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2.3.8
VINS pin setting
The minimum operation input voltage needs to be specified for LLC resonant converter with the Vins pin.
The typical circuit of mains input voltage sense and process is shown Figure 6.
Figure 6
Mains input voltage sense
The mains input voltage is divided by
connected between VINS and Ground, an adjustable hysteresis between the on and off input voltage can
be created as
=
*
V
I
R
hys
hys
INSH
Assuming the turn-on bus voltage
typically.The
and
R
INSH
−
V
V
=
INon
INoff
R
INSH
I
INS
V
R
=
=
th
INSH
R
−
INSL
V
V
inoff
th
A standard resistor value for
The blanking time for leaving brown-out is around 500μs and for entering brown-out is around 50μs.
Please note that the calculation above is based on typical specification values of the IC.
2.3.9
Latch off function and burst mode selection
Internally, the EnA pin has a pull-up current source of 100μA. By connecting a resistor outside from this
pin to ground, certain voltage level is set up on this pin. If the voltage level on this pin is pulled down
below certain level during operation, IC is latched. If the external resistor has a negative temperature
coefficient, this pin can be used to implement over- temperature protection (OTP). In this design,
selected at 1MΩ to set the pin voltage to be 2V level and no OTP is designed.
Application Note
and
R
INSH
is 380V typically and the turn-off bus voltage
V
INon
can be calculated as:
R
INSL
−
380
320
=
=
Ω
6
M
−
6
10
*
10
6
. 1
25
*
6
*
10
=
23
5 .
k
−
320
. 1
25
is 24kΩ.
R
INSL
. With the internal current source
R
INSL
Ω
15
is
I
hys
[24]
is 320V
V
INoff
[25]
[26]
is
R
EnA
2011-07-06
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