LTC3225-1_15 Datasheet, PDF (10/14 Pages) Linear Technology – 150mA Supercapacitor Charger

LTC3225/LTC3225-1
APPLICATIONS INFORMATION
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 flying 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 fields can
also be generated if the flying 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.
LTC3225
LTC3225-1 ₁₀
C_OUT
3
C_X
8, 11
GND
C1 = C2 ≥ 100μF
V_OUT
C1
C_SUP
C2
3225 F03
Figure 3. Charging a Single Supercapacitor
3225fb
10