max5072etjt Maxim Integrated Products, Inc., max5072etjt Datasheet - Page 24

• Manufacturer Part Number: max5072etjt
• Description: Max5072 2.2mhz, Dual-output Buck Or Boost Converter With Por And Power-fail Output
• Manufacturer: Maxim Integrated Products, Inc.

2.2MHz, Dual-Output Buck or Boost
Converter with POR and Power-Fail Output
Place a zero
where R
Calculate C
where ω
Place a pole
Place the second zero
Place the second pole
the switching frequency.
24
______________________________________________________________________________________
C
F
I
C
=
≥ 10kΩ.
= 2πf
C
I
V
CF
for a target crossover frequency, f
OSC
R
(
(
f
f
Z
I
C
P
C
1
1
=
=
R
F
.
⎡
⎢
⎢
⎣
=
1
=
f
(
(
2π
=
C
1
2
=
2
−
2
π
ω
2
≤
π
π
D
×
2
C
π
×
)
π
f
×
×
f
(
ZERO RHP
2
×
ZERO RHP
0 5
f
×
R
Z
×
R
.
(
1
+
0 75
2
1
f
F
R
I
P
f
.
ω
LC
F
2
f
1
5
×
1
=
×
SW
,
C
,
×
C
=
C
2
2
1
C
×
×
I
π
F
V
2
×
F
×
)
f
IN
C
)
LC
at f
×
π
L
R
I
×
O
R
×
F
1
−
at 0.75 x f
ZERO,RHP
C
×
1
R
×
×
R
I
R
×
F
C
1
I
C
F
C
O
×
F
I
⎤
⎥
⎥
⎦
)
C
)
−
CF
1
at f
.
LC
C
)
:
LC
.
at 1/2
.
In applications where the MAX5072 are subject to noisy
environments, adjust the controller’s compensation to
improve the system’s noise immunity. In particular,
high-frequency noise coupled into the feedback loop
causes jittery duty cycles. One solution is to lower the
crossover frequency (see the Compensation section).
Careful PC board layout is critical to achieve low
switching losses and clean, stable operation. This is
especially true for dual converters where one channel
can affect the other. Refer to the MAX5072 EV kit data
sheet for a specific layout example. Use a multilayer
board whenever possible for better noise immunity.
Follow these guidelines for good PC board layout:
1) For SGND, use a large copper plane under the IC
2) Isolate the power components and high-current
3) Keep the high-current paths short, especially at the
4) Connect SGND and PGND together close to the IC
5) Keep the power traces and load connections short.
6) Ensure that the feedback connection to C
7) Route high-speed switching nodes (BST_/VDD_,
and solder it to the exposed paddle. To effectively
use this copper area as a heat exchanger between
the PC board and ambient, expose this copper area
on the top and bottom side of the PC board. Do not
make a direct connection from the exposed pad
copper plane to SGND (pin 29) underneath the IC.
path from the sensitive analog circuitry. Use a sep-
arate PGND plane under the OUT1 and OUT2 sides
(referred to as PGND1 and PGND2). Connect the
PGND1 and PGND2 planes together at one point
near the IC.
ground terminals. This practice is essential for sta-
ble, jitter-free operation.
at the ground terminals of VL and V+ bypass capac-
itors. Do not connect them together anywhere else.
This practice is essential for high efficiency. Use
thick copper PC boards (2oz vs. 1oz) to enhance
full-load efficiency.
short and direct.
SOURCE_) away from the sensitive analog areas
(BYPASS, COMP_, and FB_). Use the internal PC
board layer for SGND as EMI shields to keep radiat-
ed noise away from the IC, feedback dividers, and
analog bypass capacitors.
PC Board Layout Guidelines
Improving Noise Immunity
OUT
is