1. Durel IC Drivers
All Durel drivers are available as bare die, or in MSOP8 package form in tape and reel. The Durel D340 is the smallest IC available from Durel and is ideal for watch applications. It is proven to work at higher voltages making it also suitable for large LCD backlighting applications. The D340 requires only one external component - an inductor.
The D355 is a new driver that offers superior efficiency and a wide operating voltage range. With increased power delivery capability, the D355 is ideally suited for large watches, mid-sized LCD's, and handset applications.
The D305 is the most powerful inverter on the market today.
The D365, D371, D372, and D381 low-noise EL drivers are based on a patented circuit designed to reduce EMI/RFI and mechanical noise for sensitive applications such as handsets and other commercial products.
2019/2/22
* Covered under one or more of the following patents -- 5,313,141; 5,780,975; 5,789,870

2. Durel 3-Port Circuit Switch Mode - “3P” Integrated Circuit
Proprietary 3P topology:
Provides shared common ground for improved EMI/RFI and audible noise management
Eliminates need for 3 layer lamps or additional shielding
Simplifies solution for driving multiple lamp segments
Switch Mode - “3P”
EL requires AC Power. There are two methods for converting DC voltage to AC voltage. Transformers offer superior power delivery capability but are too large for most consumer applications. Durel has developed a line of IC based pumping-inductor drivers based on our patented "3P" design. The "3P design enables the use of a common I/O - reducing the number of interconnections. In applications such as watches, the watch case itself can be used as the common, simplifying the design.
Integrated Circuit
2019/2/22

3. Advantages of Durel EL Drivers
Patented 3P topology
Shared common ground provides improved EMI/RFI and audible noise management
Eliminates need for 3 electrode lamps
Simplicity when driving multiple lamp segments
High level of integration
Proven low variability in high volume applications
Large foundry partners ensure quality product and stable source of supply
2019/2/22

4. Noise Sources EMI/RFI Mechanical
Can be handled using good EE practices.
Mechanical
Electrostrictive
Electrostatic
There are two types of noise; EMI/RFI and Mechanical.
EMI/RFI noise is proven to be handled by the application of good electrical engineering principals.
The Mechanical noise is actually made up of two different sources - Electrostrictive and Electrostatic.
2019/2/22

5. Durel Low-Noise EL Drivers
Noise Signal of EL Lamp on Typical Chip Driver
dV/dt reduced during L discharge
electrical noise minimized
quieter EL lamp output
This chart illustrates the noise reduction feature in a low-noise EL driver. The first chart shows the wave form output of a typical EL lamp driver and the corresponding noise produced by this system. It is obvious that the majority of the noise generated is produced by the backside of the waveform when a large amount of energy is being transferred.
The patented low-noise EL driver decrease the slope of the backside of this curve, controlling the transfer of the energy and reducing the amount of noise generated.
Additional notes:
These are oscilloscope readings of the following:
Channel 1: Output voltage waveform from a Durel D365 “Stealth” chip inverter driving an EL lamp at about 230 Hz lamp frequency and 265Vpp. Notice that the slope of the voltage discharge part of the lamp voltage cycle is reduced; the output voltage is discharged over a longer period of time.
Channel 2: Sound pressure level (SPL) produced by the lamp is measured with a piezoelectric device which converts the mechanical movement to the electrical signal shown in channel 2. In this case, the RMS reading for the noise is 22mV, which correlates to approximately 60dB SPL. This is almost a 6dB reduction in noise level, which means that the audible noise from the lamp is 25% of its original level. In some cases, the reduced level of noise may already be below the audible range of sound for a population.
Noise Signal of EL Lamp on D365* Low-Noise IC Driver
2019/2/22
* Covered under one or more of the following patents -- 5,313,141; 5,780,975; 5,789,870

6. Solutions for Mechanical Noise
Reduce or eliminate audible noise by:
Using integrated low noise EL driver
(e.g. Durel D365, D371,D372, D381)
Noise-dampening materials and adhesives
Electrical isolation (3P driver or additional ground layers/planes)
Using appropriate inductor
Using high performance HV cap
2019/2/22

7. Solutions for Electrical Noise
Avoid EMI/RFI noise by:
Practicing fundamental EE techniques.
Bypass cap
Tight layout
Ground and power planes
Faraday shielding, where appropriate
Using 3-port EL driver output
Using low noise EL drivers
There are two types of noise; EMI/RFI and Mechanical.
EMI/RFI noise is proven to be handled by the application of good electrical engineering principals.
The Mechanical noise is actually made up of two different sources - Electrostrictive and Electrostatic.
D365
D371
D381
D372
2019/2/22

8. Wave-shapingTM Feature of the D371, D372, D381, D305
Optimize output waveform for lower noise
Control dV/dt during lamp discharge cycle to compensate for EL lamp size, frequency, or peak voltage
2019/2/22
* Covered under one or more of the following patents -- 5,313,141; 5,780,975; 5,789,870