L6728A STMicroelectronics, L6728A Datasheet - Page 15

• Manufacturer Part Number: L6728A
• Description: Voltage Mode PWM Controllers Hi-Freq. singl-phase PWM controller w/Po
• Manufacturer: STMicroelectronics

Specifications of L6728A

• Number Of Outputs: Dual Output
• Topology: Buck
• Output Voltage: 0.8 V
• Output Current: 1500 mA
• Switching Frequency: 660 KHz
• Duty Cycle (max): 67 %
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Package / Case: VFDFPN-10 EP
• Synchronous Pin: No
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L6728A
Figure 6.
●
●
To place the poles and zeroes of the compensation network, the following suggestions may
be followed:
Open loop converter singularities:
a)
b)
Compensation network singularities frequencies:
a)
b)
c)
d)
a)
Set the gain R
according to the approximated formula (suggested values for R
some kΩ):
F
F
F
F
F
F
----------
R
R
LC
ESR
Z1
Z2
P1
P2
FB
F
Example of type III compensation
=
=
=
=
=
=
compensation
converter gain
open loop
loop gain
=
EA gain
closed
------------------------------
2π R
---------------------------------------------------- -
2π
open loop
--------------------------------- -
2π L C
------------------------------------------------- -
2π R
------------------------------ -
2π R
F
------------
F
------------------------------------------- -
2π C
gain
0dB
LC
⋅
⋅
⋅
⋅
(
⋅
1
R
Gain
1
[dB]
0dB
F
⋅
1
F
S
⋅
FB
ΔV
------------------ -
OUT
⋅
⋅
⋅
F
C
1
⎛
⎝
C
V
OUT
1
1
/R
+
-------------------- -
C
C
OSC
F
IN
S
F
R
FB
F
⋅
+
ESR
S
⋅
) C
C
C
in order to obtain the desired closed loop regulator bandwidth
⋅
P
P
⎞
⎠
S
F
Z1
F
F
LC
Z2
F
F
ESR
P1
F
0dB
F
P2
20log (R
F
/R
20log (V
FB
Log (Freq)
)
IN
Application details
FB
/ΔV
OSC
is in the range of
)
15/32