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19-4466; Rev 0; 2/09
KIT ATION EVALU ILABLE AVA
Dual Electroluminescent Lamp Driver
General Description
The MAX14514 is a high-voltage DC-AC converter ideal for driving two electroluminescent (EL) lamps. The MAX14514 features a +2.7V to +5.5V input range that allows the device to accept a wide variety of voltage sources, including single-cell lithium-ion (Li+) batteries. The lamp outputs of the device generate up to 300VP-P for maximum lamp brightness. The MAX14514 utilizes an inductor-based boost converter to generate the high voltage necessary to drive EL lamps and allows the use of a 220H inductor to effectively drive total combined lamp sizes of up to 20nF. The MAX14514 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 panels. An external resistor controls the slewrate of the rising and falling edges of the AC drive waveform to reduce audible noise output. The high-voltage outputs are ESD protected up to 15kV Human Body Model, 4kV IEC 61000-4-2 Air Gap Discharge, and 4kV IEC 61000-4-2 Contact Discharge. The MAX14514 features dimming/enable controls (DIM1, DIM2) for each output to allow the user to set the peak-to-peak output voltage with a PWM signal, a DC analog voltage, or a resistor connected from DIM_ to GND. The MAX14514 also provides a slow turn-on/off feature that slowly ramps the output voltage applied to the lamp when enabled or disabled. The MAX14514 enters a low-power shutdown mode when the EN and DIM_ inputs are connected to GND. The device also features thermal shutdown if the die temperature exceeds +158C (typ). The MAX14514 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.
Features
Dual 15kV ESD-Protected EL Lamp Outputs 300VP-P Maximum Output for Highest Brightness +2.7V to +5.5V Input Voltage Range Resistor Adjustable Slew-Rate Control Resistor Adjustable Lamp and Switching Converter Frequencies DIM Input for Controlling Output Voltage Through DC Analog Voltage, PWM, or Resistor to GND Capacitor Adjustable Soft Turn-On/-Off Low 150nA Shutdown Current Thermal Shutdown Space Saving, 14-Pin, 3mm x 3mm TDFN Package
MAX14514
Ordering Information
PART MAX14514ETD+ TEMP RANGE -40C to +85C PIN-PACKAGE 14 TDFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad.
Pin Configuration
SLEW COM
TOP VIEW
CS 9 *EP 6 VDD
EN
Applications
Keypad Backlighting LCD Backlighting PDAs/Smartphones Automotive Instrument Clusters
14
13
12
11
10
MAX14514
+
1 DIM1 2 DIM2 3 CAP 4 EL 5 SW
TDFN-EP (3mm x 3mm)
*EP = EXPOSED PAD. CONNECT EP TO GND OR LEAVE UNCONNECTED.
________________________________________________________________ Maxim Integrated Products
GND
LX 8 7
V1
V2
1
For information on other Maxim products, visit Maxim's website at www.maxim-ic.com.
Dual Electroluminescent Lamp Driver MAX14514
Typical Application Circuit
BASEBAND/PMIC
RSLEW DIM1 DIM2 CCAP CAP CEL EL CSW SW COM CS CCS = 3.3nF GND LX V1 SLEW EN
MAX14514
V2 EL LAMP CLAMP = 10nF EL LAMP CLAMP = 10nF
VDD VDD 0.1F
VBAT 4.7F
LX = 220H
2
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Dual Electroluminescent Lamp Driver
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND.) VDD ........................................................................-0.3V to +6.0V CS, LX...................................................................-0.3V to +160V V1, V2, COM................................................-0.3V to (VCS + 0.3V) SW, EL, DIM_, SLEW, CAP, EN ..................-0.3V to (VDD + 0.3V) Continuous Power Dissipation (TA = +70C) 14-Pin TDFN (derate 24.4mW/C above +70C) .......1951mW Junction-to-Case Thermal Resistance (JC) (Note 1) 14-Pin TDFN ...................................................................8C/W Junction-to-Ambient Thermal Resistance (JA) (Note 1) 14-Pin TDFN .................................................................41C/W Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
MAX14514
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
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 = +2.7V to +5.5V, CLAMP_TOTAL = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), TA = -40C to +85C, unless otherwise noted. Typical values are at VDD = +3.0V, TA = +25C.) (Note 2)
PARAMETER Input Supply Voltage Input Supply Current Shutdown Supply Current Shutdown Inductor Supply Current Undervoltage Lockout Undervoltage Lockout Hysteresis EL OUTPUTS (V1, V2, COM) VDIM_ = +0.5V Peak-to-Peak Output Voltage V1, V2 High-Side Switch OnResistance V1, V2 Low-Side Switch OnResistance COM High-Side Switch OnResistance COM Low-Side Switch OnResistance High-Side Switch Off-Leakage Low-Side Switch Off-Leakage EL Lamp Switching Frequency ESD Protection (COM, V1, V2 Only) V_ - VCOM VDD = +3V VDIM_ = +1V VDIM_ = +1.3V RONHS_VN RONLS_VN ISOURCE = 1mA ISINK = 1mA 105 210 250 130 260 300 1.5 0.7 0.7 0.4 -1 -1 210 250 15 4 4 kV 162 310 350 3.0 2.0 1.5 1.0 +1 +1 290 k k k k A A Hz V SYMBOL VDD IIN ISHDN ILX_SHDN VUV VUV_HYST RSLEW = 375k, FEL = 200Hz, (V1,V2) - VCOM = 300VP-P EN = GND TA = +25C TA = -40C to +85C 40 CONDITIONS MIN 2.7 TYP MAX 5.5 700 150 400 1.5 1.8 2.1 125 2.3 UNITS V A nA A V mV
EN = GND, LX = VDD, CS = VDD VDD falling
RONHS_COM ISOURCE = 1mA RONLS_COM ISINK = 1mA RONHS_LEAK V1, V2, VCOM = 0, VCS = 150V RONLS_LEAK V1, V2, VCOM = 150V, VCS = 150V fEL CEL = 872pF, RSLEW = 375k Human Body Model IEC 61000-4-2 Contact Discharge IEC 61000-4-2 Air-Gap Discharge
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3
Dual Electroluminescent Lamp Driver MAX14514
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +5.5V, CLAMP_TOTAL = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), TA = -40C to +85C, unless otherwise noted. Typical values are at VDD = +3.0V, TA = +25C.) (Note 2)
PARAMETER BOOST CONVERTER VDIM_ = +0.5V Output Regulation 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 (CAP) CAP Switching Frequency Slow Turn-On Time Fast Turn-On CAP Threshold Nonfast Turn-On CAP Threshold Input Leakage Current CONTROL INPUT (SLEW) Force Voltage High-Voltage Output Slew Rate CONTROL INPUTS (DIM1, DIM2) Input High Voltage Input Low Voltage Input Low Current Input High Current PWM Frequency Range Low-Peak Detector Threshold Low-Peak Detector Hysteresis VLPD VLPD_HYST 0.13 100 VIH_DIM__ VIL_DIM__ IIL_DIM__ IIH_DIM__ Max output voltage Min output voltage VDIM_ = 0, RSLEW = 375k VDIM_ = VDD 2.2 -1 0.2 to 1 0.35 2.6 1.3 0.15 3.0 +1 V V A A MHz V mV VFORCE RSLEW = 375k RSLEW = 375k 0.9 0.98 32 1.05 V V/100s fCAP tSLOW_ON VNONFAST_CAP IIH_CAP RSLEW = 375k, CCAP = 1.25nF RSLEW = 375k, CCAP = 1.25nF VDD - 0.35 1.4 Normal operation Shutdown mode 0.3 -100 1 100 180 300 0.3 410 Hz s V V A nA VIH_CEL VIL_CEL IIL_CEL IIH_CEL RSLEW = 375k RSLEW = 375k RSLEW = 375k RSLEW = 375k 1.08 0.22 1.3 1.3 1.32 0.39 1.88 1.88 V V A A VIH_CSW VIL_CSW IIL_CSW IIH_CSW RSLEW = 375k RSLEW = 375k RSLEW = 375k, VCS = +78V, CEL = VDD, VDIM_ = VDD RSLEW = 375k, VCS = +78V, CEL = VDD, VDIM_ = VDD 0.9 0.43 43 5 0.98 0.49 1.06 0.55 79 7.5 V V A A VCS fSW RLX ILX ICS VDD = +3V VDIM_ = +1V VDIM_ = +1.3V CSW = 96pF, RSLEW = 375k ISINK = 25mA, VDD = +3V VLX = +150V No load, VCS = +150V, VEN = 0, VDIM_ = 0 -1 52 105 125 80 65 130 150 100 81 155 175 120 20 +1 50 kHz A A V SYMBOL CONDITIONS MIN TYP MAX UNITS
VFAST_CAP RSLEW = 375k RSLEW = 375k CAP = VDD, RSLEW = 375k
4
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Dual Electroluminescent Lamp Driver
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +5.5V, CLAMP_TOTAL = 10nF, CCS = 3.3nF, LX = 220H (ISAT = 170mA, RS = 5.5), TA = -40C to +85C, unless otherwise noted. Typical values are at VDD = +3.0V, TA = +25C.) (Note 2)
PARAMETER CONTROL INPUT (EN) Input Logic-High Voltage Input Logic-Low Voltage THERMAL SHUTDOWN Thermal Shutdown Thermal Shutdown Hysteresis 158 8 C C VIH_EN VIL_EN 1.4 0.3 V V SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX14514
Note 2: All devices are 100% production tested at TA = +25C. All temperature limits are guaranteed by design.
Typical Operating Characteristics
(VDD = +3.6V, TA = +25C, unless otherwise noted.)
TOTAL INPUT CURRENT vs. SUPPLY VOLTAGE
MAX14514 toc01
TOTAL INPUT CURRENT vs. TEMPERATURE
MAX14514 toc02
INPUT CURRENT AND PEAK-TO-PEAK OUTPUT VOLTAGE vs. BOOST CONVERTER FREQUENCY
80 PEAK-TO-PEAK OUTPUT 90% DUTY CYCLE TOTAL INPUT CURRENT (mA) 60 225
MAX14514 toc03
25
25
300 PEAK-TO-PEAK OUTPUT VOLTAGE (V)
TOTAL INPUT CURRENT (mA)
15
TOTAL INPUT CURRENT (mA)
20
20
15
40
150
10
10
5
5
20
75
0 2.7 3.4 4.1 4.8 5.5 SUPPLY VOLTAGE (V)
0 -40 -15 10 35 60 85 TEMPERATURE (C)
0 40 80 120 160 200 BOOST CONVERTER FREQUENCY (kHz)
0
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
MAX14514 toc04
SHUTDOWN CURRENT vs. TEMPERATURE
MAX14514 toc05
PEAK-TO-PEAK OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
DIM = 1V PEAK-TO-PEAK OUTPUT VOLTAGE (V) 200
MAX14514 toc06
0.4 DIM1 = DIM2 = EN = 0V 0.35 SHUTDOWN CURRENT (nA) 0.3 0.25 0.2 0.15 0.1 0.05 0 2.7 3.4 4.1 4.8
100 DIM1 = DIM2 = EN = 0V SHUTDOWN CURRENT (nA) 10
250
1
150
DIM_ = 0.7V
0.1
100 DIM_ = 0.4V 50 DIM = 0.5V
0.01
0.001 5.5 -40 -15 10 35 60 85 SUPPLY VOLTAGE (V) TEMPERATURE (C)
0 2.7 3.4 4.1 4.8 5.5 SUPPLY VOLTAGE (V)
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5
Dual Electroluminescent Lamp Driver MAX14514
Typical Operating Characteristics (continued)
(VDD = +3.6V, TA = +25C, unless otherwise noted.)
PEAK-TO-PEAK OUTPUT VOLTAGE vs. TEMPERATURE
MAX14514 toc07
PEAK-TO-PEAK OUTPUT VOLTAGE vs. DIM VOLTAGE
DIM1 = DIM2 PEAK-TO-PEAK OUTPUT VOLTAGE (V) VDD = 5.5V 200 VDD = 4.6V 150 VDD = 3.6V 100 VDD = 2.7V
MAX14514 toc08
PEAK-TO-PEAK OUTPUT VOLTAGE vs. DIM DUTY CYCLE
PEAK-TO-PEAK OUTPUT VOLTAGE (V) DIM1 = DIM2 VDD = 5.5V 200
MAX14514 toc09
250 PEAK-TO-PEAK OUTPUT VOLTAGE (V)
250
250 fDIM = 1MHz fDIM = 200kHz
200
150
150
100
100
50
50
50
0 -40 -15 10 35 60 85 TEMPERATURE (C)
0 0.35 0.85 DIM VOLTAGE (V) 1.35
0 20 40 60 80 DUTY CYCLE (%)
RMS OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
MAX14514 toc10
AVERAGE OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
MAX14514 toc11
AVERAGE OUTPUT VOLTAGE vs. TEMPERATURE
MAX14514 toc12
90 80 RMS OUTPUT VOLTAGE (V) 70 60 50 40 30 20 10 0 2.7 3.4 4.1 4.8
700 AVERAGE OUTPUT VOLTAGE (mV) 600 500 400 300 200 100 0
700 AVERAGE OUTPUT VOLTAGE (mV) 600 500 400 300 200 100 0
5.5
2.7
3.4
4.1
4.8
5.5
-40
-15
10
35
60
85
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
EL SWITCHING FREQUENCY vs. CEL
MAX14514 toc13
EL SWITCHING FREQUENCY vs. SUPPLY VOLTAGE
234 EL SWITCHING FREQUENCY (Hz) 233 232 231 230 229 228 227 226
MAX14514 toc14
EL SWITCHING FREQUENCY vs. TEMPERATURE
260 EL SWITCHING FREQUENCY (Hz) 250 240 230 220 210 200 190 180
MAX14514 toc15
600 EL SWITCHING FREQUENCY (Hz) 500 400 300 200 100 0 0.5 1 1.5 CEL (nF) 2
235
270
225 2.5 2.7 3.4 4.1 4.8 5.5 SUPPLY VOLTAGE (V)
-40
-15
10
35
60
85
TEMPERATURE (C)
6
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Dual Electroluminescent Lamp Driver
Typical Operating Characteristics (continued)
(VDD = +3.6V, TA = +25C, unless otherwise noted.)
MAX14514
BOOST CONVERTER FREQUENCY vs. CSW
MAX14514 toc16
BOOST CONVERTER FREQUENCY vs. SUPPLY VOLTAGE
MAX14514 toc17
BOOST CONVERTER FREQUENCY vs. TEMPERATURE
BOOST CONVERTER FREQUENCY (kHz) 128 126 124 122 120 118 116 114 112 110
MAX14514 toc18
140 BOOST CONVERTER FREQUENCY (Hz) 120 100 80 60 40 20 0 80 130 CSW (pF) 180
130 BOOST CONVERTER FREQUENCY (kHz) 128 126 124 122 120 118 116 114 112 110 2.7 3.4 4.1 4.8
130
5.5
-40
-15
10
35
60
85
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
OUTPUT VOLTAGE SLOPE vs. RSLEW
MAX14514 toc19
OUTPUT VOLTAGE SLOPE vs. SUPPLY VOLTAGE
MAX14514 toc20
OUTPUT VOLTAGE SLOPE vs. TEMPERATURE
OUTPUT VOLTAGE SLOPE (V/100s) 35 34 33 32 31 30 29 28 27 26
MAX14514 toc21
45 OUTPUT VOLTAGE SLOPE (V/100s) 40 35 30 25 20 15 10 5 300 400 500 600 700 800 900
36 OUTPUT VOLTAGE SLOPE (V/100s) 35 34 33 32 31 30 29 28 27 26
36
1000
2.7
3.4
4.1
4.8
5.5
-40
-15
10
35
60
85
RSLEW (k)
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
SLOW TURN-ON/TURN-OFF TIME vs. CCAP
SLOW TURN-ON/TURN-OFF TIME (s) 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 2 4 6 8 10 CCAP (nF) VDD = 5.5V DIM1 = 0V to VDD DIM2 = GND
MAX14514 toc22
NORMALIZED BRIGHTNESS LEVEL vs. SUPPLY VOLTAGE
1.8 NORMALIZED BRIGHTNESS LEVEL 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 2.7 3.4 4.1 SUPPLY VOLTAGE 4.8 5.5
MAX14514 toc23
TYPICAL V_, VCOM, AND V_ - VCOM WAVEFORMS
1
2
MAX14514 toc24
V_ - VCOM 50V/div
V_, VCOM 25V/div 1ms/div
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Dual Electroluminescent Lamp Driver MAX14514
Pin Description
PIN 1 NAME DIM1 FUNCTION High-Voltage Output 1 Dimming Control. Apply a PWM signal, DC analog control signal, or connect a resistor from DIM1 to GND to adjust V1 peak-to-peak output voltage. Drive DIM1 high or leave DIM1 unconnected to set V1 to full brightness level. High-Voltage Output 2 Dimming Control. Apply a PWM signal, DC analog control signal, or connect a resistor from DIM2 to GND to adjust V2 peak-to-peak output voltage. Drive DIM2 high or leave DIM2 unconnected to set V2 to full brightness level. Turn-On Time Input. For fast turn-on mode, connect CAP to VDD. For slow turn-on/-off mode, connect a capacitor from CAP to GND to set the turn-on/-off time. tON/OFF = 0.27 x CCAP x RSLEW. EL Voltage Switching Frequency. Connect an external capacitor, CEL, from EL to GND or drive EL with an external oscillator to set the switching frequency of the V1 and V2 high-voltage outputs. Connect EL to GND to shut off the EL oscillator. Boost Converter Switching Frequency. Connect an external capacitor, CSW, from 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. To avoid LX shorting to GND and causing an increase in internal die temperature, do not keep SW high. The MAX14514 is protected by entering a thermal-shutdown state. (See the Thermal Short-Circuit Protection section.) Input Supply Voltage Ground Internal Switching DMOS Drain Connection. Connect LX to a switching inductor and an anode of a rectifying diode. High-Voltage Feedback Connection. Connect CS to output of boost converter (cathode of rectifying diode). High-Voltage EL Panel Common Output. Connect COM to common side of EL lamp. High-Voltage EL Panel Output 2. Connect V2 to non-COM side of EL lamp 2. High-Voltage EL Panel Output 1. Connect V1 to non-COM side of EL lamp 1. Enable Input. Drive EN > VIH_EN to turn on the device. Drive EN < VIL_EN to turn off the device (see the Shutdown section). High-Voltage Slew-Rate Control. Connect an external resistor, RSLEW, from SLEW to GND to set the slew rate of the high-voltage outputs V1 and V2. Exposed Pad. Connect EP to GND.
2
DIM2
3
CAP
4
EL
5
SW
6 7 8 9 10 11 12 13 14
VDD GND LX CS COM V2 V1 EN SLEW EP
8
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Dual Electroluminescent Lamp Driver
Functional Diagram
MAX14514
VDD LX SW SWITCH OSCILLATOR N
EL
EL OSCILLATOR
REF VSENSE CS
SLEW
V-I CONVERTER HIGH ESD PROTECTION V1
EL
LOW-POWER SHUTDOWN DMOS DRIVER
DIM1 DIM2 CAP
PWM CONVERTER
H-BRIDGE
HIGH ESD PROTECTION
V2
LOW PEAK DETECTOR
HIGH ESD PROTECTION
COM
THERMAL SHUTDOWN
NO-OPERATION SIGNAL
GND
UVLO LOW-POWER SHUTDOWN
MAX14514
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9
Dual Electroluminescent Lamp Driver MAX14514
Detailed Description
The MAX14514 high-voltage DC-AC converter is designed to drive two EL lamps. The MAX14514 features a +2.7V to 5.5V input range that allows the device to accept a wide variety of voltage sources, including single-cell Li+ batteries. The lamp outputs of the device generate up to 300VP-P for maximum lamp brightness. The slew rate, frequency, and peak-to-peak voltage of the MAX14514 EL lamp outputs are programmed through a combination of external components and/or logic inputs. The peak-to-peak EL lamp output voltage is related to VDIM_ (for VDIM_ > VIL_DIM_) or PWM duty cycle by the following equation: V_ - VCOM = 260 x (VDIM_) = 260 x (%duty cycle) x (VIH_DIM_)
Slow Turn-On, Slow Turn-Off
The MAX14514 provides a slow turn-on and slow turnoff time feature that is enabled by connecting a capacitor from CAP to GND (see the Typical Application Circuit and the CCAP Capacitor Selection section). This slow turn-on/-off feature causes the peak-to-peak voltage of the EL outputs to slowly rise or fall any time the outputs are enabled or disabled, either through EN or DIM_ (see Table 1). The slow rise and fall of the peakto-peak EL output voltage creates a soft fade-on and fade-off of the EL lamp, rather than an abrupt change in brightness. To disable the slow turn-on/turn-off feature, connect CAP to VDD.
Output Slew Rate
The MAX14514 uses the resistor RSLEW to set a reference current for the 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.)
Output Frequency
The MAX14514 uses an internal oscillator to set the desired output 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 CEL capacitor value.)
Table 1. Slow Turn-On, Slow Turn-Off
LOGIC INPUT EN 10 01 1 1 1 1 DIM1 1 1 10 01 X X DIM2 1 1 X X 10 01 V1 Slow Turn-Off Slow Turn-On Slow Turn-Off Slow Turn-On X X EL OUTPUTS* V2 Slow Turn-Off Slow Turn-On X X Slow Turn-Off Slow Turn-On
Dimming Control
The MAX14514 features dimming control inputs, DIM1 and DIM2, to control the peak-to-peak voltages on lamp outputs V1, V2, and COM. DIM_ is controlled by either a DC voltage, a PWM signal, or a resistor from DIM_ to GND. (See the RDIM Resistor Selection section.) Applying a DC voltage to DIM_ ranging from VLPD to VIH_DIM_ linearly varies the corresponding output voltage from 130V to 300V. Increasing the voltage on DIM_ increases the peak-to-peak output, and decreasing the voltage on DIM_ decreases the peak-to-peak output voltage. Note that when VDIM_ goes below VIL_DIM_, the corresponding output turns off. DIM_ features an internal lowpass filter to allow a PWM signal to control the output voltage. Voltages on DIM_ are internally level translated down to VIH_DIM_, so that the equivalent voltage on DIM_ is (%duty cycle) x VIH_DIM_. The DIM_ inputs accept the 200kHz to 1MHz frequency range. Note that for PWM signals, the logic voltage applied to DIM__ must be greater than or equal to VIH_DIM_.
*With capacitor from CAP to GND (CAP is not connected to VDD).
X = Don't Care.
Boost Converter
The MAX14514 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 lamps, CLAMP1 and CLAMP2, 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 lamps. Note: Keeping SW high shorts LX to GND and causes the internal die temperature to increase. The MAX14514 is protected by entering a thermal-shutdown state (see the Thermal Short-Circuit Protection section).
10
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Dual Electroluminescent Lamp Driver
The MAX14514 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.) high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, the MAX14514 keeps working without latchup or damage. ESD protection can be tested in various ways. The transmitter EL lamp outputs of the MAX14514 are characterized for protection to the following limits: * 15kV using the Human Body Model * * 4kV IEC 61000-4-2 Contact Discharge 4kV IEC 61000-4-2 Air-Gap Discharge
MAX14514
Shutdown
The MAX14514 features a shutdown mode to disable the device and reduce supply current. Entering and exiting shutdown mode depends on if slow turn-on/turnoff is enabled or disabled. When slow turn-on/turn-off is enabled, shut down the device by driving EN low. Enable the device by driving EN high. When slow turn-on/turn-off is disabled, shut down the device by driving EN low and both DIM1 and DIM2 below VIL_DIM_. Enable the device by driving EN high and either DIM1 or DIM2 above VLPD_.
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 MAX14514 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 61000-4-2 ESD Contact Discharge test. 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.
Undervoltage Lockout (UVLO)
The MAX14514 has a UVLO threshold of +2.1V (typ). When VDD falls below this threshold, the device enters a nonoperative mode.
Thermal Short-Circuit Protection
The MAX14514 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 (typ).
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 MAX14514 (V1, V2, and COM) have extra protection against static electricity. Maxim's engineers have developed state-ofthe-art structures to protect these pins against ESD of 15kV without damage. The ESD structures withstand
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11
Dual Electroluminescent Lamp Driver MAX14514
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
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.
Table 2. Inductor Vendors
INDUCTOR VALUE (H) 220 330 470 220 330 470 220 220 VENDOR TOKO Coilcraft Coilcraft Coilcraft Coilcraft Coilcraft Cooper Bussmann Cooper Bussmann WEBSITE www.tokoam.com www.coilcraft.com www.coilcraft.com www.coilcraft.com www.coilcraft.com www.coilcraft.com www.cooperet.com www.cooperet.com PART D312C 1001BS-221M DO1608C-334ML DO1608C-474ML LPS4018-224ML LPS4018-334ML LPS4018-474ML SDH3812-221-R SD3110-221-R
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Dual Electroluminescent Lamp Driver
RSLEW Resistor Selection To help reduce audible noise emission by the EL lamps, the MAX14514 features a slew-rate control input (SLEW) that allows the user to set the slew rate of high-voltage outputs, V1, V2, and COM, by connecting a resistor, R SLEW , from the SLEW input to GND. Decreasing the value of RSLEW increases the slew rate at the EL lamp output. Increasing the value of RSLEW decreases the slew rate at the EL lamp outputs. The output slew rate is related to RSLEW by the following equation:
SlewRate(V/100s) = 12/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 1.2M to 600k. For example, if the desired slew rate is 20(V/100s), this leads to an RSLEW value of 12/20(V/100s) = 600k. Note: Connecting RSLEW to GND does 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 section), the frequency of the EL lamp (see the CEL Capacitor Selection section), and the peak-to-peak voltage of the EL lamp. larger than 220H, it may be necessary to increase CCS. For a 470H inductor and CLAMP_TOTAL = 20nF, a CCS ranging from 3.3nF to 6.8nF is recommended.
MAX14514
CEL Capacitor Selection The MAX14514 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. The EL lamp output frequency is related to the CEL capacitor by the following equation:
fEL = 0.08175/(RSLEW x CEL) For example, an RSLEW = 375k and a CEL capacitor value of 872pF equals an EL lamp output frequency of fEL = 250Hz.
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 = 3.6/(RSLEW x CSW) 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 MAX14514 is protected by entering a thermal-shutdown state. (See the Thermal Short-Circuit Protection section.)
CCAP Capacitor Selection
The MAX14514 provides a slow turn-on/-off feature that is enabled by connecting a capacitor from CAP to GND. For fast turn-on/-off, connect CAP to VDD. Slow turn-on/-off time is related by the following equation: tON/OFF = 0.27 x CCAP x RSLEW
RDIM Resistor Selection The MAX14514 features dimming control inputs, DIM1 and DIM2, to control the peak-to-peak voltages on the lamp outputs V1, V2, and COM. DIM_ is controlled by a PWM signal, DC voltage, or by a resistor connected from DIM_ to GND. When using a resistor, the output voltage is related by the following equation:
V_ - VCOM = 260 x RDIM/RSLEW
Bypass 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.
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
EL Lamp Selection
EL lamps have a capacitance of approximately 2.5nF to 3.5nF per square inch. The MAX14514 effectively charges capacitance ranging from 2nF to 20nF.
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13
Dual Electroluminescent Lamp Driver MAX14514
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. PROCESS: BiCMOS-DMOS
Chip Information
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 14 TDFN-EP PACKAGE CODE T1433-2 DOCUMENT NO. 21-0137
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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