Datasheet

Brown Out Protection
0
150
VINS VINS _ V
I I= ´
(120)
150 0 1 15m m= ´ =
VINS
I . A A
(121)
75
AC( on )
V V=
(122)
65
AC ( off )
V V=
(123)
1
2
AC( on ) F _ BRIDGE ENABLE _ th(max)
VINS
VINS
V V VINS
R
I
´ - -
=
(124)
1
2 75 0 95 1 6
6 9
15
VINS
V . V . V
R . M
Am
´ - -
= = W
(125)
1
2
2
ENABLE _ th(max) VINS
VINS
AC( on ) ENABLE _ th(max) F _ BRIDGE
VINS R
R
V VINS V
´
=
´ - -
(126)
2
1 6 6 5
100
2 75 1 6 0 95
VINS
. V . M
R k
V . V . V
´ W
= = W
´ - -
(127)
UCC28019A
www.ti.com .................................................................................................................................................. SLUS828B – DECEMBER 2008 – REVISED APRIL 2009
Select the top divider resistor into the VINS pin so as not to contribute excessive power loss. The extremely low
bias current into VINS means the value of R
VINS1
could be hundreds of megaOhms. For practical purposes, a
value less than 10 M Ω is usually chosen. Assuming approximately 150 times the input bias current through the
resistor dividers will result in an R
VINS1
that is less than 10 M Ω , so as to not contribute excessive noise, and still
maintain minimal power loss. The brown out protection will turn off the gate drive when the input falls below the
user programmable minimum voltage, V
AC(off)
, and turn on when the input rises above V
AC(on)
.
A 6.5-M resistance is chosen.
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