nx2116 Microsemi Corporation, nx2116 Datasheet - Page 10

• Manufacturer Part Number: nx2116
• Description: Synchronous Pwm Controller With Current Limit, Power Good & Over Voltage
• Manufacturer: Microsemi Corporation

Case 2:
capacitors, typical design example of type III
compensator in which the crossover frequency is
selected as F
as the following steps. Here two SANYO MV-WG1500
with 13 m
and ESR zero F
Rev. 3.0
03/14/06
Figure 5 - Bode plot of Type III compensator
1. Calculate the location of LC double pole F
F
F
ESR
If electrolytic capacitors are used as output
LC
loop gain
power stage
compensator
F
is chosen as output capacitor.
2.9kHz
2
8.2kHz
2
2
2
LC
F
LC
Z1
<F
<F
ESR
(F
F
ESR
ESR
Z2
LC
ESR C
.
6.5m
F
F
<F
<F
1uH 3000uF
ESR
<F
1
L
LC
1
OUT
O
F
ESR
1
1
O
P1
40dB/decade
and F
<F
OUT
C
3000uF
F
O
OUT
O
)
O
<=1/10~1/5F
20dB/decade
F
P2
s
is shown
NX2116/2116A/2116B/2117/2117A
LC
double pole by equation (11).
half the switching frequency.
R =
R =
4
R
2. Set R
Choose R
3. Set zero F
4. Calculate C
Choose C
5. Calculate R
Choose R
6. Calculate R
Choose R
5. Calculate C
C
Choose C
6. Calculate C
Choose C
C =
C
1
=
=26.9k
3
2
1
3
1.5V 2
V
12V
=
=3.5nF
V
V
R
OSC
OUT
in
5.9k
2
2
2
2
2
2
2nF
2
2
20pF
2
-V
2
V
1
2
equal to 10k
REF
1
3
4
2
1
3
REF
1
=22pF.
=8k
=3.3nF.
=26.7k .
=2.2nF.
10k
R
=5.9k .
8.2kHz 3.3nF
0.75 2.9kHz 26.7k
1
F
1
F
R
1
ESR
26.7k
P1
2
Z2
Z1
4
3
3
4
2
1
6.5m
1
F
= F
60kHz 1uH 10k
by equation (14) with pole F
.
.
with F
with zero F
10k
(
O
C
R
F
1.8V-0.8V
F
1
P2
1
3
z2
4
LC
(
L R
1
2.9kHz 8.2kHz
-
and F
O
300kHz
F
=60kHz.
1
R
p1
1
0.8V
2
2
)
z1
p1
R
R
-
at 75% of the LC
=F
3
3
10k
8k
ESR
1
.
5.9k
)
5.9k
p2
at
10