CS5155H
Applications Information: continued
4. Connect the ground terminals of the Compensation
capacitor directly to the ground of the fast feedback filter
capacitor to prevent common mode noise from effecting
the PWM comparator.
5. Place the output filter capacitor(s) as close to the load as
possible and connect the ground terminal to pin 14 (LGnd).
6. To implement adaptive voltage positioning, connect
both slow and fast feedback pins 16 (V
FB
) and 8 (V
FFB
) to
the regulator output right at the inductor terminal. Connect
inductor to the output capacitors via a trace with the fol-
lowing resistance:
R
TRACE
=
80mV
I
MAX
7. If DC regulation is to be optimized (at the expense of
degraded transient regulation), adaptive voltage position-
ing can be disabled by connecting to V
FB
pin directly to the
load with a separate trace (remote sense).
8. Place 5V input capacitors close to the switching MOSFET
and synchronous MOSFET.
Route gate drive signals V
GATE(H)
(pin 10) and V
GATE(L)
(pin 12 when used) with traces that are a minimum of 0.025
inches wide.
V
CC
0.1µF
15
To the negative terminal of the
input capacitors
11
1.0µF
V
COMP
100pF
V
FFB
This causes the output voltage to be +40mV with no load,
and -40mV with a full load, improving regulator transient
response. This trace must be wide enough to carry the full
output current. (Typical trace is 1.0 inch long, 0.17 inch
wide). Care should be taken to minimize any additional
losses after the feedback connection point to maximize reg-
ulation.
8
5
SOFTSTART
OFF TIME
To the negative terminal of the output capacitors
Figure 20: Layout Guidelines
Additional Application Circuits
5V
12V
MBRS
120
0.1µF
MBRS120
1µF
V
CC1
V
ID0
V
ID1
V
ID2
V
ID3
V
ID4
C
OFF
330pF
SS
0.1µF
0.33µF
COMP
LGnd
V
FB
V
FFB
3.3k
+
V
CC2
V
GATE(H)
MBRS120
1µF
Si4410DY
3µH
3.3V/10A
+
100µF/10V x 3
Tantalum
3.3V
1µF
+
Si9410
V
CC1
V
ID0
V
ID1
V
ID2
Si9410DY
33µF/25V x 3
Tantalum
V
CC2
V
GATE(H)
5µH
2.5V/7A
V
FB
CS5155H
V
GATE(L)
PGnd
V
ID3
V
ID4
C
OFF
330pF
SS
0.1µF
0.33µF
CS5155H
V
GATE(L)
Si9410
+
100µF/10V x 2
Tantalum
PGnd
LGnd
V
FFB
3.3k
COMP
100pF
100µF/10V x 3
Tantalum
100pF
Figure 21: 5V to 3.3V/10A converter.
Figure 23: 3.3V to 2.5V/7A converter with 12V bias.
12V
5V
1N5818
+12V
MBRS
120
0.1µF
MBRS120
1µF
V
CC1
V
ID0
V
ID1
V
ID2
V
ID3
V
ID4
MBRS120
1µF
Si4410
V
CC2
V
GATE(H)
3µH
+
100µF/10V x 3
Tantalum
1µF
1N5818
22Ω
1/4W
1µF
Remote
Sense
3.3V/10A
1N4746
18V 1W
0.1µF
FY10AAJ-
03
+
820µF/16V
×
4
Aluminum
Electrolytic
1.1µH
3.3V/5A
V
CC1
V
ID0
V
CC2
V
GATE(H)
CS5155H
V
FB
10Ω
Si9410
+
100µF/10V x 3
Tantalum
V
ID1
V
ID2
V
ID3
V
ID4
C
OFF
330pF
CS5155H
V
FB
FY10AAJ-
03
FY10AAJ-
03
+
V
GATE(L)
1200µF/10V
×
2
Aluminum
Electrolytic
C
OFF
330pF
SS
0.1µF
0.33µF
COMP
LGnd
PGnd
V
FFB
3.3k
Connect to
other circuits for
current sharing
V
GATE(L)
SS
0.1µF
0.33µF
COMP
LGnd
100pF
PGnd
V
FFB
3.3k
100pF
Figure 22: 5V to 3.3V/10A converter with current sharing.
Figure 24: 12V to 3.3V/5A converter with remote sense.
13
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
