l6712a STMicroelectronics, l6712a Datasheet - Page 9

• Manufacturer Part Number: l6712a
• Description: Two-phase Interleaved Dc/dc Controller
• Manufacturer: STMicroelectronics

The device offers a bi-directional pin REF_IN/OUT: the internal reference used for the regulation is usually
available on this pin with 3mA of maximum current capability except when VID code 111 is programmed;
in this case the device accepts an external reference through the REF_IN/OUT pin and regulates on it.
When external reference is used, it must range from 0.800V up to 3.300V to assure proper functionality of
the device.
Figure 2 shows a block schematic of how the Reference for the regulation is managed when internal or
external reference is used.
The voltage identification (VID) pin configuration or the external reference provided also sets the power-
good thresholds (PGOOD) and the Over/Under voltage protection (OVP/UVP) thresholds.
Figure 2. Reference Management
The output regulated voltage accuracy can be extracted from the following relationships (worst case con-
dition):
where V
tively and K
tion (see relevant section).
A statistical analysis could consider applying the root-sum-square (RSS) method to calculate the precision
since all the variables are statistically independent as follow:
V
O UT _TOT_ACC
OS_RA
REF_IN/OUT
V
OS
O UT _TOT_ACC
VID3
VID2
VID1
= 1+1/RA_Gain reflects the impact of the Remote Amplifier Gain (RA_Gain) on the regula-
and V
=
[ ]
%
EXT_REF_Accuracy[%]
OS_EA
=
EXT_REF_Accuracy[%]
V
[ ]
O UT _TOT_ACC
%
REFERENCE
are the offsets related to the Error Amplifier and the Remote Amplifier respec-
BAND-GAP
(1.235V)
=
DAC
V
OUT_ACC
(worst case with external reference)
(worst case with internal reference)
[%]
(with internal reference)
[ ]
=
%
+
± (
(
+
SOFT-START
2.0%
V
+
CONTROL
K
OUT _ACC
DIGITAL
------------------------------------ - [%]
REF_IN/OUT
LOGIC
O S
)
V
⋅
+
V
-------------------- 100
PRO G
V
§
©
O S_RA
-------------------------- - 100
EXT_REF
OUT
± (
[%]
5mV
)
2
⋅
+
)
§
©
K
VIDx
+
⋅
O S
=
§
©
-------------------------- - 100
EXT_REF
V
± (
⋅
V
·
¹
PROG
V
-------------------- 100
O S_EA
0.9%
V
+
O S_RA
OUT
K
O S
) K
+
⋅
⋅
⋅
± (
-------------------- - 100
O S
V
INTERNAL REFERENCE
EXTERNAL REFERENCE
8mV
FB
o ut
·
¹
·
¹
AMPLIFIER
⋅
2
+
± (
-------------------- - 100
ERROR
K
)
V
8mV
⋅
O S
OUT
⋅
L6712A L6712
V
-------------------- 100=
)
V
⋅
O S_RA
OUT
COMP
⋅
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