Datasheet

2
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1
2
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15.1
1
EN
stopIN
EN
EN
OFFTHEN
stopIN
EN
hysEN
R
V
V
R
R
V
V
R
R -
÷
÷
ø
ö
ç
ç
è
æ
-
=-
÷
÷
ø
ö
ç
ç
è
æ
-
=
÷
÷
ø
ö
ç
ç
è
æ
+
+´=
÷
÷
ø
ö
ç
ç
è
æ
+
+´=
hysENEN
EN
hysENEN
EN
OFFTHENstopIN
RR
R
V
RR
R
VV
_2
1
_2
1
___
115.11
÷
÷
ø
ö
ç
ç
è
æ
-
=
÷
÷
ø
ö
ç
ç
è
æ
-
=
1
2.1
1
_
1
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_
1
2
V
V
R
V
V
R
R
startupIN
EN
ONTHEN
startupIN
EN
EN
÷
÷
ø
ö
ç
ç
è
æ
-´=
÷
÷
ø
ö
ç
ç
è
æ
-´= 1
2.1
1
_
2
__
_
21
V
V
R
V
V
RR
sta rtupIN
EN
O NT HE N
sta rtupIN
ENEN
÷
÷
ø
ö
ç
ç
è
æ
+´=
÷
÷
ø
ö
ç
ç
è
æ
+´=
2
1
2
1
___
12.11
EN
EN
EN
EN
ONTHENstartupIN
R
R
V
R
R
VV
V
IN
V
TH_EN
ON/SD
V
1.2V
REF
EN
EN_hys
GND
VIN
EN
Comparator
R
EN1
R
EN2
R
EN HYS
TPS62125
SLVSAQ5C –MARCH 2012–REVISED DECEMBER 2013 www.ti.com
ENABLE THRESHOLD AND HYSTERESIS SETTING
Figure 53. Using the Enable Comparator Threshold and Hysteresis for an input SVS (supply voltage
supervisor)
The enable comparator can be used as an adjustable input supply voltage supervisor (SVS) to start and stop the
DC/DC converter depending on the input voltage level. The input voltage level, V
IN_startup
, at which the device
starts up is set by the resistors R
EN1
and R
EN2
and can be calculated by :
(6)
The resistor values R
EN1
and R
EN2
can be calculated by:
(7)
(8)
The input voltage level V
IN_stop
at which the device will stop operation is set by R
EN1
, R
EN2
and R
EN HYS
and can
be calculated by:
(9)
The resistor value R
EN_hys
can be calculated according to:
(10)
The current through the resistors R
EN1
, R
EN2
and R
EN HYS
should be higher than 1µA. In applications operating
over the full temperature range and in noisy environments, the resistor values can be reduced to smaller values.
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