PM6680 STMicroelectronics, PM6680 Datasheet - Page 38

• Manufacturer Part Number: PM6680
• Description: IC CTRLR DUAL STEP DOWN 32VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6680

• Applications: Controller, Notebook Power System
• Voltage - Input: 6 ~ 28 V
• Number Of Outputs: 2
• Voltage - Output: 0.9 ~ 5.5 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• Output Voltage: 5 V, 0.9 V to 5.5 V, 0.9 V to 3.3 V
• Output Current: 0.33 A
• Input Voltage: 5.5 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 10 C
• 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

Device description
38/49
In order to reduce ground noise due to load transient on the other section, it is
recommended to add a resistor R
low pass filter (see
times) than the switching frequency of the section:
Equation 26
Due to the capacitive divider (C
Equation 27
Where V
If the ripple is very small (lower than approximately 30 mV), a further compensation network,
named virtual ESR network, is needed. This additional part generates a triangular ripple
that is added to the ESR output voltage ripple at the input of the integrator network. The
complete control schematic is represented in
Figure 37. Virtual ESR network
? V
? V
RIPPLEout
OUTPUT
OUTPUT
VOLTAGE
VOLTAGE
D
D
D
D
? V
? V
t
t
1
1
is the output ripple and q is the attenuation factor of the output ripple.
Figure 36
R1
R1
R1
R1
V
C
C
C
C
RIPPLE
T NODE
T NODE
VOLTAGE
VOLTAGE
L
L
L
L
T
T
INT
R
R
R
R
). The cutoff frequency f
R
=
t
t
INT
INT
V
INT
RIPPLEout
, C
R
R
R
R
C
C
C
C
COMP PIN
COMP PIN
VOLTAGE
VOLTAGE
R
R
R
R
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
=
filt
and a capacitor C
C
C
INT
INT
C
C
INT
INT
2
Vr
Vr
), the ripple voltage at the COMP pin is given by:
FILT
FILT
FILT
FILT
π
×
×
f
CUT
t
t
C
Figure 37
INT
? V
? V
C
C
C
C
C
×
INT
INT
INT
INT
1
INT
C
+
C
1
1
R
R
R
R
R
R
R
R
R
R
R
R
INT
INT
C
2
2
2
2
2
2
1
1
1
1
1
1
COMP
COMP
COMP
COMP
CUT
filt
OUT
OUT
OUT
OUT
×
FB
FB
+
FB
FB
filt
.
=
C
C
must be much greater (10 or more
that, together with C
V
filt
filt
RIPPLEout
Vr
Vr
Vr
Vr
gm
gm
gm
gm
+
+
×
V1
V1
V1
V1
q
Vr
Vr
Vr
Vr
Comparator
Comparator
Comparator
Comparator
+
+
-
-
PWM
PWM
PWM
PWM
INT
, realize a
PM6680