FAN5350_08 FAIRCHILD [Fairchild Semiconductor], FAN5350_08 Datasheet - Page 8

• Manufacturer Part Number: FAN5350_08
• Description: 3MHz, 600mA Step-Down DC-DC Converter in Chip-Scale and MLP Packaging
• Manufacturer: FAIRCHILD [Fairchild Semiconductor]

© 2007 Fairchild Semiconductor Corporation
FAN5350 Rev. 1.0.3
PCB Layout Guidelines
For the bill of materials of the FAN5350 evaluation
board, see Table 1. There are only three external
components: the inductor and the input and output
capacitors. For any buck switcher IC, including the
FAN5350, it is always important to place a low-ESR
input capacitor very close to the IC, as shown in Figure
7. That ensures good input decoupling, which helps
reduce the noise appearing at the output terminals and
Table 2. FAN5350 Evaluation Board Bill of Materials (optional parts are installed by request only)
Figure 7. The FAN5350 Evaluation Board PCB (CSP)
Inductor
Capacitor 4.7μF, ±10%, 6.3V, X5R, 0603
IC DC/DC Regulator in CSP, 5 bumps
Load Resistor (Optional)
Description
1.2μH, 1.8A, 55mΩ
1.3μH, 1.2A, 90mΩ
1.5μH, 1.3A
Qty.
1
1
2
1
8
C
R
IN
Ref.
ensures that the control sections of the IC do not
behave erratically due to excessive noise. This reduces
switching cycle jitter and ensures good overall
performance. It is not considered critical to place either
the inductor or the output capacitor very close to the IC.
There
components further away from the IC.
Feedback Loop
One key advantage of the non-linear architecture is that
there is no traditional feedback loop. The loop response
to changes in V
explains its extraordinary transient response. The
absence of a traditional, high-gain compensated linear
loop means that the FAN5350 is inherently stable over
a wide range of L
L
provided it is confirmed that the calculated peak current
for the required maximum load current is less than the
minimum
advantage is that this generally leads to improved
transient response, since a small inductance allows for
a much faster increase in current to cope with any
sudden load demand.
The inductor can be increased to 2.2µH; but, for the
same reason, the transient response gets slightly
degraded. In that case, increasing the output capacitor
to 10µF helps significantly.
U1
L1
,C
LOAD
OUT
OUT
can be reduced further for a given application,
is
of
some
the
Taiyo Yuden
OUT
OUT
MURATA
Vendor
Fairchild
TOKO
flexibility in
FDK
Any
is essentially instantaneous, which
and C
closed-loop
OUT
.
GRM39 X5R 475K 6.3
MIPSA2520D1R0
CBC3225T15MR
moving
current
Part Number
1117AS-1R2M
FAN5350UCX
www.fairchildsemi.com
these two
limit.
The