PM6680A STMicroelectronics, PM6680A Datasheet - Page 35

• Manufacturer Part Number: PM6680A
• Description: IC CTLR DUAL SYNC STDN 5X5VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6680A

• Applications: Controller, Embedded Computer System
• Voltage - Input: 6 ~ 36 V
• Number Of Outputs: 2
• Voltage - Output: 0.9 ~ 5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• For Use With: 497-6379 - BOARD EVALUATION FOR PM6680A497-6378 - BOARD EVALUATION FOR PM6680497-6425 - BOARD EVAL BASED ON PM6680A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PM6680A
9.6
Closing the integrator loop
The design of external feedback network depends on the output voltage ripple. If the ripple
is higher than approximately 30 mV, the feedback network (
keep the loop stable.
Figure 36. Circuitry for output ripple compensation
The stability of the system depends firstly on the output capacitor zero frequency.
The following condition should be satisfied:
Equation 23
where k is a design parameter greater than 3 and Rout is the ESR of the output capacitor. It
determinates the minimum integrator capacitor value C
Equation 24
where gm = 50 µs is the integrator transconductance.
OUTPUT
VOLTAGE
Vr
t
COMP PIN
VOLTAGE
D
D
∆
? V
L
L
t
∆
C
C
R
R
? V
C
f
sw
O
O
INT
O
O
U
C
C
U
U
U
>
T
T
T
T
F
F
>
C
R
C
R
k
I
I
L
L
×
I
I
2
I
I
T
T
N
N
N
N
π
f
T
T
T
T
Zout
×
⎛
⎜ ⎜
⎝
f
=
sw
g
k
V
V
m
2
C
C
R
R
C
R
R
C
−
π
O
I
O
I
N
N
2
1
f
2
1
×
O
O
Zout
T
T
M
C
M
U
U
out
F
F
P
k
P
⎞
⎟ ⎟
⎠
T
T
B
B
×
×
INT
V
R
I=gm(V1-Vr)
Vr
OUT
out
:
Figure 36
V
V
r
r
g
g
m
m
+
V
V
1
1
V
V
) is usually enough to
r
r
Design guidelines
+
C
C
-
o
o
m
m
P
P
W
p
W
p
a
a
M
M
r
r
a
a
t
t
o
o
r
r
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