Datasheet

MAX15036/MAX15037
Boost Converter Compensation
The boost converter compensation gets complicated
due to the presence of a right-half-plane zero f
ZERO,RHP
.
The right-half-plane zero causes a drop in-phase while
adding positive (+1) slope to the gain curve. It is impor-
tant to drop the gain significantly below unity before the
RHP frequency. Use the following procedure to calculate
the compensation components. (See Figure 4.)
1) Calculate the LC double-pole frequency, f
LC
, and
the right half plane zero frequency.
where:
Target the unity-gain crossover frequency for:
2) Place a zero at 0.75 x f
LC
.
where R
F
≥ 10kΩ.
3) Calculate C
A
for a target crossover frequency, f
C
:
where ω
C
= 2π f
C.
4) Place a pole at f
ZERO,RHP
.
5) Place the second zero at f
LC
.
6) Place the second pole at 1/2
the switching frequency.
Improving Noise Immunity
When using the MAX15036/MAX15037 in noisy environ-
ments, adjust the controller’s compensation to improve
the system’s noise immunity. In particular, high-fre-
quency noise coupled into the feedback loop causes
duty-cycle jitter. One solution is to lower the crossover
frequency (see the Compensation section).
PCB Layout Guidelines
Careful PCB layout is critical to achieve low-switching
power losses and clean stable operation. Use a multi-
layer board whenever possible for better noise immuni-
ty. Follow these guidelines for good PCB layout:
1) Solder the exposed pad to a large copper plane
under the IC. To effectively use this copper area as
a heat exchanger between the PCB and the ambi-
ent, expose this copper area on the top and bottom
C
C
fRC
CF
F
SW F F
=
×× ××
−
(.
)
205
1
π
()f
RC
P
FCF
2
1
2
=
××π
R
fC
R
LC A
A
1
1
2
=
××
−
π
()f
RC
Z
A
2
1
21
=
××π
R
fRC
A
ZERO HP A
=
××
1
2π ,
()f
RC
P
AA
1
1
2
=
××π
C
VDLC
RV
A
OSC C OUT
CFIN
=
−
()
+
⎡
⎣
⎤
⎦
1
2
2
ω
ω
C
fR
F
LC F
=
×××
1
2075π .
()f
RC
Z
FF
1
1
2
=
××π
f
f
C
ZERO RHP
≤
,
5
D
V
V
R
V
I
IN
OUT
MIN
OUT
OUT MAX
=−
=
1
()
()
f
D
LC
f
DR
L
LC
OUT
ZERO RHP
MIN
=
−
×
=
−
×
1
2
1
2
2
π
π
,
()
()
2.2MHz, 3A Buck or Boost Converters
with an Integrated High-Side Switch
20 ______________________________________________________________________________________