STEVAL-ISA027V1 STMicroelectronics, STEVAL-ISA027V1 Datasheet - Page 17

• Manufacturer Part Number: STEVAL-ISA027V1
• Description: BOARD EVAL 1PH STPDN CONV L6726A
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of STEVAL-ISA027V1

• Design Resources: STEVAL-ISA027V1 Gerber Files STEVAL-ISA027V1 Schematic STEVAL-ISA027V1 Bill of Material
• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.25V
• Current - Output: 20A
• Voltage - Input: 5 ~ 12V
• Regulator Topology: Buck
• Frequency - Switching: 270kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6726A
• Input Voltage: 5 V to 12 V
• Output Voltage: 1.25 V
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: L6726A
• Other names: 497-6259

L6726A
Type II compensation relies on the zero introduced by the output capacitors bank to achieve
stability. Thus, a needed condition to successfully apply type II compensation is
(usually true when output capacitor is based on electrolytic, aluminium electrolytic or
tantalum capacitor).
To define compensation network components values, the below suggestions may be
followed:
a)
b)
c)
d)
e)
f)
Set the output resistor divider in order to obtain the desired output voltage:
Usual values of R
(consider trade-off between power dissipation on output resistor divider and offset
introduced by FB bias current).
If the desired output voltage is equal to internal reference, R
FB pin can be directly connected to V
Set R
the approximated formula:
If V
Place F
Place F
Check that compensation network gain is lower than open loop transconductance
EA gain.
Estimate phase margin obtained (it should be greater than 45°) and repeat,
modifying parameters, if necessary.
C
OUT
R
F
---------- -
R
R
C
F
F
OS
FB
=
P
in order to obtain the desired closed loop regulator bandwidth according to
Z
P
= V
=
=
-------------------------------- -
2π R
below F
at 0.5
=
F
------------------------------ -
----------------------------------------------------
π R
REF
0dB
⋅
V
-------------- 1
V
⋅
OUT
REF
F
5
F
, just consider (R
⋅
·
2
LC
F
⋅
F
F
⋅
F
LC
SW
ESR
FB
–
C
LC
C
F
(typically 0.2
:
F
and R
Doc ID 12754 Rev 4
⋅
⋅
F
ΔV
------------------ -
SW
V
OSC
IN
–
OS
1
≅
⋅
ranges from some hundreds of Ω to some kΩ
------- -
gm
------------------------------ -
π R
FB
1
·
⋅
F
+R
⋅
LC
R
----------------------------
F
1
OS
FB
⋅
):
OUT
F
R
SW
)/R
+
OS
.
R
OS
OS
factor equal to 1.
OS
Application details
has to be NC and
F
ESR
<
F
17/35
0dB