nx2141 Microsemi Corporation, nx2141 Datasheet - Page 14

• Manufacturer Part Number: nx2141
• Description: Single Channel Mobile Pwm Controller With Feedforward And Enable
• Manufacturer: Microsemi Corporation

ESR POSCAP, OSCON)
which the crossover frequency is selected as
F
steps.
and ESR zero F
Rev. 1.6
05/15/07
LC
Case 1:
<F
Typical design example of type III compensator in
1. Calculate the location of LC double pole F
O
F
Figure 18 - Bode plot of Type III compensator
F
<F
ESR
LC
loop gain
power stage
compensator
ESR
7.59kHz
2
2
60.3kHz
F
and F
2
2
F
Z1
LC
ESR
(F
<F
F
LC
Z2
.
O
F
O
ESR C
6m
<F
<F
<1/10 is shown as the following
LC
1uH 440uF
L
1
1
OUT
ESR
O
1
1
<F
40dB/decade
(for most ceramic or low
ESR
F
440uF
C
O
OUT
)
20dB/decade
OUT
F
F
P1
ESR
F
P2
LC
double pole by equation (11).
one third of the switching frequency.
15kHz.
at the LC double pole.
5. Calculate C
2. Set R
3. Calculate C
C
Choose C
4. Calculate C
Choose C
Choose C
6. Calculate R
R
Choose R
7. Calculate R
Choose R
R
C
C =
3
2
1
2
3
=
=1.7nF
1.2k
2
10
2
8.35k
V
2
11nF
2
2
2
1
2
959pF
2
V
OSC
IN
4
equal to 2.5k
1
2
1
3
3
2
2
=15nF.
=1nF.
=2.2nF.
60.3kHz 2.2nF
1
1
F
=1.5k .
=10k .
0.75 7.59kHz 2.5k
2.2nF
1
F
1
R
P1
C
3
2
2.5k
Z1
with the crossover frequency F
3
4
1
2
3
2
1
by equation (14) with pole F
with zero F
by equation (13) with F
C
by setting compensator zero F
R
15kHz 1uH 440uF
F
(
1
3
F
P2
4
1
Z2
F
1
(
O
7.59kHz
R
66.7kHz
2.5k
4
F
L C
1
P1
1
)
z1
at 75% of the LC
OUT
60.3kHz
NX2141
1
p1
=F
)
p2
ESR
O
at
at
.
Z2
14