L6714 STMicroelectronics, L6714 Datasheet - Page 58

• Manufacturer Part Number: L6714
• Description: IC CTRLR 4PH W/DRIVERS 64-TQFP
• Manufacturer: STMicroelectronics

Specifications of L6714

• Applications: Controller, Intel VR10, VR11, AMD CPU
• Voltage - Input: 12V
• Number Of Outputs: 4
• Voltage - Output: 0.3 ~ 1.6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 64-TQFP Exposed Pad, 64-eTQFP, 64-HTQFP, 64-VQFP
• Mounting Style: SMD/SMT
• Case: QFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

System control loop compensation
58/70
Where:
●
●
●
●
●
●
●
Removing the dependence from the Error Amplifier gain, so assuming this gain high
enough, and with further simplifications, the control loop gain results:
The system Control Loop gain
to minimize static error and to cross the 0dB axes with a constant -20dB/dec slope with the
desired crossover frequency
zero and two poles; both the poles are fixed once the output filter is designed (LC filter
resonance
Figure 23. Equivalent control loop block diagram (left) and bode diagram (right).
To obtain the desired shape an R
implementation. A zero at
integrator minimizes the static error while placing the zero
C resonance assures a simple -20dB/dec shape of the gain.
In fact, considering the usual value for the output filter, the LC resonance results to be at
frequency lower than the above reported zero.
DROOP
Z
F
(s)
G
R
selected;
function;
Z
and the applied load R
Z
Z
A(s) is the error amplifier gain;
amplitude and has a typical value of 4V.
LOOP
Z
PWM
R
P
F
L
FB
SENSE
(s) is the parallel of the N inductor impedance;
FB
(s) is the compensation network impedance;
(s) is the impedance resulting by the parallel of the output capacitor (and its ESR)
(s)
DROOP
s
VID
R
=
LC
R
is the MOSFET R
FB
=
F
4
-- -
5
) and the zero (
–
=
4
-- -
5
COMP
C
R
---------------------
F
------------------ -
--------------------- -
SENSE
V
Rg
V
V
V IN
V
VSEN
OSC
OSC
OUT
IN
PWM
is the PWM transfer function where V
Z F s
---------------
R
R
O
F
FB
FB
;
= 1/R
REMOTE BUFFER
d V
T
dsON
(See Figure
64k
. Neglecting the effect of Z
ESR
OUT
is the equivalent output resistance determined by the droop
R O
------------------------------------------- -
F
F
) is fixed by ESR and the Droop resistance.
- C
L / N
R
C
or the Inductor DCR depending on the sensing element
+
64k
64k
O
R DROOP
F
F
+
is then introduced together with an integrator. This
R
-------
series network is considered for the Z
N
C
L
ESR
O
FBG
FBR
23) is designed in order to obtain a high DC gain
V
OUT
------------------------------------------------------------------------------------------------------------------------------------------------------------ -
s
2
R
C O
O
1
---- -
N
L
R
+
F
s
[dB]
+
K
F
s
(s), the transfer function has one
C
dB
F
O
--------------------- -
N
in correspondence with the L-
L
R
OSC
LC
R
DROOP
O
=
G
+
F
LOOP
C O
ESR
is the oscillator ramp
(s)
//R
ESR
O
+
ESR
+
F
C O
(s)
Z
F
(s)
R
-------
N
L
L6714
T
+
1