| Surface mount diac with fixed voltage reference |
 |
| Datasheet
| Orderable
Products | Features
and Description |
| |
| Datasheet |
| Reference |
Title |
| SMDB3 |
Diac
(10 Dec 2001, 59KB) Download |
|
| |
| Orderable Products |
| Device |
Status |
RoHS |
Package |
Purchase |
| SMDB3 |
Active |
Converted |
SOT 3 |
 |
| DB3 |
Active |
Converted |
DO35 2 |
|
| DB4 |
Active |
Converted |
DO35 2 |
|
|
 |
| Features and Description |
 |
Dynamic behaviour |
| |
With a rise time tr max
of 0.2µs, the SMDB3 presents, as
shown in the figure below, a faster response compared to
the DB3 device, which is translated by a gain for the dynamic
breakover voltage Delta V and for the Peak current IP |
|
Leakage current |
| |
The planar technology
has also allowed the reduction of the leakage current IR
by a factor 10, moving to 1µA |
|
|
|
Comparative voltage and current response behavior between
SMDB3 and DB3 |
|
| A widely used component in power applications
is the DIAC which is found in a great number of industrial
applications such as hand tools and in lighting applications,
specifically electronic lamp ballasts, the electric transformer
for halogen lamps and light dimmers. Functioning as a trigger diode
with a fixed voltage reference, the DIAC can be used in conjunction
with triacs for simplified gate control circuits or as a starting
element of power oscillator in fluorescent lamp ballasts. STMicroelectronics
offers a device produced with the planar process and available
in the small SOT-23 package, providing new parametric features,
reduced space, and full compatibility with automatic pick and place
equipment. |
| Application advantages: |
| The shorter rise time tr means that more energy can
be transferred at the start of the oscillator in lighting applications,
guarantying a faster and more reliable start. This is particularly
interesting for CFL (Compact Fluorescent Lamps) and electronic lamp
ballast with the improvement of the start-up phase and the reliability
of the DC/AC converter, and also for electric transformers for low
voltage halogen lamps, where the SMDB3
is solicited every 10ms to re-start the DC/AC converter. When used
for triac triggering in hand tools, the SOT-23 package allows the
component to be located in the trigger button of the device. Eventually,
the 3-lead package allows the SMDB3 to be used as a standard bi-directional
diac or as two half diacs, depending on the pin connection, as shown
on the figure opposite. |
 |
|
Half diacs behaviour |
|
| Benefits: |
|
Reduced board space |
|
Fast response time |
|
High energy transfer |
|
Standard surface mount assembly |
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