PM6680ATR STMicroelectronics, PM6680ATR Datasheet - Page 36

• Manufacturer Part Number: PM6680ATR
• Description: IC CTRLR DUAL STEP DOWN 32VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6680ATR

• 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
• Other names: 497-6896-2; PM6680ATR

Design guidelines
36/48
In order to ensure stability it must be also verified that:
Equation 25
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 figure 13). The cutoff frequency f
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
RIPPLEout
is the output ripple and q is the attenuation factor of the output ripple.
V
RIPPLE
INT
=
R
INT
V
INT
INT
C
, C
RIPPLEout
INT
=
filt
and a capacitor C
2
), the ripple voltage at the COMP pin is given by:
>
π
2
×
π
×
f
CUT
g
×
C
m
Figure 37
f
Zout
INT
×
C
1
C
INT
C
+
×
INT
INT
C
V
CUT
filt
Vr
OUT
×
+
filt
.
C
C
=
must be much greater (10 or more
that, together with C
filt
filt
V
RIPPLEout
×
q
INT
, realize a
PM6680A