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General Description:
The DurelO 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
B
D
6 35
MSOP-8
Features
* * * * * High Efficiency Low Voltage Operation Small System Footprint Controlled Current Discharge for Low EMI Capacitor or External Clock LF Control * * * *
Applications
Watches Data Organizers/PDAs Pagers LCD and Keypad Backlighting
Lamp Driver Specifications:
(Using Standard Test Circuit at Ta=25 C unless otherwise specified.)
Parameter
Standby Current Supply Current Enable Current Output Voltage Lamp Frequency Inductor Frequency
Symbol
I Vout LF HF
Minimum
Typical
10 23 50 135 310 23
Maximum
100 30 75 220 390
Unit
nA mA uA Vpp Hz kHz
Conditions
E = GND E = 3.0V E = 3.0V CLF=5.0 nF
110 230
Standard Test Circuit
1 2
1.8mH (3 Ohms)
GND LVOUT L+
D356B
E CLF2 CLF1 V+
8 7
GND OFF
3.0V ON
5.0nF
3 4
6 5
0.1m H
Load B
3.0 Vdc
1
Load B*
47 nF 100W 10kW 22 nF
Typical Output Waveform
* Load B approximates a 5in2 EL lamp.
Absolute Maximum Ratings:
Parameter Supply voltage Operating Range Withstand Range Enable Voltage Output Voltage CLF Voltage Operating Temperature Storage Temperature Symbol V+ E Vout VCLF Ta Ts Minimum 1.0 -0.5 -0.5 0 -40 -65 Maximum 7.0 10.0 (V+) +0.5 220 (V+) +0.3 85 150 Unit V V Vpp V C C Comments E = V+ E = GND Peak-to-peak voltage External clock input
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.
Physical Data:
PIN # NAME
1 2 3 4 8 7 6 5
1 2 3 4 5 6 7 8 GND LVOUT L+ V+ CLF1 CLF2 E
FUNCTION
System ground connection Negative input to inductor High voltage AC output to lamp Positive input to inductor DC power supply input Lamp frequency capacitor/clock input Lamp frequency capacitor/clock input System enable
Note: Please consult factory for bare die dimensions and bond pad locations.
2
Typical Performance Characteristics Using Standard Test Circuit
450 400 350 300 250 200 150 100 50 0 1 2 3 4 5 6 7 DC Input Voltage
450 400 350 300 250 200 150 100 50 0 -40 LF (Hz)
LF (Hz)
-20
0
20
40
60
80
Output Frequency vs. DC Supply Voltage
Tem perature ( C)
Output Frequency vs. Ambient Temperature
240
240 Output Voltage (Vpp) 200 160 120 80 40 0 -40 -20 0 20 40 60 80
Output Voltage (Vpp)
200 160 120 80 40 0 1 2 3 4 5 6 7 DC Input Voltage
Tem perature ( C)
Output Voltage vs. DC Supply Voltage
Output Voltage vs. Ambient Temperature
50 Avg Supply Current (mA) 40 30 20 10 0 1 2 3 4 5 6 7 DC Input Voltage Avg Supply Current (mA)
50 40 30 20 10 0 -40 -20 0 20 40 60 80 Tem perature ( C)
Supply Current vs. DC Supply Voltage
Supply Current vs. Ambient Temperature
3
Block Diagram of the Driver Circuitry
1.0 m F
E
V+
L+
CLF1 CLF2
Low Frequency Oscillator
High Frequency Oscillator
L-
VOUT
GND
EL Lamp
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.
4
Typical D356B EL Driver Configurations
1.5V Analog Watch
1 GND LVOUT L+
D356
2
E CLF2 CLF1 V+
8 7
1.5V ON GND OFF
Typical Output
Luminance= 3.5 fL (12 cd/m2) Lamp Frequency = 220 Hz Supply Current = 19 mA Vout = 190 Vpp Load = 1 in2 Durel(R)3 Green EL
1.0 mH Murata LQS33C-102
2 3 4
6.8 nF
6 5
1.0 m F 1.5 V
1 in EL Lamp
3.0 V Handset LCD or Digital Watch Typical Output
Luminance = 8.6 fL (29.5 cd/m2) Lamp Frequency = 360 Hz Supply Current = 12 mA Vout = 218 Vpp Load = 1 in2 Durel(R)3 Green EL
3.0V
1 2
3.9 mH Sumida CLS62-392
GND LVOUT L+
D356
2
E CLF2 CLF1 V+
8 7
ON GND OFF
4.7 nF
3 4
6 5
1.0 m F 3.0 V
1 in EL Lamp
5.0 V PDA
1 GND LVOUT L+
D356
2
5.0V
E CLF2 CLF1 V+
8 7
ON GND OFF
Typical Output
Luminance = 7.7 fL (26.4 cd/m2) Lamp Frequency = 330 Hz Supply Current = 25 mA Vout = 200 Vpp Load = 4 in2 Durel(R) Green EL
2
3.3 mH Bujeon BDS-4020SBL
4.7 nF
3 4
6 5
1.0 m F 5.0 V
4 in EL Lamp
5
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.
900 800 Lamp Frequency (Hz) 700 600 500 400 300 200 100 0 0 1 2 3 4 5 6 CLF (nF) 7 8 9 10
Figure 1: Typical Lamp Frequency vs. CLF Capacitor 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.
8 7 6 5 4 3 2 1 0 0 200 400 600 800 1000 Lamp Frequency (Hz)
Lamp Luminane (fL)
2in2 EL Lamp 4in2 EL Lamp 6in2 EL Lamp
Figure 2: Typical Lamp Luminance vs. Lamp Frequency
6
II. Inductor (L) Selection
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.
12
48
Lamp Luminace (ftL)
Luminance Current
12 10 8 6 4 2 0 0 1 2 3 Inductor (mH) 4 5
48 40 32 24 16 Luminance Current 8 0
Lamp Luminance (ftL)
10 8 6 4 2 0 0 1 2
40
Current (mA)
32 24 16 8 0
3 4 5
Inductor (mH)
Figure 3: V+=1.5V, 1 in2 EL Lamp
Figure 4: V+=3.0V, 1 in2 EL Lamp
12
48
Luminance
Lamp Luminance (ftL)
8 6 4 2 0 0 2 4 6 8 10
32 24 16 8 0 Inductor (mH)
Figure 5: V+=5.0V, 4 in2 EL Lamp
Current (mA)
10
Current
40
7
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.
1 GND 2 LL
E
8
ON OFF
CLF2 7
CLF
3 VOUT 4 L+
D356
CLF1 6 V+ 5
1.0uF Vbat
EL Lamp Segment 1
EL Lamp Segment 2
BAS21LT1 BAS21LT1
EL Lamp Segment 3
BAS21LT1 E3 4.7K MMBT5551LT1
BAS21LT1
ON E2 OFF 2.2K 4.7K
ON OFF 2.2K
MMBT5551LT1 MMBT5401LT1 1K 100 nF MMBT5401LT1 1K 100 nF
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.
ON
1 2
L
GND LVOUT L+
D356
E CLF2 CLF1 V+
8 7
OFF
DIM
High B GND
Low B 3.0V
1k CLF
3 4
6 5
1.0uF 47
2N3906
Vbat
EL Lamp
8
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+.
1 2
L
GND LVOUT L+
D356
E CLF2 CLF1 V+
8
OFF
ON
7 6 5
Lamp Frequency CLK 1.0V Min 150k 0.2V Max
3 4
EL Lamp
1.0uF
Vbat
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.
1 GND OUT 4
E
ON
2E
MIC5203
IN 3
Vbat
OFF
1 GND 2 LL
E
8
CLF
CLF2 7 CLF1 6
D356
3 VOUT 4 L+
V+ 5
1.0uF
EL Lamp
9
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.
3.3uF Vbat
1 V BAT CAP+ 2 GND
V bat
6 5 4
1N914
OFF ON ON
OUT SD
3 CAPLM2665
1 2
L
GND LVOUT L+
D356
E CLF2 CLF1 V+
8
OFF
7
CLF
3 4
6 5
3.3uF
EL Lamp
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.
3.3uF Vbat
1 V BAT CAP+ 2 GND
V bat
6 5
270K
OUT SD
OFF
3 CAP1 2
L
4
ON
LM2665
GND LVOUT L+
E CLF2 CLF1 V+
8 7
Vbat
CLF
3 4
6 5
3.3u F
D356
EL Lamp
10
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+.
1 GND 2 LL
E
8
OFF
ON
CLF2 7 CLF1 6
D356 150k
3 VOUT 4 L+
V+ 5
Lamp Frequency CLK 1.0V Min
1 GND 2 LL
E
8
0.2V Max
CLF2 7 CLF1 6
D356 150k
3 VOUT 4 L+
V+ 5
1.0F Vbat
EL Lamp
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 GND 2 LL
E
8
CLF2 7 CLF1 6
D356
ON
3 VOUT 4 L+
V+ 5
OFF
1 GND 2 LL
E
8
CLF
CLF2 7 CLF1 6
D356
3 VOUT 4 L+
V+ 5
1.0F Vbat
100
100
EL Lamp
11
Ordering Information
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.
F
MSOP-8
Min.
Description mm. in. mm.
Typical
in. mm.
Max.
in.
I D C E A G B
H
A B C D E F G H I
0.94 0.05 0.20 0.41 0.13 2.84 0.43 4.70 2.84
0.037 0.002 0.008 0.016 0.005 0.112 0.017 0.185 0.112
1.02 0.10 0.33 0.53 0.18 3.00 0.65 4.90 3.00
0.040 0.004 0.013 0.021 0.007 0.118 0.026 0.193 0.118
1.09 0.15 0.46 0.65 0.23 3.15 0.83 5.11 3.25
0.043 0.006 0.018 0.026 0.009 0.124 0.033 0.201 0.128
RECOMMENDED PAD LAYOUT
b a
MSOPs are marked with part number (356B) and 3-digit wafer lot code. Bottom of marking is on the Pin 1 side.
MSOP-8 PAD LAYOUT
Min.
mm. in. mm.
Typical
in. mm.
Max.
in.
c
e
d f
a b c d e f
0.60 1.90 3.3 0.89 5.26 0.41
0.0236 0.0748 0.130 0.035 0.207 0.016
0.6 1.9 0.9 0.4
0.0256 0.0768 0.038 0.018
0.70 2.00 3.45 1.05 5.41 0.51
0.0276 0.0788 0.136 0.041 0.213 0.020
MSOPs in Tape and Reel: 1DDD356BB-M02
Tape Orientation
Embossed tape on 360 mm diameter reel per EIA-481-2. 2500 units per reel. Quantity marked on reel label.
ISO 9001 Certified
DUREL Corporation
2225 W. Chandler Blvd. Chandler, AZ 85224-6155 Tel: (480) 917-6000 FAX: (480) 917-6049 Website: http://www.durel.com
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.
(c) 2001 Durel Corporation Printed in U.S.A. LIT-I 9039 Rev. A01

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