nx2113 Microsemi Corporation, nx2113 Datasheet - Page 12

• Manufacturer Part Number: nx2113
• Description: 300khz & 600khz Synchronous Pwm Controller With Programmable Bus Uvlo
• Manufacturer: Microsemi Corporation

order. Use the same power stage requirement as demo
board. The crossover frequency has to be selected as
F
and ESR zero F
Rev. 2.0
11/18/05
LC
Figure 10 - Bode plot of Type III compensator
<F
1.Calculate the location of LC double pole F
2.Set R
3. Set zero F
4. Calculate R
Design example for type III compensator are in
O
F
F
<F
ESR
LC
loop gain
power stage
compensator
ESR,
7kHz
2
2
60kHz
2
F
2
2
and F
equal to10k
Z1
ESR
F
Z2
Z2
.
4
F
O
0.78uH 660uF
L
ESR C
and C
4m
<=1/10~1/5F
LC
= F
1
OUT
1
1
1
LC
40dB/decade
3
C
and F
F
with the crossover frequency
OUT
660uF
O
OUT
then R
20dB/decade
F
F
P1
p1
ESR
s.
=F
1
F
= 10k
ESR
P2
.
LC
smaller than 1/10~ 1/5 of the switching frequency. Set
F
double pole by equation (11).
half the swithing frequency.
O
=45kHz.
Choose C
5. Calculate C
Choose C
6. Calculate C
Choose C
7. Calculate R
R
Choose R
C
C =
C
R =
3
2
3
1
4
=
=2nF
=
=11k
1.2k
2
2
12V
2
V
2
2
2V
2
2.75nF
48pF
V
2
2
OSC
in
1
2
1
3
3
1
=47pF.
=2.2nF, R
=2.7nF.
=1.2k
2
R
10k
60kHz 2.2nF
2
1
F
R
0.75 7kHz 11k
1
11k
P1
2
1
F
1
3
4
Z1
2
1
by equation (14) with pole F
by equation (13).
C
(
with zero F
C
1
F
45kHz 0.78uH
3
F
F
1
3
z2
R
O
P2
(
2.2nF
1
4
7kHz 60kHz
4
-
=11k
300kHz
NX2113/2113A
L
F
1
1
p1
C
)
-
out
z1
1
at 75% of the LC
660uF
)
p2
at
12