aoz1341ei-1 Alpha & Omega Semiconductor, aoz1341ei-1 Datasheet - Page 8

• Manufacturer Part Number: aoz1341ei-1
• Description: Single Channel Usb Switch
• Manufacturer: Alpha & Omega Semiconductor

Applications Information
Input Capacitor Selection
The input capacitor prevents large voltage transients
from appearing at the input, and provides the
instantaneous current needed each time the switch turns
on and to limit input voltage drop. The input capacitor
also prevents high-frequency noise on the power line
from passing through the output of the power side. The
choice of the input capacitor is based on its ripple current
and voltage ratings rather than its capacitor value. The
input capacitor should be located as close to the V
as possible. A 1 μF and above ceramic cap is
recommended. However, higher capacitor values further
reduce the voltage drop at the input.
Output Capacitor Selection
The output capacitor acts in a similar way. A small 0.1 μF
capacitor prevents high-frequency noise from going into
the system. Also, the output capacitor has to supply
enough current for a large load that it may encounter
during system transients. This bulk capacitor must be
large enough to supply fast transient load in order to
prevent the output from dropping.
Rev. 1.3 July 2011
IN
www.aosmd.com
pin
Power Dissipation Calculation
Calculate the power dissipation for normal load condition
using the following equation:
P
The worst case power dissipation occurs when the load
current hits the current limit due to over-current or short
circuit faults. The power dissipation under these
conditions can be calculated using the following
equation:
P
Layout Guidelines
Good PCB layout is important for improving the thermal
and overall performance of the AOZ1310. To optimize the
switch response time to output short-circuit conditions
keep all traces as short as possible to reduce the effect of
unwanted parasitic inductance. Place the input and
output bypass capacitors as close as possible to the IN
and OUT pins. The input and output PCB traces should
be as wide as possible for the given PCB space. Use a
ground plane to enhance the power dissipation capability
of the device.
D
D
= R
= (V
ON
IN
– V
x (I
OUT
OUT
)
) x I
2
LIMIT
AOZ1310
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