VND810P-E Application information
Doc ID 17606 Rev 2 19/28
Recommended values are:
R
prot
= 10 kΩ
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 +5 V 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 Section 2.3: Electrical
characteristics.
Figure 25. Open-load detection in off-state
V
OL
V batt. V
PU
R
PU
R
L
R
DRIVER
+
LOGIC
+
-
INPUT
STATUS
V
CC
OUT
GROUND
I
L(off2)
