Datasheet

VN5E025AJ-E Application information
Doc ID 13106 Rev 5 27/37
3.4.1 Short to V
CC
and OFF state open load detection
Short to V
CC
A short circuit between V
CC
and output is indicated by the relevant current sense pin set to
V
SENSEH
during the device off state. Small or no current is delivered by the current sense
during the on state depending on the nature of the short circuit.
OFF state open load with external circuitry
Detection of an open load in off mode requires an external pull-up resistor R
PU
connecting
the output to a positive supply voltage V
PU
.
It is preferable V
PU
to be switched off during the module stand-by mode in order to avoid the
overall stand-by current consumption to increase in normal conditions, i.e. when load is
connected.
An external pull down resistor R
PD
connected between output and GND is mandatory to
avoid misdetection in case of floating outputs in off state (see Figure 33: Current sense and
diagnostic).
R
PD
must be selected in order to ensure V
OUT
< V
OLmin
unless pulled up by the external
circuitry:
R
PD
≤ 22 K Ω is recommended.
For proper open load detection in off state, the external pull-up resistor must be selected
according to the following formula:
For the values of V
OLmin
,V
OLmax
, I
L(off2)r
and I
L(off2)f
see Table 10: Openload detection
(8V<V
CC
<18V).
VVIRV
OLfoffLPD
OFFupPull
OUT
2
min)2(
_
=<⋅=
−
VV
RR
IRRVR
V
OL
PDPU
roffLPDPUPUPD
ONupPull
OUT
4
max
)2(
_
=>
+
⋅⋅−⋅
=
−