SBST C&D Technologies., SBST Datasheet - Page 5

• Manufacturer Part Number: SBST
• Description: Dc/dc Converter
• Manufacturer: C&D Technologies.

1150 Eglinton Avenue East
Toronto, Ontario M3C 1H7
1-866-740-1232
SBST_084-SBST-00_RevH_Jan18-2005.fm
External Capacitance for the Boost SIP Product
All SIP products require external capacitors to be placed on the system board that the SIP will be designed
into. The following guidelines should be applied to choose the external capacitors for the Boost SIP.
Input Capacitance
More relaxed requirements apply to the input capacitor.
A capacitor having at least 200µF has to be used. The capacitor must be able to handle the input AC ripple
current. For the boost SIP, this can be approximated to 20% of the output current.
There is no specific requirement for ESR. The Boost SIP operation is not affected by this parameter. To
minimize input voltage ripple the user may select to use a low ESR capacitor as well. An ESR lower than
0.05 Ω is recommended.
Output Capacitance
The capacitor must be able to handle the AC ripple current. A conservative rule is to assume this is roughly
equal to the output current of the boost SIP. If the boost is used to provide 5A, then the output capacitor’s
allowable ripple current needs to be at least 5A. If one capacitor’s allowable ripple current is less than 5A,
then several capacitors have to be used so the total allowable ripple current is at least 5A.
The capacitor needs to have a low ESR (Equivalent Series Resistance) to help reduce the output voltage
ripple.
The capacitance value should be at least 470µF, but due to the ripple current and ESR requirements the
actual capacitors may end up having a much larger total capacitance.
A rough calculation of the needed ESR can be done using the formula:
Where:
Example: Assume the Boost SIP provides a maximum current of 5A and the voltage ripple needs to
be lower than 0.1V peak to peak.
ESR = Capacitor’s equivalent series resistance ( Ω )
V
I
OUT
RIPPLE
= Output current (A)
= Desired output voltage ripple (Vpk - to - pk)
ESR =
ESR =
www.cdtechno-cps.com
______________
_____
2 x 5
0.1
V
2 x I
Programmable, Single Output, 1.1V - 1.85Vout @ 60A
RIPPLE
= 0.01 Ω
OUT
3.3V Input, 5.0V Output, 5A
DC/DC Converter
4607 S.E. International Way
Milwaukie, Oregon 97222
DC/DC Converter
1-971-206-2800
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