VN750-E / VN750S-E / VN750PT-E / VN750B5-E
V
OUT
=(V /(R +R ))R <V
PU L PU L Olmin.
OPEN LOAD DETECTION IN OFF STATE
2) no misdetection when load is disconnected: in this
case the V has to be higher than V ; this
OUT
OLmax
Off state open load detection requires an external pull-up
results in the following condition R <(V
V
)/
PU
PU– OLmax
resistor (R ) connected between OUTPUT pin and a
PU
I
.
L(off2)
positive supply voltage (V ) like the +5V line used to
PU
Because I
may significantly increase if V
is
s(OFF)
out
supply the microprocessor.
The external resistor has to be selected according to the
following requirements:
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.
1) no false open load indication when load is connected:
The values of V
, V
OLmin
and I
are available in
L(off2)
OLmax
in this case we have to avoid V
to be higher than
OUT
the Electrical Characteristics section.
V ; this results in the following condition
Olmin
Figure 9. Open Load detection in off state
V batt.
VPU
VCC
RPU
DRIVER
IL(off2)
INPUT
+
LOGIC
OUT
+
-
R
STATUS
VOL
RL
GROUND
10/31
STMICROELECTRONICS [ ST ]
