l6706 STMicroelectronics, l6706 Datasheet - Page 24

• Manufacturer Part Number: l6706
• Description: Vr11.1 Single Phase Controller With Integrated Driver
• Manufacturer: STMicroelectronics

Output current monitoring (IMON)
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Output current monitoring (IMON)
The device sources from IMON pin a current proportional to the load current (the sourced
current is a copy of droop current).
Connect IMON pin through a R
load indicator, as shown in
As INTEL VR11.1 specification required, on the IMON voltage as to be added a small
positive offset to avoid under-estimation of the output load (due to elements accuracy).
The voltage across IMON pin is given by the following formula:
where:
The IMON pin voltage is clamped to 1.100 V max to preserve the CPU from excessive
voltages as INTEL VR11.1 specification required.
Figure 9.
Current sense element (DCR inductor) has a non-negligible temperature variation. As a
consequence, the sensed current is subjected to a measurement error that causes the
monitoring voltage to vary accordingly.
To recover from this temperature related error, NTC resistor can be added into monitoring
network, as shown in
The monitoring voltage is then driven by the following relationship (neglecting the offset term
for simplicity):
where now the R
temperature through NTC resistor.
Considering the relationships between I
Output monitoring connection (left) and thermal compensation (right)
V
MONITORING
+3V3
V
IMON
To GND_core
(Remote Sense)
MONITORING
To CPU
R
IMON_OS
Figure 9.
is the equivalent monitoring resistor and it depends on the
=
Figure
R
----------------------------------- I
R
R
IMON
Doc ID 15698 Rev 1
IMON
=
IMON
IMON
----------------------------------- I
R
IMON
R
9.
I
IMON
DROOP
IMON
I
+
DROOP
⋅
resistor to remote ground (GND Core) to implement a
R
R
OS
OS
+
DROOP
⋅
C
R
R
IMON
⋅
OS
OS
=
DROOP
DCR
------------ - I
⋅
Rg
and the I
DROOP
+3V3
⋅
=
To GND_core
(Remote Sense)
OUT
To CPU
----------------------------------- DCR
R
R
R
+
IMON_OS
IMON
IMON
OUT
V
REF
, the voltage results:
+
⋅
R
⋅
R
NTC
R3
-----------------------------------
R
OS
OS
IMON
⋅
R
IMON
------------ - I
R2
R1
OS
Rg
I
DROOP
+
R
IMON
R
OS
⋅
OUT
C
IMON
L6706