1
General Description:
The Durel
D356B is part of a family of highly integrated EL
drivers based on Durel's patented three-port (3P) topology, which
offers built-in EMI shielding. This high efficiency device is well
suited for backlighting most timepieces and liquid crystal displays
for portable electronic applications.
Data Sheet
D356B
Electroluminescent
Lamp Driver IC
MSOP-8
High Efficiency
Watches
Low Voltage Operation
Data Organizers/PDAs
Small System Footprint
Pagers
Controlled Current Discharge for Low EMI
LCD and Keypad Backlighting
Capacitor or External Clock LF Control
Features
Applications
Standard Test Circuit
nA
E = GND
mA
E = 3.0V
uA
E = 3.0V
Vpp
H z
CLF=5.0 nF
kHz
Parameter
Symbol
Minimum
Typical
Maximum
Unit
Conditions
(Using Standard Test Circuit at Ta=25 C unless otherwise specified.)
Lamp Driver Specifications:
Standby Current
10
100
Supply Current
I
23
30
Enable Current
50
75
Output Voltage
Vout
110
135
220
Lamp Frequency
LF
230
310
390
Inductor Frequency
HF
23
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
Load B
5.0nF
D356B
3.0 Vdc
0.1
m
H
1.8mH
(3 Ohms)
OFF
ON
GND
3.0V
D356B
2
Supply voltage
Operating Range
V+
1.0
7.0
V
E = V+
Withstand Range
-0.510.0
E = GND
Enable Voltage
E
-0.5 (V+) +0.5V
Output Voltage
Vout
220
Vpp
Peak-to-peak voltage
CLF Voltage
VCLF
0
(V+) +0.3
V
External clock input
Operating Temperature
T
a
-40
85C
Storage Temperature
T
s
-6515
0
C
Typical Output Waveform
Load B*
Physical Data:
PIN # NAME
FUNCTION
Absolute Maximum Ratings:
* Load B approximates a 5in
2
EL lamp.
Note: The above are stress ratings only. Functional operation of the device at these ratings or any other above
those indicated in the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods of time may affect reliability.
Parameter
Symbol
Minimum
Maximum
Unit
Comments
1
GND
System ground connection
2
L-
Negative input to inductor
3
VOUT
High voltage AC output to lamp
4
L+
Positive input to inductor
5
V+
DC power supply input
6
CLF1
Lamp frequency capacitor/clock input
7
CLF2
Lamp frequency capacitor/clock input
8
E
System enable
Note: Please consult factory for bare die dimensions and bond
pad locations.
100W
22 nF
10kW
47 nF
1
2
3
4
5
6
7
8
3
Typical Performance Characteristics Using Standard Test Circuit
Output Frequency vs. DC Supply
Voltage
0
50
100
150
200
250
300
350
400
450
1
2
3
4
5
6
7
DC Input Voltage
LF (Hz)
Output Frequency vs. Ambient
Temperature
0
50
100
150
200
250
300
350
400
450
-40
-20
0
20
40
60
80
Temperature ( C)
LF (Hz)
Output Voltage vs. DC Supply Voltage
0
40
80
120
160
200
240
1
2
3
4
5
6
7
DC Input Voltage
Output Voltage (Vpp)
Output Voltage vs. Ambient
Temperature
0
40
80
120
160
200
240
-40 -20
0
20
40
60
80
Temperature ( C)
Output Voltage (Vpp)
Supply Current vs. DC Supply Voltage
0
10
20
30
40
50
1
2
3
4
5
6
7
DC Input Voltage
Avg Supply Current (mA)
Supply Current vs. Ambient
Temperature
0
10
20
30
40
50
-40
-20
0
20
40
60
80
Temperature ( C)
Avg Supply Current (mA)
4
Theory of Operation
Electroluminescent (EL) lamps are essentially capacitors with one transparent electrode and a special phosphor material
in the dielectric. When a strong AC voltage is applied across the EL lamp electrodes, the phosphor glows. The
required AC voltage is typically not present in most systems and must be generated from a low voltage DC source.
Thus, Durel developed its patented Three-Port (3P) switch-mode inverter circuit to convert the available DC supply
to an optimal drive signal for high brightness and low-noise EL lamp applications. The Durel 3P topology offers the
simplicity of a single DC input, single AC output, and a shared common ground that provides an integrated EMI
shielding.
The D356B drives the EL lamp by repeatedly pumping charge through an external inductor with current from a DC
source and discharging into the capacitance of the EL lamp load. With each high frequency (HF) cycle the voltage on
the lamp is increased. At a period specified by the lamp frequency (LF) oscillator, the voltage on the lamp is discharged
to ground and the polarity of the inductive charging is reversed. By this means, an alternating positive and negative
voltage is developed at the single output lead of the device to one of the electrodes of the EL lamp. The other lamp
electrode is commonly connected to a ground plane, which can then be considered as electrical shielding for any
underlying circuitry on the application.
The EL driving system is divided into several parts: on-chip logic and control, on-chip high voltage output circuitry,
discharge logic circuitry, and off-chip components. The on-chip logic controls the output frequency (LF), as well as the
inductor switching frequency (HF), and HF and LF duty cycles. These signals are combined and buffered to regulate
the high voltage output circuitry. The output circuitry handles the power through the inductor and delivers the high
voltage to the lamp. The selection of off-chip components provides a degree of flexibility to accommodate various lamp
sizes, system voltages, and brightness levels. Since a key objective for EL driver systems is to save space and cost,
required off-chip components were kept to a minimum.
Durel provides a D356B Designer's Kit, which includes a printed circuit evaluation board intended to aid you in
developing an EL lamp driver configuration using the D356B that meets your requirements. A section on designing
with the D356B is included in this datasheet to serve as a guide to help you select the appropriate external components
to complete your D356B EL driver system.
Typical D356B configurations for driving EL lamps in various applications are shown on the following page. The
expected system outputs, such as lamp luminance, lamp output frequency and voltage and average supply current
draw, for the various sample configurations are also shown with each respective figure.
Block Diagram of the Driver Circuitry
High
Frequency
Oscillator
Low
Frequency
Oscillator
EL Lamp
CLF1
CLF2
E
V+
L+
L-
GND
VOUT
F
1.0
m
5
Typical D356B EL Driver Configurations
1.5V Analog Watch
Typical Output
Luminance= 3.5 fL (12 cd/m
2
)
Lamp Frequency = 220 Hz
Supply Current = 19 mA
Vout = 190 Vpp
Load = 1 in
2
Durel3 Green EL
5.0 V PDA
Typical Output
Luminance = 7.7 fL (26.4 cd/m
2
)
Lamp Frequency = 330 Hz
Supply Current = 25 mA
Vout = 200 Vpp
Load = 4 in
2
Durel Green EL
3.0 V Handset LCD or Digital Watch
Typical Output
Luminance = 8.6 fL (29.5 cd/m
2
)
Lamp Frequency = 360 Hz
Supply Current = 12 mA
Vout = 218 Vpp
Load = 1 in
2
Durel3 Green EL
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
1 in
2
EL Lamp
1.0 mH
Murata
LQS33C-102
1.5 V
6.8 nF
D356
1.0
m
F
OFF
ON
GND
1.5V
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
1 in
2
EL Lamp
3.9 mH
Sumida
CLS62-392
3.0 V
4.7 nF
D356
1.0
m
F
OFF
ON
GND
3.0V
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
4 in
2
EL Lamp
3.3 mH
Bujeon
BDS-4020SBL
5.0 V
4.7 nF
D356
1.0
m
F
OFF
ON
GND
5.0V
6
Designing With D356B
I. Lamp Frequency Capacitor (CLF) Selection
Selecting the appropriate value of capacitor for the low frequency oscillator (CLF) will set the output frequency of the
D356 inverter. Figure 1 graphically represents the inversely proportional relationship between the CLF capacitor
value and the oscillator frequency. In this example at V+ = 3.0V, LF=1600 nF-Hz/CLF.
Alternatively, the lamp frequency may also be controlled with an external clock signal with a 50% duty cycle. The
output lamp frequency will be the same frequency as the input clock signal. For example, if a 250Hz input clock signal
is used, the resulting lamp frequency will be 250Hz. The clock signal input voltage should not exceed V+.
The selection of the CLF value can also affect the brightness of the EL lamp because of its control of the lamp frequency
(LF). Although input voltage and lamp size can change EL lamp frequency as well, LF mainly depends on the CLF
value selected or the frequency of the input clock signal to CLF. The luminance of various sizes of
Durel 3 Blue-green
EL lamp driven by a D356B at V+ = 3.0V using the same inductor value is shown in Figure 2 with respect to lamp
frequency.
Figure 1: Typical Lamp Frequency vs. CLF Capacitor
Figure 2: Typical Lamp Luminance vs. Lamp Frequency
0
100
200
300
400
500
600
700
800
900
0
1
2
3
4
5
6
7
8
9
10
CLF (nF)
Lamp Frequency (Hz)
0
1
2
3
4
5
6
7
8
0
200
400
600
800
1000
Lamp Frequency (Hz)
Lamp Luminane (fL)
2in
2
EL Lamp
4in
2
EL Lamp
6in
2
EL Lamp
7
The external inductor (L) selection for a D356B circuit greatly affects the output capability and current draw of the
driver. A careful designer will balance current draw considerations with output performance in the choice of an ideal
inductor for a particular application. Figures 3, 4, and 5 show typical brightness and current draw of a D356B circuit with
different inductor values, lamp sizes, and supply voltages. Please note that the DC resistance (DCR) of inductors with
the same nominal inductance value may vary with manufacturer and inductor type. Thus, inductors made by a different
manufacturer may yield different outputs, but the trend of the different curves should be similar. Lamp luminance is also
a function of lamp size. In each example, a larger lamp will have less luminance with approximately the same current
draw.
II. Inductor (L) Selection
Figure 3: V+=1.5V, 1 in
2
EL Lamp
Figure 4: V+=3.0V, 1 in
2
EL Lamp
Figure 5: V+=5.0V, 4 in
2
EL Lamp
0
2
4
6
8
10
12
0
1
2
3
4
5
Inductor (mH)
0
8
16
24
32
40
48
Luminance
Current
Lamp Luminance (ftL)
Current (mA)
0
2
4
6
8
10
12
0
1
2
3
4
5
Inductor (mH)
0
8
16
24
32
40
48
Luminance
Current
Lamp Luminace (ftL)
Current (mA)
0
2
4
6
8
10
12
0
2
4
6
8
10
Inductor (mH)
0
8
16
24
32
40
48
Luminance
Current
Lamp Luminance (ftL)
Current (mA)
D356B Design Ideas
I. Driving Multi-segment Lamps
The D356B may be used to drive two or more EL lamps or EL lamp areas independently. An external switching circuit
can be used to turn each lamp segment on or off. A high signal at the E input for the corresponding EL lamp will power
the segment when the IC is enabled. In this example, Segment 1 is always on when the Durel D356B is enabled.
Otherwise, always make sure that at least one segment is switched on when the driver IC is activated.
8
II. Two-Level Dimming
Toggle switching between two different EL lamp brightness levels may be achieved with the following circuit. When
DIM is low, the external pnp transistor is saturated and the EL lamp runs at full brightness. When DIM is high, the
external pnp turns off and the 47W resistor reduces the voltage at (V+) and dims the EL lamp.
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
L
V
bat
CLF
D356
EL Lamp
Segment 2
EL Lamp
Segment 1
EL Lamp
Segment 3
1.0uF
E2
2.2K
4.7K
BAS21LT1
BAS21LT1
MMBT5401LT1
MMBT5551LT1
1K
E3
2.2K
4.7K
BAS21LT1
BAS21LT1
MMBT5401LT1
MMBT5551LT1
1K
100 nF
100 nF
OFF
ON
OFF
ON
OFF
ON
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
EL Lamp
L
V
bat
CLF
D356
47
1k
DIM
1.0
u
F
2N3906
Low B
High B
GND
3.0V
OFF
ON
III. Lamp Frequency Control with an External Clock Signal
An external clock signal may be used to control the EL lamp frequency (LF). This technique allows the designer
flexibility to synchronize the El driver IC with other elements in the application. The output lamp frequency will be the
same frequency as the input clock signal. For example, if a 250Hz input clock signal is used, the resulting lamp
frequency will be 250Hz. The clock signal voltage should not exceed V+.
IV. EL Lamp Brightness Regulation
Regulating the DC supply input voltage to the D356 will result in a constant brightness level from the EL lamp,
regardless of battery voltage. In this example, a Micrel voltage regulator is used.
9
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
EL Lamp
L
V
bat
D356
150k
Lamp Frequency CLK
0.2V Max
1.0V Min
1.0
u
F
OFF
ON
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
EL Lamp
L
CLF
D356
1.0
u
F
V
bat
1 GND
2 E
OUT
IN
4
3
MIC5203
E
OFF
ON
V. High EL Brightness Through Supply Voltage Doubling (Option 1)
Maximum brightness from a D356 is achieved at relatively high supply voltages (>3.0V). An external voltage boost
circuit may be used to increase the voltage supplied to the D356. In the following circuit, the National Semiconductor
LM2665 is used to double the voltage supplied to the D356. This can produce about twice the brightness of the D356
alone.
10
VI. High EL Brightness Through Supply Voltage Doubling (Option 2)
In many cases, a resistor may replace the diode in the previous circuit. The diode is used by the LM2665 during
startup (see LM2665 datasheet). The circuit below ensures that the LM2665 starts properly before the D356 is
turned on.
2
3
4
7
6
5
L-
VOUT
L+
1
8
GND
E
CLF2
CLF1
V+
EL Lamp
L
CLF
D356
V
bat
1 V
BAT
3 CAP-
2 GND
CAP+
SD
6
4
5
OUT
V
bat
LM2665
3.3
u
F
3.3
u
F
1N914
OFF
ON
OFF
ON
2
3
4
7
6
5
L-
VOUT
L+
1
8
GND
E
CLF2
CLF1
V+
EL Lamp
L
CLF
D356
V
bat
1 V
BAT
3 CAP
-
2 GND
CAP+
SD
6
4
5
OUT
V
bat
270K
V
bat
LM2665
3.3
u
F
3.3
u
F
OFF
ON
VII. High EL Brightness With Parallel D356 (Option 1)
Two or more D356 EL drivers may be operated in parallel to increase the brightness of the EL lamp by 50-100%. In
this circuit, an external clock signal with 50% duty cycle is needed to synchronously drive both D356 ICs. The
clock signal voltage should not exceed V+.
11
VIII. High EL Brightness With Parallel D356 (Option 2)
Two or more D356 EL drivers may be operated in parallel to increase the brightness of the EL lamp by 50-100%. In
this circuit, two D356 ICs are operating synchronously using their internal oscillators. The lamp frequency is
controlled by a shared CLF capacitor.
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
L
CLF
D356
EL Lamp
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
L
D356
100
100
1.0
F
Vbat
OFF
ON
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
EL Lamp
L
D356
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E
CLF2
CLF1
V+
L
D356
150k
Lamp Frequency CLK
0.2V Max
1.0V Min
150k
1.0
F
Vbat
OFF
ON
The D356B IC is available as bare die in probed wafer form or in die tray, and in standard MSOP-8 plastic package
per tube or per tape and reel. A Durel D356B Designer's Kit (1DDD356BB-K01) provides a vehicle for evaluating
and identifying the optimum component values for any particular application using D356B. Durel engineers also
provide full support to customers, including specialized circuit optimization and application retrofits.
MSOPs in Tape and Reel:
1DDD356BB-M02
RECOMMENDED PAD LAYOUT
DUREL Corporation
2225 W. Chandler Blvd.
Chandler, AZ 85224-6155
Tel: (480) 917-6000
FAX: (480) 917-6049
Website: http://www.durel.com
2001 Durel Corporation
Printed in U.S.A.
LIT-I 9039 Rev. A01
The DUREL name and logo are registered trademarks of DUREL CORPORATION.
This information is not intended to and does not create any warranties, express or implied, including any warranty of merchantability or fitness for a
particular purpose. The relative merits of materials for a specific application should be determined by your evaluation.
This inverter is covered by the following U.S. patents: #5,313,141, #5,347,198; #6,043,610. Corresponding foreign patents are issued and pending.
ISO 9001 Certified
Ordering Information
MSOPs are marked with part number (356B) and 3-digit wafer lot
code. Bottom of marking is on the Pin 1 side.
F
H
I
A
B
G
C
D
E
Embossed tape on 360 mm diameter reel per EIA-481-2.
2500 units per reel. Quantity marked on reel label.
Tape Orientation
e
c
a
b
d
f
A
0.94
0.037
1.02
0.040
1.09
0.043
B
0.05
0.002
0.10
0.004
0.15
0.006
C
0.20
0.008
0.33
0.013
0.46
0.018
D
0.41
0.016
0.53
0.021
0.65
0.026
E
0.13
0.005
0.18
0.007
0.23
0.009
F
2.84
0.112
3.00
0.118
3.15
0.124
G
0.43
0.017
0.65
0.026
0.83
0.033
H
4.70
0.185
4.90
0.193
5.11
0.201
I
2.84
0.112
3.00
0.118
3.25
0.128
Description
mm.
in.
mm.
in.
mm.
in.
MSOP-8
Min.
Typical
Max.
mm.
in.
mm.
in.
mm.
in.
Min.
Typical
Max.
a
0.60
0.0236
0.6
0.0256
0.70
0.0276
b
1.90
0.0748
1.9
0.0768
2.00
0.0788
c
3.3
0.130
3.45
0.136
d
0.89
0.035
0.9
0.038
1.05
0.041
e
5.26
0.207
5.41
0.213
f
0.41
0.016
0.4
0.018
0.51
0.020
MSOP-8 PAD LAYOUT
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