L6712ADTR STMicroelectronics, L6712ADTR Datasheet - Page 21

• Manufacturer Part Number: L6712ADTR
• Description: IC CTRLR DC/DC 2PH SYNC 28SOIC
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L6712ADTR

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.9 ~ 3.3 V
• Current - Output: 2A
• Frequency - Switching: 150kHz
• Voltage - Input: 12V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (7.5mm Width)
• Power - Output: 2W
• Operating Temperature Range: - 40 C to + 125 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-4218-2

Where ∆I
For R
and R
3.12.2Average Current Mode (ACM) Control Loop (DROOP=FB)
The average current mode control loop is reported in Figure 18. The current information I
the DROOP pin flows into R
The ACM control loop gain results (obtained opening the loop after the COMP pin):
Where:
■
■
■
■
■
■
■
Removing the dependence from the Error Amplifier gain, so assuming this gain high enough, the control
loop gain results:
Considering now that in the application of interest it can be assumed that R
R
DROOP
Z
load Ro;
Z
Z
A(s) is the error amplifier gain;
and has a typical value of 3V
RA_Gain is the Remote Amplifier Gain.
G
R
PWM
P
F
L
DROOP
LOOP
(s) is the parallel of the two inductor impedance;
(s) is the compensation network impedance;
(s) is the impedance resulting by the parallel of the output capacitor (and its ESR) and the applied
SENSE
SENSE
<<R
=
READ
s ( )
= 4mΩ and I
4
-- -
5
o
mismatches.
=
, it results:
⋅
=
------------------ -
∆V
is the difference between one phase current and the ideal current (I
Rsense
--------------------- - R
–
V
4
-- -
5
Rg
G
OSC
IN
⋅
LOOP
------------------ -
∆V
G
V
LOOP
is the ACM PWM transfer function where ∆V
OSC
MAX
⋅
IN
s ( )
FB
FB
= 40A the current sharing error is equal to 2.5%, neglecting errors due to Rg
⋅
s ( )
=
Z
-------------- -
implementing the dependence of the output voltage from the read current.
is the equivalent output resistance determined by the droop function;
R
F
–
FB
s ( )
=
4
-- -
5
⋅
–
------------------ -
∆V
⋅
PWM Z
----------------------------------------------------------------------------------------------------------------------- -
(
------------------------------------------------------------------------------------------------------------------------------------------ - RA_Gain
s
V
Z
2
OSC
P
IN
⋅
s ( )
Co
⋅
⋅
+
⋅
----------------------------------- -
Z
F
L
-- -
2
Z
P
s ( )
+
L
s ( )
1
s ( )
Z
s
+
⋅
F
⋅
(
+
s ( )
s Co
)
R
Z
⋅
---------------
2 Ro
⋅
DROOP
L
⋅
Z
-------------- -
L
s ( )
A s ( )
F
s ( )
⋅
⋅
⎛
⎝
+
------------------------ -
RA_Gain
⎛
⎜
⎝
R
------- -
Rg
+
Rs
+
Co ESR
DROOP
⎛
⎝
RA_Gain Z
1
+
⋅
+
RA_Gain Z
-------------------------------------------- -
OSC
----------- -
A s ( )
1
+
is the oscillator ramp amplitude
+
ESR
⎞ R
⎠
R
⋅
Co
⋅
FB
P
⋅
⎞
⎠
FB
⋅
s ( )
---------------
2 Ro
P
⋅
)
o
L
s ( )
>>R
MAX
⎞
⎟
⎠
/2).
L6712A L6712
DROOP
L
+
; ESR<<R
1
⋅
sourced by
o
21/29
and