eup3409 Eutech Microelectronics Inc, eup3409 Datasheet - Page 9

• Manufacturer Part Number: eup3409
• Description: Dual 1.5mhz, 800ma Synchronous Step-down Converter
• Manufacturer: Eutech Microelectronics Inc

Thermal Considerations
To avoid the EUP3409 from exceeding the maximum
junction temperature, the user will need to do a thermal
analysis. The goal of the thermal analysis is to determine
whether the operating conditions exceed the maximum
junction temperature of the part. The temperature rise is
given by:
Where P
the regulator ; θ
junction of the die to the ambient temperature.
The junction temperature, T
Where T
T
of 125°C.
DS3409 Ver1.0 Jan. 2008
J
should be below the maximum junction temperature
T
T
A
R
D
J
=T
=(P
=I
is the ambient temperature.
LOAD
A
D
+T
)(θ
R
2
JA
JA
× R
)
is the thermal resistance from the
DS(ON)
J
, is given by:
is the power dissipated by
9
PC Board Layout Checklist
When laying out the printed circuit board, the following
guidelines should be used to ensure proper operation of
the EUP3409.
1. The input capacitor C
2. The power traces, consisting of the GND trace, the
3. The FBx pin should connect directly to the feedback
4. Keep the switching node, SWX, away from the
closely as possible. This capacitor provides the AC
current to the internal power MOSFETs.
SW trace and the V
direct and wide.
resistors. The resistive divider R11/R12 and
R21/R22 must be connected between the C
ground.
sensitive FBx node.
INX
INX
trace should be kept short,
EUP3409
should connect to V
OUTX
INX
and
as