Datasheet

Example 2:
Setup12A tostartupintoan80Wloadand
chargea1600uFatnotmorethan17 A nominal.
ThendroptoanoperationalI
LIMIT
of8.25 A +/-
10%.
I
STARTUP
=17 A
First,thecorrectR
SET
mustbefoundtoset
maximumI
LIMIT
tolessthan17 A.
R
SET
=(I
LIMIT
xR
SENSE
xR
SUM
)/0.675
= 857 ! " (closest1%value= 845 ! )
Where;
R
SUM
=6810 ! "
R
SENSE
=5m!
NowI
LIMIT
=0.675R
SET
/(R
SUM
R
SENSE
)=16.75 A
Neglectingcurrentslewtime,thiswillchargethe
1600uFcapacitorin1.9ms.
IfR0[3:0]aresetto0101and R6 [4]=1the
current limitwilldropto50%oftheprogrammed
maximumafterdroppingoutofcurrentlimit
followinginrush. Theoperationalcurrentlimitis
now;
I
LIMIT
=0.5xI
INRUSH
=0.5x16.75=8.38 A
Thenew8.38 A currentlimitiswithinthespecof
8.25 A +/- 10%.
Note - Thesecalculationsuseallnominalvalues.
TPS2359
www.ti.com SLUS792H –FEBRUARY 2008–REVISED MAY 2013
Figure 26. Inrush Current Limiting Example 2
Table 15. Configuring 12-V Current Limits in Non-Redundant Systems
I
LIMIT
C
BULK
CHARGE TIME
I
LIMIT
- INRUSH 12VNRS FAULT TIME (ms)
OPERATIO (ms)
12xCLx
R
SET
NAL P
LOAD
(W)
[3:0]
12VNRS =
R6[4]=0 R6[4]=1 800 μF 1600 μF 800 μF 1600 μF
1
412 1111 8.17 8.17 8.17 80 6.4 12.8 8.5 17
698 111 13.84 8.3 8.3 80 1.34 2.68 2 3.5
845 101 16.75 8.38 8.38 80 0.95 1.9 1.5 3
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