L6714 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
L6714
STMicroelectronics
'L6714' PDF : 70 Pages View PDF
Tolerance band (TOB) definition
L6714
23.2
Ext. current sense circuit tolerance
(TOB CurrSense - Inductor Sense)
It can be further sliced as follow:
● Inductor DCR Tolerance (kDCR). Variations in the inductor DCR impacts on the output
voltage since the device reads a current that is different from the real current flowing
into the sense element. As a results, the controller will source a IDROOP current different
from the nominal. The results will be an AVP different from the nominal in the same
percentage as the DCR is different from the nominal. Since all the sense elements
results to be in parallel, the error related to the inductor DCR has to be divided by the
number of phases (N).
● Trans-conductance resistors tolerance (kRg). Variations in the Rg resistors impacts in
the current reading circuit gain and so impacts on the output voltage. The results will be
an AVP different from the nominal in the same percentage as the Rg is different from
the nominal. Since all the sense elements results to be in parallel, and so the three
current reading circuits, the error related to the Rg resistors has to be divided by the
number of phases (N).
● NTC Initial Accuracy (kNTC_0). Variations in the NTC nominal value at room
temperature used for the thermal compensation impacts on the AVP in the same
percentage as before. In addition, the benefit of the division by the number of phases N
cannot be applied in this case.
● NTC Temperature Accuracy (kNTC). NTC variations from room to hot also impacts on
the output voltage positioning. The impact is bigger as big is the temperature variation
from room to hot (∆T).
● All these parameters impacts the AVP, so they must be weighted on the maximum
voltage swing from zero load up to the maximum electrical current (VAVP). Total error
from external current sense circuit results:
TOBCurrSense =
VA2 VP ⋅
-k---D2---C----R--
N
+
k----R2---g-
N
+
kN2 TC0
+
⎛
⎝
-α----⋅------∆--D--T---C--⋅--R----k---N----T---C--⎠⎞
2
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