MAXIM MAX14514

19-4466; Rev 0; 2/09
KIT
ATION
EVALU
E
L
B
A
IL
AVA
Dual Electroluminescent Lamp Driver
♦ 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
Ordering Information
PART
MAX14514ETD+
TEMP RANGE
PIN-PACKAGE
-40°C to +85°C
14 TDFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
CS
LX
TOP VIEW
COM
Pin Configuration
V2
Applications
♦ +2.7V to +5.5V Input Voltage Range
V1
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 TDFN package and is specified over the
extended -40°C to +85°C operating temperature range.
♦ 300VP-P Maximum Output for Highest Brightness
EN
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.
♦ Dual ±15kV ESD-Protected EL Lamp Outputs
SLEW
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 220µH inductor to effectively drive total combined lamp sizes of up to 20nF.
Features
14
13
12
11
10
9
8
Keypad Backlighting
LCD Backlighting
PDAs/Smartphones
MAX14514
Automotive Instrument Clusters
*EP
4
5
6
7
SW
VDD
GND
DIM2
3
EL
2
CAP
1
DIM1
+
TDFN-EP
(3mm x 3mm)
*EP = EXPOSED PAD. CONNECT EP TO GND OR LEAVE UNCONNECTED.
________________________________________________________________ Maxim Integrated Products
For information on other Maxim products, visit Maxim’s website at www.maxim-ic.com.
1
MAX14514
General Description
Dual Electroluminescent Lamp Driver
MAX14514
Typical Application Circuit
RSLEW
BASEBAND/PMIC
DIM1
SLEW
DIM2
EN
CCAP
V1
CAP
MAX14514
CEL
EL
V2
CSW
SW
COM
VDD
CS
GND
LX
EL LAMP
CLAMP = 10nF
EL LAMP
CLAMP = 10nF
VDD
0.1µF
VBAT
CCS = 3.3nF
LX = 220µH
4.7µF
2
_______________________________________________________________________________________
Dual Electroluminescent Lamp Driver
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
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 = 220µH (ISAT = 170mA, RS = 5.5Ω), TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +3.0V, TA = +25°C.) (Note 2)
PARAMETER
Input Supply Voltage
Input Supply Current
SYMBOL
VDD
IIN
Shutdown Supply Current
ISHDN
Shutdown Inductor Supply
Current
ILX_SHDN
Undervoltage Lockout
Undervoltage Lockout Hysteresis
CONDITIONS
VUV
MIN
TYP
2.7
RSLEW = 375kΩ, FEL = 200Hz,
(V1,V2) - VCOM = 300VP-P
EN = GND
TA = +25°C
40
TA = -40°C to +85°C
UNITS
5.5
V
700
µA
150
400
EN = GND, LX = VDD, CS = VDD
VDD falling
MAX
1.5
1.8
VUV_HYST
2.1
2.3
125
nA
µA
V
mV
EL OUTPUTS (V1, V2, COM)
Peak-to-Peak Output Voltage
V_ - VCOM
VDD = +3V
VDIM_ = +0.5V
105
130
VDIM_ = +1V
210
260
162
310
VDIM_ = +1.3V
250
300
350
V
V1, V2 High-Side Switch OnResistance
RONHS_VN
ISOURCE = 1mA
1.5
3.0
kΩ
V1, V2 Low-Side Switch OnResistance
RONLS_VN
ISINK = 1mA
0.7
2.0
kΩ
COM High-Side Switch OnResistance
RONHS_COM ISOURCE = 1mA
0.7
1.5
kΩ
COM Low-Side Switch OnResistance
RONLS_COM ISINK = 1mA
0.4
1.0
kΩ
High-Side Switch Off-Leakage
RONHS_LEAK V1, V2, VCOM = 0, VCS = 150V
-1
+1
µA
Low-Side Switch Off-Leakage
RONLS_LEAK V1, V2, VCOM = 150V, VCS = 150V
-1
+1
µA
290
Hz
EL Lamp Switching Frequency
ESD Protection (COM, V1, V2
Only)
fEL
CEL = 872pF, RSLEW = 375kΩ
210
250
Human Body Model
±15
IEC 61000-4-2 Contact Discharge
±4
IEC 61000-4-2 Air-Gap Discharge
±4
kV
_______________________________________________________________________________________
3
MAX14514
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 = +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
MAX14514
Dual Electroluminescent Lamp Driver
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +5.5V, CLAMP_TOTAL = 10nF, CCS = 3.3nF, LX = 220µH (ISAT = 170mA, RS = 5.5Ω), TA = -40°C to +85°C, unless
otherwise noted. Typical values are at VDD = +3.0V, TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
BOOST CONVERTER
Output Regulation Voltage
VCS
VDD = +3V
VDIM_ = +0.5V
52
65
81
VDIM_ = +1V
105
130
155
VDIM_ = +1.3V
125
150
175
80
100
120
Boost Switching Frequency
fSW
CSW = 96pF, RSLEW = 375kΩ
Switch On-Resistance
RLX
ISINK = 25mA, VDD = +3V
LX Leakage Current
ILX
VLX = +150V
CS Input Current
ICS
No load, VCS = +150V, VEN = 0, VDIM_ = 0
-1
V
kHz
20
Ω
+1
µA
50
µA
CONTROL INPUT (SW)
Input-Voltage High Threshold
VIH_CSW
RSLEW = 375kΩ
0.9
0.98
1.06
V
Input-Voltage Low Threshold
VIL_CSW
RSLEW = 375kΩ
0.43
0.49
0.55
V
Input Low Current
IIL_CSW
RSLEW = 375kΩ, VCS = +78V, CEL = VDD,
VDIM_ = VDD
43
79
µA
Input High Current
IIH_CSW
RSLEW = 375kΩ, VCS = +78V, CEL = VDD,
VDIM_ = VDD
5
7.5
µA
Input-Voltage High Threshold
VIH_CEL
RSLEW = 375kΩ
1.08
1.32
V
Input-Voltage Low Threshold
VIL_CEL
RSLEW = 375kΩ
0.22
0.39
V
Input Low Current
IIL_CEL
RSLEW = 375kΩ
1.3
1.88
µA
Input High Current
IIH_CEL
RSLEW = 375kΩ
1.3
1.88
µA
fCAP
RSLEW = 375kΩ, CCAP = 1.25nF
180
410
Hz
Slow Turn-On Time
tSLOW_ON
RSLEW = 375kΩ, CCAP = 1.25nF
Fast Turn-On CAP Threshold
VFAST_CAP RSLEW = 375kΩ
CONTROL INPUT (EL)
CONTROL INPUT (CAP)
CAP Switching Frequency
Nonfast Turn-On CAP Threshold
Input Leakage Current
VNONFAST_CAP
300
0.3
V
RSLEW = 375kΩ
IIH_CAP
CAP = VDD, RSLEW =
375kΩ
VFORCE
RSLEW = 375kΩ
s
VDD - 0.35
1.4
V
Normal operation
0.3
1
µA
Shutdown mode
-100
100
nA
CONTROL INPUT (SLEW)
Force Voltage
High-Voltage Output Slew Rate
0.9
RSLEW = 375kΩ
0.98
1.05
32
V
V/100µs
CONTROL INPUTS (DIM1, DIM2)
Input High Voltage
VIH_DIM__
Max output voltage
Input Low Voltage
VIL_DIM__
Min output voltage
1.3
Input Low Current
IIL_DIM__
VDIM_ = 0, RSLEW = 375kΩ
2.2
Input High Current
IIH_DIM__
VDIM_ = VDD
-1
PWM Frequency Range
2.6
V
3.0
µA
+1
0.2 to 1
Low-Peak Detector Threshold
VLPD
Low-Peak Detector Hysteresis
VLPD_HYST
4
V
0.15
0.13
0.35
100
_______________________________________________________________________________________
µA
MHz
V
mV
Dual Electroluminescent Lamp Driver
(VDD = +2.7V to +5.5V, CLAMP_TOTAL = 10nF, CCS = 3.3nF, LX = 220µH (ISAT = 170mA, RS = 5.5Ω), TA = -40°C to +85°C, unless
otherwise noted. Typical values are at VDD = +3.0V, TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
0.3
V
CONTROL INPUT (EN)
Input Logic-High Voltage
VIH_EN
Input Logic-Low Voltage
VIL_EN
1.4
V
THERMAL SHUTDOWN
Thermal Shutdown
Thermal Shutdown Hysteresis
158
°C
8
°C
MAX14514
ELECTRICAL CHARACTERISTICS (continued)
Note 2: All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
Typical Operating Characteristics
(VDD = +3.6V, TA = +25°C, unless otherwise noted.)
5
10
5
0
0
3.4
4.1
4.8
5.5
225
40
150
20
75
-15
10
35
60
85
0
40
80
120
160
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
BOOST CONVERTER FREQUENCY (kHz)
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
SHUTDOWN CURRENT
vs. TEMPERATURE
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
0.35
0.3
0.25
0.2
0.15
0.1
100
DIM1 = DIM2 = EN = 0V
10
1
0.1
0.01
0.05
3.4
4.1
SUPPLY VOLTAGE (V)
4.8
5.5
DIM = 1V
200
150
DIM_ = 0.7V
100
DIM_ = 0.4V
DIM = 0.5V
50
0
0.001
0
200
250
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
DIM1 = DIM2 = EN = 0V
MAX14514 toc05
MAX14514 toc04
0.4
2.7
60
0
-40
SHUTDOWN CURRENT (nA)
2.7
SHUTDOWN CURRENT (nA)
15
300
PEAK-TO-PEAK OUTPUT
90% DUTY CYCLE
MAX14514 toc06
10
20
MAX14514 toc03
80
TOTAL INPUT CURRENT (mA)
15
INPUT CURRENT AND PEAK-TO-PEAK OUTPUT
VOLTAGE vs. BOOST CONVERTER FREQUENCY
MAX14514 toc02
20
25
TOTAL INPUT CURRENT (mA)
MAX14514 toc01
TOTAL INPUT CURRENT (mA)
25
TOTAL INPUT CURRENT
vs. TEMPERATURE
-40
-15
10
35
TEMPERATURE (°C)
60
85
2.7
3.4
4.1
4.8
5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
TOTAL INPUT CURRENT
vs. SUPPLY VOLTAGE
Typical Operating Characteristics (continued)
(VDD = +3.6V, TA = +25°C, unless otherwise noted.)
150
100
50
200
VDD = 4.6V
150
VDD = 3.6V
100
VDD = 2.7V
50
-15
10
35
60
0.35
85
50
0.85
20
1.35
40
60
80
RMS OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
AVERAGE OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
AVERAGE OUTPUT VOLTAGE
vs. TEMPERATURE
50
40
30
20
500
400
300
200
4.1
4.8
2.7
5.5
500
400
300
200
0
0
3.4
600
100
100
0
MAX14514 toc12
600
700
AVERAGE OUTPUT VOLTAGE (mV)
60
MAX14514 toc11
MAX14514 toc10
70
700
10
3.4
4.1
4.8
-40
5.5
-15
10
35
60
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
EL SWITCHING FREQUENCY vs. CEL
EL SWITCHING FREQUENCY
vs. SUPPLY VOLTAGE
EL SWITCHING FREQUENCY
vs. TEMPERATURE
300
200
100
233
232
231
230
229
228
227
225
1
1.5
CEL (nF)
2
2.5
260
250
240
230
220
210
200
190
226
0
270
85
MAX14514 toc15
234
EL SWITCHING FREQUENCY (Hz)
400
MAX14514 toc14
500
235
EL SWITCHING FREQUENCY (Hz)
MAX14514 toc13
600
6
100
DUTY CYCLE (%)
80
0.5
fDIM = 200kHz
150
DIM VOLTAGE (V)
90
2.7
fDIM = 1MHz
200
TEMPERATURE (°C)
AVERAGE OUTPUT VOLTAGE (mV)
-40
DIM1 = DIM2
VDD = 5.5V
0
0
0
RMS OUTPUT VOLTAGE (V)
VDD = 5.5V
250
MAX14514 toc09
DIM1 = DIM2
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
200
250
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
MAX14514 toc07
PEAK-TO-PEAK OUTPUT VOLTAGE (V)
250
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. DIM DUTY CYCLE
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. DIM VOLTAGE
MAX14514 toc08
PEAK-TO-PEAK OUTPUT VOLTAGE
vs. TEMPERATURE
EL SWITCHING FREQUENCY (Hz)
MAX14514
Dual Electroluminescent Lamp Driver
180
2.7
3.4
4.1
4.8
SUPPLY VOLTAGE (V)
5.5
-40
-15
10
35
TEMPERATURE (°C)
_______________________________________________________________________________________
60
85
Dual Electroluminescent Lamp Driver
BOOST CONVERTER FREQUENCY
vs. SUPPLY VOLTAGE
100
80
60
40
20
124
122
120
118
116
114
130
126
124
122
120
118
116
114
110
3.4
4.1
4.8
5.5
-40
-15
10
35
60
CSW (pF)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
OUTPUT VOLTAGE SLOPE vs. RSLEW
OUTPUT VOLTAGE SLOPE
vs. SUPPLY VOLTAGE
OUTPUT VOLTAGE SLOPE
vs. TEMPERATURE
30
25
20
15
34
33
32
31
30
29
28
10
27
5
26
400
500
600
700
800
900
1000
MAX14514 toc21
35
35
34
33
32
31
30
29
28
27
26
2.7
3.4
4.1
4.8
5.5
-40
-15
10
35
60
RSLEW (kΩ)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SLOW TURN-ON/TURN-OFF TIME vs. CCAP
NORMALIZED BRIGHTNESS LEVEL
vs. SUPPLY VOLTAGE
TYPICAL V_, VCOM, AND
V_ - VCOM WAVEFORMS
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
MAX14514 toc24
2
1.8
1.6
V_ - VCOM
50V/div
1.4
1.2
1
0.8
0.6
0.4
V_, VCOM
25V/div
0.2
0.1
85
MAX14514 toc23
VDD = 5.5V
DIM1 = 0V to VDD
DIM2 = GND
NORMALIZED BRIGHTNESS LEVEL
MAX14514 toc22
1
85
36
OUTPUT VOLTAGE SLOPE (V/100μs)
35
MAX14514 toc20
40
36
OUTPUT VOLTAGE SLOPE (V/100μs)
MAX14514 toc19
45
300
128
112
2.7
180
MAX14514 toc18
126
130
110
80
OUTPUT VOLTAGE SLOPE (V/100μs)
128
112
0
SLOW TURN-ON/TURN-OFF TIME (s)
MAX14514 toc17
120
130
BOOST CONVERTER FREQUENCY (kHz)
MAX14514 toc16
BOOST CONVERTER FREQUENCY (Hz)
140
BOOST CONVERTER FREQUENCY
vs. TEMPERATURE
BOOST CONVERTER FREQUENCY (kHz)
BOOST CONVERTER FREQUENCY vs. CSW
0
0
0
2
4
6
CCAP (nF)
8
10
MAX14514
Typical Operating Characteristics (continued)
(VDD = +3.6V, TA = +25°C, unless otherwise noted.)
2.7
3.4
4.1
4.8
5.5
1ms/div
SUPPLY VOLTAGE
_______________________________________________________________________________________
7
Dual Electroluminescent Lamp Driver
MAX14514
Pin Description
PIN
NAME
1
DIM1
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.
2
DIM2
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.
3
CAP
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.
4
EL
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.
SW
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.)
6
VDD
Input Supply Voltage
7
GND
Ground
8
LX
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).
5
8
FUNCTION
9
CS
10
COM
11
V2
High-Voltage EL Panel Output 2. Connect V2 to non-COM side of EL lamp 2.
12
V1
High-Voltage EL Panel Output 1. Connect V1 to non-COM side of EL lamp 1.
13
EN
Enable Input. Drive EN > VIH_EN to turn on the device. Drive EN < VIL_EN to turn off the device (see the
Shutdown section).
14
SLEW
⎯
EP
High-Voltage EL Panel Common Output. Connect COM to common side of EL lamp.
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.
_______________________________________________________________________________________
Dual Electroluminescent Lamp Driver
VDD
LX
SW
EL
SWITCH
OSCILLATOR
EL
OSCILLATOR
N
REF
VSENSE
SLEW
V-I
CONVERTER
EL
LOW-POWER
SHUTDOWN
DIM1
DIM2
DMOS
DRIVER
PWM
CONVERTER
CAP
LOW PEAK
DETECTOR
THERMAL
SHUTDOWN
GND
H-BRIDGE
CS
HIGH ESD
PROTECTION
V1
HIGH ESD
PROTECTION
V2
HIGH ESD
PROTECTION
COM
NO-OPERATION
SIGNAL
UVLO
MAX14514
LOW-POWER
SHUTDOWN
_______________________________________________________________________________________
9
MAX14514
Functional Diagram
MAX14514
Dual Electroluminescent Lamp Driver
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.
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.)
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.
Table 1. Slow Turn-On, Slow Turn-Off
LOGIC INPUT
EL OUTPUTS*
EN
DIM1
DIM2
V1
V2
1≥0
1
1
Slow Turn-Off
Slow Turn-Off
Slow Turn-On
0≥1
1
1
Slow Turn-On
1
1≥0
X
Slow Turn-Off
X
1
0≥1
X
Slow Turn-On
X
Dimming Control
1
X
1≥0
X
Slow Turn-Off
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.)
1
X
0≥1
X
Slow Turn-On
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_.
10
*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).
______________________________________________________________________________________
Dual Electroluminescent Lamp Driver
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_.
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 +158°C (typ). The device turns back on when
the internal die temperature cools to +150°C (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
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
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
1.5kΩ 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.
______________________________________________________________________________________
11
MAX14514
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.)
MAX14514
Dual Electroluminescent Lamp Driver
RC
1MΩ
CHARGE-CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
Cs
100pF
RD
1500Ω
RC
50MΩ TO 100MΩ
DISCHARGE
RESISTANCE
CHARGE-CURRENTLIMIT RESISTOR
DEVICE
UNDER
TEST
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
STORAGE
CAPACITOR
I
100%
90%
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
IPEAK
Ir
Cs
150pF
DISCHARGE
RESISTANCE
Figure 1c. IEC 61000-4-2 ESD Test Model
Figure 1a. Human Body ESD Test Model
IP 100%
90%
HIGHVOLTAGE
DC
SOURCE
RD
330Ω
AMPS
36.8%
10%
0
10%
0
tRL
TIME
tr = 0.7ns TO 1ns
tDL
CURRENT WAVEFORM
t
30ns
60ns
Figure 1d. IEC 61000-4-2 ESD Generator Current Waveform
Figure 1b. Human Body Current Waveform
Design Procedure
LX Inductor Selection
The recommended inductor values are 220µH/330µH.
For most applications, series resistance (DCR) should
be below 8Ω for reasonable efficiency. Do not exceed
the inductor’s saturation current.
Table 2. Inductor Vendors
12
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
______________________________________________________________________________________
Dual Electroluminescent Lamp Driver
larger than 220µH, it may be necessary to increase
CCS. For a 470µH inductor and CLAMP_TOTAL = 20nF, a
CCS ranging from 3.3nF to 6.8nF is recommended.
SlewRate(V/100µs) = 12/RSLEW(MΩ)
fEL = 0.08175/(RSLEW x CEL)
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 1.2MΩ to 600kΩ. For example, if the
desired slew rate is 20(V/100µs), this leads to an RSLEW
value of 12/20(V/100µs) = 600kΩ.
Note: Connecting RSLEW to GND does not damage the
device. However, for the device to operate correctly,
RSLEW should be in the 100kΩ to 2.2MΩ 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.
For example, an RSLEW = 375kΩ and a CEL capacitor
value of 872pF equals an EL lamp output frequency of
fEL = 250Hz.
CCAP Capacitor Selection
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.)
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
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:
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)
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:
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.
V_ - VCOM = 260 x RDIM/RSLEW
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 lamps have a capacitance of approximately 2.5nF to
3.5nF per square inch. The MAX14514 effectively
charges capacitance ranging from 2nF to 20nF.
Bypass Capacitor Selection
Diode Selection
EL Lamp Selection
______________________________________________________________________________________
13
MAX14514
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:
MAX14514
Dual Electroluminescent Lamp Driver
Applications Information
PCB Layout
Chip Information
PROCESS: BiCMOS-DMOS
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.
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
14 TDFN-EP
T1433-2
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.
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