EVALPM6680A STMicroelectronics, EVALPM6680A Datasheet - Page 35

• Manufacturer Part Number: EVALPM6680A
• Description: EVAL BOARD FOR PM6680A
• Manufacturer: STMicroelectronics

Specifications of EVALPM6680A

• Mfg Application Notes: PM6680A, AN2565 Appl Note
• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 3, Non-Isolated
• Power - Output: 10.5W
• Voltage - Output: 1.8V, 3.3V, 5V
• Current - Output: 2.5A, 2.5A, 100mA
• Voltage - Input: 6 ~ 36V
• Regulator Topology: Buck
• Frequency - Switching: 200kHz, 300kHz
• Board Type: Fully Populated
• Utilized Ic / Part: PM6680A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6263

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
35/48