L6711TR STMicroelectronics, L6711TR Datasheet - Page 41

• Manufacturer Part Number: L6711TR
• Description: IC CTRLR 3PHASE VID/DACS 48-TQFP
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L6711TR

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 0.8 ~ 1.55 V
• Current - Output: 2A
• Frequency - Switching: 150kHz
• Voltage - Input: 12V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFP Exposed Pad, 48-eTQFP, 48-HTQFP, 48-VQFP
• Power - Output: 2.5W
• Output Voltage: 0.8 V to 1.581 V
• Output Current: 95 A
• Input Voltage: 13.8 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-5363-2; L6711TR

L6711
17
System control loop compensation
The control loop is composed by the Current Sharing control loop and the Average Current
Mode control loop. Each loop gives, with a proper gain, the correction to the PWM in order
to minimize the error in its regulation: the Current Sharing control loop equalize the currents
in the inductors while the Average Current Mode control loop fixes the output voltage equal
to the reference programmed by VID.
control loop.
Figure 21. Main control loop diagram
The average current mode control loop is reported in
sourced by the FB pin flows into R
from the read current.
The system can be modeled with an equivalent single phase converter which only
difference is the equivalent inductor L/3 (where each phase has an L inductor).The ACM
control loop gain results (obtained opening the loop after the COMP pin):
Where:
G
LOOP
C O R R E C T I O N
D U T Y C Y C L E
C U R R E N T
S H A R I N G
I
IN F O 3
R
selected;
Z
and the applied load Ro;
Z
Z
A(s) is the error amplifier gain;
R
I
P
F
L
IN F O 2
SENSE
D ROOP
(s) is the parallel of the three inductor impedance;
(s) is the compensation network impedance;
(s) is the impedance resulting by the parallel of the output capacitor (and its ESR)
s
I
IN F O 1
=
–
is the mosfet R
-------------------------------------------------------------------------------------------------------------------
=
Z
P
1 / 5
1 / 5
1 / 5
R
--------------------- R
SEN SE
s
PWM Z
Rg
+
Z
L
s
F
FB
dsON
s
is the equivalent output resistance determined by droop;
Z
--------------
A s
F
R
or the Inductor DCR depending on the sensing element
s
D ROOP
4 /5
FB
C O M P
E R R O R A M P L I F I E R
+
implementing the dependence of the output voltage
⎛
Figure 21
P W M 1
P W M 2
P W M 3
1
+
+
----------- -
A s
Z
1
P
s
⎞
⎠
Z
F
( s )
shows the block diagram of the system
R
FB
Figure
System control loop compensation
V ID
F B
22. The current information I
L 1
L 2
L 3
R
F B
I
F B
C o
R o
41/50
FB