STEVAL-ISA039V1 STMicroelectronics, STEVAL-ISA039V1 Datasheet - Page 16

• Manufacturer Part Number: STEVAL-ISA039V1
• Description: BOARD EVAL BASED ON L6727
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of STEVAL-ISA039V1

• Design Resources: STEVAL-ISA039V1 Gerber Files L6727 Eval Board Schematic STEVAL-ISA039V1 Bill of Materials
• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.25V
• Current - Output: 5A
• Voltage - Input: 5 ~ 12V
• Regulator Topology: Buck
• Frequency - Switching: 300kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6727
• 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: L6727
• Other names: 497-8266

Application details
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Compensation goal is to close the control loop assuring high DC regulation accuracy, good
dynamic performances and stability. To achieve this, the overall loop needs high DC gain,
high bandwidth and good phase margin.
High DC gain is achieved giving an integrator shape to compensation network transfer
function. Loop bandwidth (F
stability, it should not exceed F
has to cross 0dB axis with -20 dB/decade slope.
As an example,
Figure 7.
●
●
Open loop converter singularities:
a)
b)
Compensation Network singularities frequencies:
a)
b)
c)
d)
F
F
F
F
F
F
ESR
Example of type III compensation.
LC
Z1
Z2
P1
P2
compensation
converter gain
loop gain
open loop
EA gain
=
Figure 7
closed
=
=
open loop
=
=
=
------------------------------
2π R
gain
--------------------------------- -
2π L C
---------------------------------------------------- -
2π
------------------------------------------------- -
2π R
------------------------------ -
2π R
------------------------------------------- -
2π C
⋅
Gain
[dB]
0dB
⋅
⋅
⋅
⋅
(
1
R
1
F
1
⋅
F
S
FB
shows an asymptotic bode plot of a type III compensation.
OUT
⋅
⋅
⋅
C
OUT
1
1
⎛
⎝
C
1
+
F
-------------------- -
C
0dB
C
S
⋅
R
F
F
ESR
SW
Doc ID 12933 Rev 4
+
S
⋅
) can be fixed choosing the right R
) C
C
C
⋅
/2π. To achieve a good phase margin, the control loop gain
P
P
⎞
⎠
F
Z1
S
F
F
LC
Z2
F
F
ESR
P1
F
0dB
F
P2
20log (R
F
/R
F
20log (V
/R
FB
Log (Freq)
)
FB
IN
ratio, however, for
/ΔV
OSC
)
L6727