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 300V P-P for maximum lamp brightness.
The MAX14514 utilizes an inductor-based boost con-verter to generate the high voltage necessary to drive EL lamps and allows the use of a 220μH inductor to effec-tively 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 slew-rate of the rising and falling edges of the AC drive waveform to reduce audible noise output. The high-volt-age 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 +158°C (typ).
The MAX14514 is available in a space-saving, 14-pin,3mm x 3mm TDF N package and is specified over the extended -40°C to +85°C operating temperature range.
Applications
Keypad Backlighting LCD Backlighting PDAs/Smartphones
Automotive Instrument Clusters
Features
?Dual ±15kV ESD-Protected EL Lamp Outputs ?300V P-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
________________________________________________________________Maxim Integrated Products
1
Pin Configuration
Ordering Information
+Denotes a lead(Pb)-free/RoHS-compliant package.*EP = Exposed pad.
For information on other Maxim products, visit Maxim’s website at https://www.doczj.com/doc/e617405076.html,.
M A X 14514
Dual Electroluminescent Lamp Driver 2_______________________________________________________________________________________
Typical Application Circuit
MAX14514
Dual Electroluminescent Lamp Driver
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V = +2.7V to +5.5V, C = 10nF, C = 3.3nF, L = 220μH (I = 170mA, R = 5.5Ω), T = -40°C to +85°C, unless oth-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.
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 https://www.doczj.com/doc/e617405076.html,/thermal-tutorial .
(Voltages referenced to GND.)
V DD ........................................................................-0.3V to +6.0V CS, LX...................................................................-0.3V to +160V V 1, V 2, COM................................................-0.3V to (V CS + 0.3V)SW, EL, DIM_, SLEW, CAP, EN..................-0.3V to (V DD + 0.3V)Continuous Power Dissipation (T A = +70°C)
14-Pin TDFN (derate 24.4mW/°C above +70°C).......1951mW Junction-to-Case Thermal Resistance (θJC ) (Note 1)
14-Pin TDFN...................................................................8°C/W
Junction-to-Ambient Thermal Resistance (θJA ) (Note 1)
14-Pin TDFN.................................................................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
M A X 14514
Dual Electroluminescent Lamp Driver
ELECTRICAL CHARACTERISTICS (continued)
MAX14514
Dual Electroluminescent Lamp Driver
_______________________________________________________________________________________5
TOTAL INPUT CURRENT vs. SUPPLY VOLTAGE
M A X 14514 t o c 01
SUPPLY VOLTAGE (V)
T O T A L I N P U T C U R R E N T (m A )
3.4
4.1
4.8
51015
202502.7
5.5
TOTAL INPUT CURRENT vs. TEMPERATURE
M A X 14514 t o c 02
TEMPERATURE (°C)
T O T A L I N P U T C U R R E N T (m A )
35
60
-15
10
5
10
15
20
250-40
85
INPUT CURRENT AND PEAK-TO-PEAK OUTPUT VOLTAGE vs. BOOST CONVERTER FREQUENCY
BOOST CONVERTER FREQUENCY (kHz)
T O T A L I N P U T C U R R E N T (m A )
P E A K -T O -P E A K O U T P U T V O L T A G E (V
)
80
120
160
204060
80
075
150
225
300
40
200
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
S H U T D O W N C U R R E N T
(n A )
3.4
4.1
4.8
0.10.20.250.350.050.150.30.4
02.7
5.5
SHUTDOWN CURRENT vs. TEMPERATURE
TEMPERATURE (°C)
S H U T D O W N C U R R E N T (n A )
35
60
-15
10
0.110
0.01
1100
0.001
-40
85
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
P E A K -T O -P E A K O U T P U T V O L T A G E (V )
3.4
4.1
4.8
100
200
50
150250
02.7
5.5
Typical Operating Characteristics
(V DD = +3.6V, T A = +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (continued)
(V DD = +2.7V to +5.5V, C LAMP_TOTAL = 10nF, C CS = 3.3nF, L X = 220μH (I SAT = 170mA, R S = 5.5
Ω), T A = -40°C to +85°C, unless otherwise noted. Typical values are at V DD = +3.0V, T A = +25°C.) (Note 2)
M A X 14514
Dual Electroluminescent Lamp Driver 6_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V DD = +3.6V, T A = +25°C, unless otherwise noted.)
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. TEMPERATURE
M A X 14514 t o c 07
TEMPERATURE (°C)
P E A K -T O -P E A K O U T P U T V O L T A G E (V )
35
60
-15
10
50100150200
2500-40
85
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. DIM VOLTAGE
DIM VOLTAGE (V)
P E A K -T O -P E A K O U T P U T V O L T A G E (V )
1.35
100
200
50150
25000.35
0.85PEAK-TO-PEAK OUTPUT VOLTAGE
vs. DIM DUTY CYCLE
DUTY CYCLE (%)
P E A K -T O -P E A K O U T P U T V O L T A G E (V )
60
40
100
200
50
150
250
020
80
RMS OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
M A X 14514 t o c 10
SUPPLY VOLTAGE (V)R M S O U T P U T V O L T A G E (V )
3.4
4.1
4.8
10305070204060809002.7
5.5AVERAGE OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
M A X 14514 t o c 11
SUPPLY VOLTAGE (V)A V E R A G E O U T P U T V O L T A G E (m V )
3.4
4.1 4.81003005002004006007000
2.7 5.5AVERAGE OUTPUT VOLTAGE
vs. TEMPERATURE
M A X 14514 t o c 12
TEMPERATURE (°C)
A V E R A G E O U T P U T V O L T A G E (m V )
3560-15101003005002004006007000
-4085
EL SWITCHING FREQUENCY vs. C EL
M A X 14514 t o c 13
C EL (nF)
E L S W I T C H I N G
F R E Q U E N C Y (H z )
1
1.52
10030050020040060000.5
2.5
EL SWITCHING FREQUENCY vs. SUPPLY VOLTAGE
M A X 14514 t o c 14
SUPPLY VOLTAGE (V)E L S W I T C H I N G F R E Q U E N C Y (H z )
3.4
4.1 4.8226228230227229231233232234235225
2.7 5.5EL SWITCHING FREQUENCY
vs. TEMPERATURE
M A X 14514 t o c 15
TEMPERATURE (°C)
E L S W I T C H I N G
F R E Q U E N C Y (H z )
35-156010190210230200220240260250270
180
-4085
MAX14514
Dual Electroluminescent Lamp Driver
_______________________________________________________________________________________7
BOOST CONVERTER FREQUENCY vs. C SW
M A X 14514 t o c 16
C SW (pF)
B O O S T
C O N V E R T E R F R E Q U E N C Y (H z )
130
180
20601004080120140080
BOOST CONVERTER FREQUENCY
vs. SUPPLY VOLTAGE
M A X 14514 t o c 17
SUPPLY VOLTAGE (V)B O O S T C O N V E R T E R F R E Q U E N C Y (k H z )
3.4
4.1
4.8
112116120122126114118124128130110
2.7
5.5
BOOST CONVERTER FREQUENCY
vs. TEMPERATURE
M A X 14514 t o c 18
TEMPERATURE (°C)
B O O S T
C O N V E R T E R F R E Q U E N C Y (k H z )
35
60
-15
10
112116120122126114118124128130
110
-40
85
OUTPUT VOLTAGE SLOPE vs. R SLEW
M A X 14514 t o c 19
R SLEW (k Ω)O U T P U T V O L T A G E S L O P E (V /100μs )
500
700
400
800
900
600
10202530401535455300
1000OUTPUT VOLTAGE SLOPE vs. SUPPLY VOLTAGE
M A X 14514 t o c 20
SUPPLY VOLTAGE (V)O U T P U T V O L T A G E S L O P E (V /100μs )
3.4
4.1 4.8283032343626
29313335272.7 5.5OUTPUT VOLTAGE SLOPE vs. TEMPERATURE
M A X 14514 t o c 21
TEMPERATURE (°C)
O U T P U T V O L T A G E S L O P E (V /100μs )
3560-15102830323436
26
2931333527-4085
SLOW TURN-ON/TURN-OFF TIME vs. C CAP
C CAP (nF)
S L O W T U R N -O N /T U R N -O F F T I M E (s )
6
8
2
4
0.20.40.60.81
00.30.50.70.90.10
10
NORMALIZED BRIGHTNESS LEVEL
vs. SUPPLY VOLTAGE
M A X 14514 t o c 23
SUPPLY VOLTAGE
N O R M A L I Z E D B R I G H T N E S S L E V E L
3.4
4.1 4.8
0.40.81.21.62
00.611.41.80.22.7
5.5
TYPICAL V_, V COM , AND V_ - V COM WAVEFORMS
MAX14514 toc24
V_ - V COM 50V/div
V_, V COM 25V/div
1ms/div
Typical Operating Characteristics (continued)
(V DD = +3.6V, T A = +25°C, unless otherwise noted.)
M A X 14514
Dual Electroluminescent Lamp Driver 8_______________________________________________________________________________________
MAX14514
Dual Electroluminescent Lamp Driver
_______________________________________________________________________________________9
Functional Diagram
M A X 14514
Detailed Description
The MAX14514 high-voltage DC-AC converter is designed to drive two EL lamps. The MAX14514 fea-tures 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 300V P-P for maximum lamp brightness. The slew rate, frequency, and peak-to-peak voltage of the MAX14514 EL lamp outputs are pro-grammed through a combination of external compo-nents and/or logic inputs.
Output Slew Rate
The MAX14514 uses the resistor R SLEW to set a refer-ence current for the internal circuitry. The reference current directly affects the slew rate of the EL lamp out-put. Increasing the value of R SLEW decreases the slew rate, and decreasing the value of R SLEW increases the slew rate. (See the R SLEW Resistor Selection section on how to select R SLEW .)
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 C EL Capacitor Selection sec-tion for choosing the C EL capacitor value.)
Dimming Control
The MAX14514 features dimming control inputs, DIM1and DIM2, to control the peak-to-peak voltages on lamp outputs V 1, V 2, and COM. DIM_ is controlled by either a DC voltage, a PWM signal, or a resistor from DIM_ to GND. (See the R DIM Resistor Selection section.)
Applying a DC voltage to DIM_ ranging from V LPD to V IH_DIM_linearly varies the corresponding output volt-age 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 V DIM_goes below V IL_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 V IH_DIM_, so that the equivalent voltage on DIM_ is (%duty cycle) x V IH_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 V IH_DIM_.
The peak-to-peak EL lamp output voltage is related to V DIM_ (for V DIM_> V IL_DIM_) or PWM duty cycle by the following equation:
V_ - V COM = 260 x (V DIM_) = 260 x (%duty cycle) x
(V IH_DIM_)
Slow Turn-On, Slow Turn-Off
The MAX14514 provides a slow turn-on and slow turn-off time feature that is enabled by connecting a capaci-tor from CAP to GND (see the Typical Application Circuit and the C CAP Capacitor Selection section). This slow turn-on/-off feature causes the peak-to-peak volt-age 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 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. To disable the slow turn-on/turn-off feature,connect CAP to V DD .
Boost Converter
The MAX14514 boost converter consists of an external inductor from V DD 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, C LAMP1and C LAMP2, 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 C CS and the EL lamps.
Note: Keeping SW high shorts LX to GND and causes the internal die temperature to increase. The MAX14514is protected by entering a thermal-shutdown state (see the Thermal Short-Circuit Protection section).
Dual Electroluminescent Lamp Driver 10______________________________________________________________________________________
X = Don’t Care.
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MAX14514ETD+T