Texas Instruments LM3445 Evaluation Board LM3445-230VFLBK/NOPB LM3445-230VFLBK/NOPB データシート
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製品コード
LM3445-230VFLBK/NOPB
V
LED(MIN)
1 -
I
D
=
V
BUCK(MAX)
x I
LED(AVE)
t
V
AC-RMS(MAX)
2
V
D
SNVS570L – JANUARY 2009 – REVISED MAY 2013
RE-CIRCULATING DIODE
The LM3445 Buck converter requires a re-circulating diode D10 (see the
circuit to carry the
inductor current during the MOSFET Q2 off-time. The most efficient choice for D10 is a diode with a low forward
drop and near-zero reverse recovery time that can withstand a reverse voltage of the maximum voltage seen at
V
drop and near-zero reverse recovery time that can withstand a reverse voltage of the maximum voltage seen at
V
BUCK
. For a common 110V
AC
± 20% line, the reverse voltage could be as high as 190V.
(33)
The current rating must be at least:
I
D
= 1 - (D
MIN
) x I
LED(AVE)
(34)
Or:
(35)
Copyright © 2009–2013, Texas Instruments Incorporated
27
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