STEVAL-ISA050V1 STMicroelectronics, STEVAL-ISA050V1 Datasheet - Page 38

• Manufacturer Part Number: STEVAL-ISA050V1
• Description: KIT EVAL PM6641 CHIPSET/DDR2/3
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of STEVAL-ISA050V1

• Main Purpose: Special Purpose DC/DC, DDR Memory Supply
• Outputs And Type: 4, Non-Isolated
• Power - Output: 14.7W
• Voltage - Output: 1.05V, 1.5V, 1.8V, 0.9V
• Current - Output: 4A, 2.8A, 2.5A, 2A
• Voltage - Input: 2.7 ~ 5.5V
• Regulator Topology: Buck
• Frequency - Switching: 750kHz
• Board Type: Fully Populated
• Utilized Ic / Part: PM6641
• Input Voltage: 2.7 V to 5.5 V
• Product: Power Management Modules
• Silicon Manufacturer: ST Micro
• Silicon Core Number: PM6641
• Kit Application Type: Power Management - Voltage Regulator
• Application Sub Type: Monolithic Voltage Regulator
• Kit Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PM6641
• Other names: 497-8425

Components selection
8.4
38/47
If ceramic capacitors are used, the output voltage ripple due to inductor current ripple is
negligible. Then the inductance could be smaller, reducing the size of the choke. In this case
it is important that output capacitor can adsorb the inductor energy without generating an
overvoltage condition when the system changes from a full load to a no load condition.
The minimum output capacitance can be chosen by the following equation:
Equation 21
where V
voltage before the load transient.
SW regulator compensation components selection
As described in section SW regulators control loop , the PM6641 switching regulators control
loop is:
Equation 22
If the output capacitor C
frequency zero,
Equation 23
This pole is useful if the f
However, the first assumption must relate the cross-over frequency, f
loop gain:
Equation 24
G
LOOP
f
(
is the output capacitor voltage after the load transient and V
2 j
π
G
f
CO
LOOP
)
f
≅
zo
(
g
) s
=
m
K
=
1
L
g
O
2
α
zo
m
π
and its equivalent series resistance (ESR) R
K
C
2
zero is greater than about
π
L
O
f
α
R
CO
Doc ID 13510 Rev 3
ES
sC
C
C
C
C
OUT
2
⎛
⎜
⎜
⎝
, the roll-off compensation pole must be added:
⋅
2
sC
π
f
PRO
(
π
f
sC
CO
,
f
min
Ro
CO
C
C
R
≅
C
R
=
C
C
O
R
C
2
L
+
π
(
C
R
+
⋅
Vf
C
I
C
ES
C
2
1
RO
1
LOAD
2
)
Ro
C
−
+
R
R
Vi
+
C
,
MAX
1
O
2
⎞
⎟
⎟
⎠
f
C
)
⋅
0
R
sC
5
O
(
O
=
.
sC
(
g
R
m
O
ES
K
R
L
ES
+
α
i
CO
R
is the output capacitor
2
+
ES
O
, with the control
π
1
f
)
)
CO
provide a low
+
1
C
R
R
O
O
C
(
R
R
ES
O
PM6641
+
R
O
)