LTC3225/LTC3225-1
10
3225fb
Table 1 contains a list of ceramic capacitor manufacturers
and how to contact them.
Table 1. Capacitor Manufacturers
AVX www.avx.com
Kemet www.kemet.com
Murata www.murata.com
Taiyo Yuden www.t-yuden.com
Vishay www.vishay.com
TDK www.component.tdk.com
Layout Considerations
Due to the high switching frequency and high transient
currents produced by the LTC3225/LTC3225-1, careful
board layout is necessary for optimum performance. An
unbroken ground plane and short connections to all the
external capacitors improves performance and ensures
proper regulation under all conditions.
The voltages on the fl ying capacitor pins C
+
and C
–
have
very fast rise and fall times. The high dV/dt values on
these pins can cause energy to capacitively couple to
adjacent printed circuit board traces. Magnetic fi elds can
also be generated if the fl ying capacitors are far from the
part (i.e. the loop area is large). To prevent capacitive
energy transfer, a Faraday shield may be used. This is a
grounded PC trace between the sensitive node and the
LTC3225/LTC3225-1 pins. For a high quality AC ground it
should be returned to a solid ground plane that extends
all the way to the LTC3225/LTC3225-1.
Table 2. Supercapacitor Manufacturers
CAP-XX www.cap-xx.com
NESS CAP www.nesscap.com
Maxwell www.maxwell.com
Bussmann www.cooperbussmann.com
AVX www.avx.com
Illinois Capacitor www.illcap.com
Tecate Group www.tecategroup.com
Charging a Single Supercapacitor
The LTC3225/LTC3225-1 can also be used to charge a
single supercapacitor by connecting two series-connected
matched ceramic capacitors with a minimum capacitance
of 100µF in parallel with the supercapacitor as shown in
Figure 3.
APPLICATIONS INFORMATION
Figure 3. Charging a Single Supercapacitor
C1
C
SUP
V
OUT
C1 = C2 ≥ 100µF
C2
10
3
8, 11
3225 F03
LTC3225
LTC3225-1
C
OUT
C
X
GND
