L6918D View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
L6918D Datasheet PDF : 35 Pages
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L6918 L6918A
FB and COMP has always a capacitor in series (See fig. 8). The voltage regulated by each device is then equal
to:
VOUT = VID – RFB ⋅ IFB = VID – RFB ⋅ R-----S---R-E---Ng----S---E-- ⋅ IOUT
Where IOUT is the output current of each device (equal to the total load current ILOAD divided by the number of
devices N)
Since IFB depends on the current information about the two phases of each device, the output characteristic vs.
load current is given by:
VOUT = VID – RFB ⋅ IOUT = VID – RFB ⋅ -R----S--R-E----Ng----S---E-- ⋅ IOUT = VID – RFB ⋅ -R----S--R--E---gN----S---E-- ⋅ -I-L---O--2--A----D--
Where ROUT is the equivalent output resistance due to the droop function and IOUT is still the output current of
each device (that is the total current delivered to the load ILOAD divided by 2.
Figure 7. Output transient response without (a) and with (b) the droop function
ESR DROP
ESR DROP
VNOM
VMAX
VMIN
VDROOP
(a)
Figure 8. Active Droop Function Circuit
COMP
(b)
VDROOP
RFB
FB
To VOUT
Total Cu rrent Info (IINFO1+IINFO2)
Ref
The feedback current is equal to 50µA at nominal full load (IFB = IINFO1 + IINFO2) and 70µA at the OCP interven-
tion threshold, so the maximum output voltage deviation is equal to:
∆VFULL _POSITIVE_LOAD = +RFB ⋅ 50µ A
∆VO L_INTERVENTION = +RFB ⋅ 70µA
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