General Description:
The Durel
D340B 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 low-cost, regulated device is
well suited for backlighting timepieces and small liquid crystal
displays for portable electronic applications.
Data Sheet
D340B
Electroluminescent
Lamp Driver IC
D
1
34
B
MSOP-8
Features
•
•
•
•
Small System Footprint
Regulated AC output voltage
Low Standby Current
High Efficiency
•
•
•
•
Applications
Timepieces
Pagers
Calculators
Handsets
Lamp Driver Specifications:
(Using Standard Test Circuit at Ta=25 °C unless otherwise specified.)
Parameter
Standby Current
Supply Current
Output Voltage
Lamp Frequency
Symbol
I
Vout
LF
Minimum
110
100
Typical
5
12
144
140
Maximum
1000
20
160
200
Unit
nA
mA
Vpp
Hz
Conditions
E’ = V+
E’ = GND
E’ = GND
E’ = GND
Standard Test Circuit
1
3.3 V
4.7 uF
OFF (3.0 V)
ON
V+
L+
8
2
E’
VOUT
7
4.7 mH
(59 Ohm DCR)
3
GND
L-
6
4
N/C
D340B
N/C
5
LOAD B
1
Load A*
47 nF
100
Ω
10kΩ
22 nF
Typical Output Waveform
* Load B approximates a 5in
2
(32 cm
2
) EL lamp.
Absolute Maximum Ratings:
Parameter
Supply voltage
Operating Range
Withstand Range
Enable Voltage
Output Voltage
Operating Temperature
Storage Temperature
Symbol
V+
E
V
OUT
T
a
T
s
Minimum
1.0
- 0.5
- 0.5
- 40
- 40
Maximum
7.0
10.0
(V+) +0.5
160
70
150
Unit
V
V
Vpp
°C
°C
Comments
E = GND
E = V+
Peak-to-Peak Voltage
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
FUNCTION
DC power supply input
System enable; Power Down Control
System ground connection
No connection
No connection
Negative input to inductor
High voltage AC output to lamp
Positive input to inductor
1
2
3
4
8
7
6
5
1
2
3
4
5
6
7
8
V+
E’
GND
N/C
N/C
L-
V
OUT
L+
Note: Please consult factory for bare die dimensions and bond
pad locations.
2
Typical Performance Characteristics Using Standard Test Circuit
400
350
300
250
200
150
100
50
0
1
2
3
4
5
6
7
DC Input Voltage
400
350
300
250
200
150
100
50
0
-40
-20
0
20
40
60
80
Temperature ( C)
Output Frequency vs. DC Supply
Voltage
Output Frequency vs. Ambient
Temperature
200
200
Output Voltage (Vpp)
1
2
3
4
5
6
7
Output Voltage (Vpp)
160
120
80
40
0
DC Input Voltage
160
120
80
40
0
-40
-20
0
20
40
60
80
Temperature ( C)
Output Voltage vs. DC Supply Voltage
Output Voltage vs. Ambient
Temperature
30
25
20
15
10
5
0
1
2
3
4
5
6
7
DC Input Voltage
30
25
20
15
10
5
0
-40
-20
0
20
40
60
80
Temperature ( C)
Supply Current vs. DC Supply Voltage
Supply Current vs. Ambient
Temperature
3
Block Diagram of the Driver Circuitry
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 D340B 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. When the voltage on the lamp reaches the set voltage on the comparator, 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, and
off-chip components. The on-chip logic controls the inductor switching frequency (HF) and change in lamp charging
polarity at a frequency (LF) that is dependent on the lamp load size and DC voltage source. 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 D340B Designer’s Kit, which includes a printed circuit evaluation board intended to aid you in
developing an EL lamp driver configuration using the D340B that meets your requirements. A section on designing
with the D340B is included in this datasheet to serve as a guide to help you select the appropriate external components
to complete your D340B EL driver system.
Typical D340B 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
RF/Wirelessly
京公网安备 11010802033920号
EEWORLD
