ꢀꢁꢁ ꢂ ꢃꢄ ꢅ ꢆ ꢀꢁꢁ ꢂ ꢃꢄ ꢇ ꢆ ꢀ ꢁꢁ ꢂꢃ ꢄꢄ
ꢀꢁꢁ ꢈ ꢃꢄ ꢅ ꢆ ꢀꢁꢁ ꢈ ꢃꢄ ꢇ ꢆ ꢀ ꢁꢁ ꢈꢃ ꢄꢄ
SLUS499A – NOVEMBER 2001 – REVISED JANUARY 2002
APPLICATION INFORMATION
PZT operation
Ceramic piezoelectric transformers were first proposed by C.A. Rosen in 1956. Unlike magnetic transformers
that rely on electromagnetic energy transfer, PZTs transfer electric potential to mechanical force as shown in
Figure 6. The electrical-to-mechanical conversion of energy is referred to as the reverse piezoelectric effect
whereas the mechanical-to-electrical energy conversion is referred to as the direct piezoelectric effect.
MECHANICAL
FORCE
ELECTRIC
POTENTIAL
MECHANICAL
FORCE
ELECTRIC
POTENTIAL
+
+
UDG–01099
Figure 6. Piezoelectric Effect
Each manufacturer has a unique recipe of materials and structural layering that determine their PZT’s operating
characteristics. Common materials used to make PZTs include lead zirconate, lead titanate and lithium niobate.
Single layer PZTs are less costly and easier to manufacture, but have a lower voltage gain (typically 5 to 10 )
and may require a step-up magnetic transformer in order to operate the lamp. Multi-layered PZT designs are
more difficult to manufacture, but have a higher voltage gain (20 to 70) allowing a CCFL to be driven using
conventional off-the-shelf inductors.
9
www.ti.com
TI [ TEXAS INSTRUMENTS ]
