltage on the lamp outputs VA and VB. DIM is controlled by a resistor con-
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High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
15kV ESD Protection
As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The EL lamp driver outputs of the MAX4990E 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 damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, the MAX4990E keep working without latchup or damage. ESD protection can be tested in various ways. The transmitter EL lamp outputs of the MAX4990E are characterized 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
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 220H/330H. For most applications, series resistance (DCR) should be below 8 for reasonable efficiency. Do not exceed the inductor's saturation current. RSLEW Resistor Selection To help reduce audible noise emission by the EL lamp, the MAX4990E features a slew-rate control input (SLEW) that allows the user to set the slew-rate of the high-voltage outputs, V A and V B, by connecting a resistor, RSLEW, from the SLEW input to GND. RSLEW precisely sets the reference current IB that is used to charge and discharge the capacitances at the SW input and EL input, and is used as a reference current for internal circuitry. The reference current is related to R SLEW by the following equation: I B = 1V/R SLEW . Decreasing the value of R SLEW increases I B and increases the slew rate at the EL lamp output. Increasing the value of RSLEW decreases IB and decreases the slew rate at the EL lamp output. The output slew rate is related to RSLEW by the following equation:
V 11.25 SlewRate = 100s RSLEW (M) 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/100s and 20V/100s. This results in RSLEW values ranging from 1.125M to 0.5625M. For example, if the desired slew rate is 20 (V/100s), this leads to an RSLEW resistor value in M of RSLEW = 11.25/20V = 0.5625M. Note: Connecting RSLEW to GND will not damage the device. However, for the device to operate correctly, RSLEW should be in the 100k to 2.2M range. RSLEW also affects the frequency of the boost converter (see the CSW Capacitor Selection), the frequency of the EL lamp (see the CEL Capacitor Selection section), and the peak-to-peak voltage of the EL lamp.
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 discharged 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 1.5k resistor.
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 MAX4990E assists in designing equipment to meet IEC 61000-4-2 without the need for additional ESD-protection 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 withstand 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 61000-42 ESD Contact Discharge test.
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High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
RC 1M CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 1500 DISCHARGE RESISTANCE DEVICE UNDER TEST HIGHVOLTAGE DC SOURCE RC 50M TO 100M CHARGE-CURRENTLIMIT RESISTOR RD 330 DISCHARGE RESISTANCE DEVICE UNDER TEST
Cs 100pF
STORAGE CAPACITOR
Cs 150pF
STORAGE CAPACITOR
Figure 1a. Human Body ESD Test Model
Figure 1c. IEC 61000-4-2 ESD Test Model
IP 100% 90% AMPS 36.8% 10% 0 0 tRL TIME
Ir
PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) IPEAK
I 100% 90%
10% tDL CURRENT WAVEFORM tr = 0.7ns TO 1ns 30ns 60ns t
Figure 1b. Human Body Current Waveform
Figure 1d. IEC 61000-4-2 ESD Generator Current Waveform
Table 1. Inductor Vendors
INDUCTOR VALUE (H) 220 330 470 220 330 470 VENDOR TOKO Coilcraft Coilcraft Coilcraft Coilcraft Coilcraft WEBSITE www.tokoam.com www.coilcraft.com www.coilcraft.com www.coilcraft.com www.coilcraft.com www.coilcraft.com PART D312C 1001BS-221M DO1608C-334ML DO1608C-474ML LPS4018-224ML LPS4018-334ML LPS4018-474ML
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: VP-P = 200 x RDIM RSLEW
RDIM Resistor and CDIM Capacitor Selection
The MAX4990E provides a slow turn-on/-off feature by connecting a resistor in parallel with a capacitor connected from the DIM input to GND. The reference current IB is used to charge the resistor and capacitor. When EN is driven to GND, IB is removed, and the voltage across the capacitor and resistor decay with a time constant of RC that provides a slow turn off of the EL
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11
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
lamp outputs. A slow turn-on effect is produced by driving EN high. Slow turn-on/-off time is related by the following equation: tON = 2.6 x RDIM x CDIM tOFF = 1.2 x RDIM x CDIM For this equation to be valid, R DIM /R SLEW must be 1.3. Connect the SW input to GND to turn the switch oscillator of the boost converter off. Although the optimal fSW depends on the inductor value, the suggested f SW range is 20kHz to 150kHz. Note: Driving SW with a logic-high causes LX to be driven to GND. Keeping SW high shorts LX to GND, causing the internal die temperature to increase. The MAX4990E is protected by entering a thermal-shutdown state. (See the Thermal Short-Circuit Protection section.)
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 220H, it may be necessary to increase the C CS. For a LX = 470H and C LAMP = 20nF, a C CS ranging from 3.3nF to 6.8nF is recommended. CEL Capacitor Selection The MAX4990E EL lamp output frequency is set by connecting 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:
0.0817 fEL = RSLEW x CEL For example, an RSLEW = 375k and a CEL capacitor value of 1000pF equals an EL lamp output frequency of FEL = 217Hz.
CB Capacitor Selection Bypass VDD with a 0.1F ceramic capacitor as close to the IC as possible and a 4.7F 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 fastrecovery 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 MAX4990E 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 possible. Use large ground planes where possible.
CSW Capacitor Selection The boost converter switching frequency is set by connecting 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:
fSW = 3.61 RSLEW x CSW
Chip Information
PROCESS: BiCMOS-DMOS
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High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver
Typical Application Circuits
RSLEW 1 2 3 CEL CSW 4 5 6 CB = 0.1F VDD LX = 220H 4.7F 7 SLEW EN DIM EL SW VDD GND VA N.C. VB 14 13 12 11 10 9 8 D1 CCS = 3.3nF EL LAMP CLAMP = 10nF
MAX4990E
DIGITAL OUTPUT PWM OR VBIAS C OR ASIC
MAX4990E
N.C. CS N.C. LX
RSLEW
1 2
SLEW EN DIM
VA N.C. VB
14 13 12 11 10 9 8 D1 CCS = 3.3nF EL LAMP CLAMP = 10nF
DIGITAL OUTPUT
CDIM
3
C OR ASIC
CEL RDIM CSW
MAX4990E
4 5 6 EL SW VDD GND LX = 220H
N.C. CS N.C. LX
CB = 0.1F VDD
7
4.7F
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13
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver MAX4990E
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.) 6, 8, &10L, DFN THIN.EPS 14 ______________________________________________________________________________________
High-Voltage, 15kV ESD-Protected Electroluminescent Lamp Driver
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.)
MAX4990E
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40
PACKAGE VARIATIONS PKG. CODE T633-2 T833-2 T833-3 T1033-1 T1033-2 T1433-1 T1433-2 N 6 8 8 10 10 14 14 D2 1.500.10 1.500.10 1.500.10 1.500.10 1.500.10 1.700.10 1.700.10 E2 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.65 BSC 0.65 BSC 0.50 BSC 0.50 BSC 0.40 BSC 0.40 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEEC MO229 / WEED-3 MO229 / WEED-3 ------b 0.400.05 0.300.05 0.300.05 0.250.05 0.250.05 0.200.05 0.200.05 [(N/2)-1] x e 1.90 REF 1.95 REF 1.95 REF 2.00 REF 2.00 REF 2.40 REF 2.40 REF
0.25 MIN. 0.20 REF.
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
(c) 2007 Maxim Integrated Products
SPRINGER
is a registered trademark of Maxim Integrated Products, Inc.

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