nx2116 Microsemi Corporation, nx2116 Datasheet - Page 9

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

order. The crossover frequency has to be selected as
F
and ESR zero F
Rev. 3.0
03/14/06
Case 1:
LC
Figure 4 - Bode plot of Type III compensator
<F
Design example for type III compensator are in
1.Calculate the location of LC double pole F
2. Set R
R =
O
F
F
<F
ESR
1
LC
loop gain
power stage
compensator
ESR,
V
R
OUT
7.6kHz
2
2
F
2
F
60.3kHz
2
2
and F
2
Z1
LC
equal to 20k .
-V
V
<F
ESR
F
REF
REF
Z2
F
O
.
O
<F
LC
ESR C
6m
<=1/10~1/5F
1uH 440uF
L
1
ESR
1
OUT
1
1
40dB/decade
20k
1.8V-0.8V
F
O
440uF
C
20dB/decade
OUT
F
OUT
F
P1
ESR
0.8V
s.
F
P2
16k
NX2116/2116A/2116B/2117/2117A
LC
frequency at 1/10~ 1/5 of the switching frequency. Set
F
double pole by equation (11).
half the switching frequency.
O
=50kHz.
4. Calculate R
R
Choose R
3. Set zero F
Choose C
5. Calculate C
C
Choose C
6. Calculate C
Choose C
7. Calculate R
Choose R
C =
C
R =
2
3
3
1
=
=916pF
4
=
=17.2k
2
2
2.64k
2
2
1.6nF
1.5V
2
2
V
12V
2
30pF
2
V
OSC
in
1
1
1
1
2
3
3
R
20k
=33pF
=16k
=1nF, R
=1.5nF.
=2.61k
0.75 7.6kHz 17.4k
60.3kHz 1nF
2
1
F
1
R
1
F
17.4k
2
2
Z2
P1
Z1
4
4
3
2
1
(
and C
1
= F
by equation (14) with pole F
by equation (13).
with zero F
F
1
F
z2
R
C
(
C
1
P2
7.6kHz 60.3kHz
4
4
LC
-
3
3
F
50kHz 1uH
=17.4k
1
F
O
1nF
3
1
and F
p1
1
300kHz
with the crossover
)
L
-
z1
p1
C
at 75% of the LC
out
=F
1
ESR
440uF
.
)
p2
at
9