NX2141CMTR MICROSEMI [Microsemi Corporation], NX2141CMTR Datasheet - Page 15

• Manufacturer Part Number: NX2141CMTR
• Description: SINGLE CHANNEL MOBILE PWM CONTROLLER WITH FEEDFORWARD AND ENABLE
• Manufacturer: MICROSEMI [Microsemi Corporation]

Case 2:
capacitors, typical design example of type III
compensator in which the crossover frequency is
selected as F
the following steps. Here two SANYO MV-WF1000 with
18 m is chosen as output capacitor, output inductor is
2.2uH, output voltage is 1.05V, switching frequency is
200kHz.
and ESR zero F
Rev. 1.6
05/15/07
Figure 19- Bode plot of Type III compensator
8. Calculate R
Choose R
1. Calculate the location of LC double pole F
R =
F
loop gain
If electrolytic capacitors are used as output
power stage
compensator
LC
1
V
R
F
F
2.4kHz
2
OUT
2
Z1
LC
2
LC
<F
F
1
-V
<F
V
=32k
ESR
(F
Z2
F
ESR
F
REF
REF
ESR
ESR
LC
LC
.
1
L
2.2uH 2000uF
<F
<F
F
1
.
OUT
<F
P1
O
40dB/decade
1
ESR
(for electrolytic capacitors)
O
10k
1.05V-0.8V
<F
F
and F
C
O
OUT
O
)
20dB/decade
O
0.8V
<1/10F
F
P2
s
32k
is shown as
LC
double pole by equation (11).
one third of the switching frequency.
15kHz.
at the LC double pole.
5. Calculate R
2. Set R
3. Calculate C
C
Choose C
4. Calculate C
Choose C
Choose R
6. Calculate C
C
Choose C
7. Calculate R
F
R =
C
ESR
3
2
1
3
=10
=1.08k
14nF
V
2
2
2
V
2
35nF
2
959pF
2
OSC
IN
8.8kHz
2
2
4
2
equal to 2.5k
2
1
3
3
=33nF.
9mohm 2.5k
=1nF.
=1.2k .
8.8kHz 1.2k
=15nF.
2
1
F
0.75 2.4kHz 2.5k
1
R
3
1
F
2.5k
ESR R
P1
Z1
with the crossover frequency F
ESR C
9m
4
2
1
3
2
1
by equation (14) with pole F
15kHz 1uH
with zero F
by equation (13) with F
1
by setting compensator zero F
R
F
R
1
1
F
P2
3
O
4
1
66.7kHz
2000uF
4
L
OUT
z1
at 75% of the LC
NX2141
p1
=F
p2
ESR
O
at
at
.
15
Z2