Datasheet

Application information VND5E050K-E
24/40 Doc ID 14472 Rev 4
3.4 Open-load detection in off-state
Off-state open-load detection requires an external pull-up resistor (R
PU
) connected between
output pin and a positive supply voltage (V
PU
) like the +5V line used to supply the
microprocessor.
The external resistor has to be selected according to the following requirements:
1. no false open-load indication when load is connected: in this case we have to avoid
V
OUT
to be higher than V
Olmin
; this results in the following condition
V
OUT
=(V
PU
/(R
L
+R
PU
))R
L
<V
Olmin
.
2. no misdetection when load is disconnected: in this case the V
OUT
has to be higher than
V
OLmax
; this results in the following condition R
PU
<(V
PU
–V
OLmax
)/I
L(off2)
.
Because I
s(OFF)
may significantly increase if V
out
is pulled high (up to several mA), the pull-
up resistor R
PU
should be connected to a supply that is switched OFF when the module is in
standby.
The values of V
OLmin
, V
OLmax
and I
L(off2)
are available in the Electrical Characteristics
section.
Figure 33. Open-load detection in off-state
VOL
V batt. VPU
R
PU
RL
R
DRIVER
+
LOGIC
+
-
INPUT
STATUS
V
CC
OUT
GROUND
I
L(off2)