RT8105 查看數據表（PDF） - Richtek Technology
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RT8105 Datasheet PDF : 12 Pages
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` Placing the ceramic capacitors physically close to the
drain of the high side MOSFET. This can reduce the
input voltage drop when high side MOSFET is turned
on.
` Keep the high-current loops as short as possible. The
current transition between MOSFETs usually causes
di/dt voltage spike due to the parasitic components on
PCB trace and component lead. Therefore, making the
trace length between power MOSFETs and inductors
wide and short can reduce the voltage spike and also
reduce EMI.
` Make MOSFET gate driver path as short as possible.
Since the gate driver uses high-current pulses to switch
on/off power MOSFET, the driver path must be short to
reduce the trace inductance. This is especially important
for low side MOSFET because this can reduce the
possibility of shoot-through. Besides, also make the
width of gate driving path as wide as possible to reduce
the trace resistance.
` Provide enough copper area around power MOSFETs
to help heat dissipation. Using thick copper also
reduces the trace resistance and inductance to have
better performance.
` The output capacitors should be placed physically close
to the load. This can minimize the trace parasitic
components and improve transient response.
` The feedback voltage divider resistor must be placed
close to FB pin because it is noise-sensitive.
` ROCSET should be placed close to IC.
` The small signal MOSFET/BJT used to shutdown the
controller should be placed close to IC to minimize the
trace parasitic components.
` Voltage feedback path must away from switching
nodes. The switching nodes, such as the
interconnection between high side MOSFET, low side
MOSFET and inductor, is extremely noisy. Feedback
path must away from this kind of noisy node to avoid
noise pick-up.
` A multi-layer PCB design is recommended. Use one
single layer as the ground and have separate layers for
power rail or signal.
DS8105-03 April 2011
RT8105
www.richtek.com
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