A3941KLP-T ALLEGRO [Allegro MicroSystems], A3941KLP-T Datasheet - Page 12

• Manufacturer Part Number: A3941KLP-T
• Description: Automotive Full Bridge MOSFET Driver
• Manufacturer: ALLEGRO [Allegro MicroSystems]

A3941
tions, the output from the comparators are ignored under two
conditions:
▪ while the external FET is off, and
▪ until the end of the period, referred to as the fault blank time,
When the FET is turned on, if the drain-source voltage exceeds
the voltage at the VDSTH pin at any time after the fault blank
time, then a short fault will be detected. This fault will be latched
and the FET disabled until reset.
In applications where short detection is not required, this feature
may be disabled by connecting VDSTH to V5 or by applying a
voltage greater than the disable threshold voltage, V
completely disables the V
tion of short faults and any indication of short faults by the fault
flags. In this condition the external FETs will not be protected by
the A3941.
Short to Supply
voltage, V
tions to the battery or VBB connection is detected by monitoring
the voltage across the low-side FETs in each phase, using the
appropriate Sx pin and the LSS pin. This drain-source voltage,
V
after the FET is turned on.
DS
, is continuously compared to the voltage on the VDSTH pin.
DSDIS
, a short from any of the motor phase connec-
When V
DSTH
DS
monitor circuits, preventing detec-
is less than the disable threshold
Automotive Full Bridge MOSFET Driver
DSDIS
. This
The result of this comparison is ignored if the FET is not active.
It also is ignored for one fault blank time interval after the FET is
turned on. If, when the comparator is not being ignored, its output
indicates that V
FF2 will be high.
Short to Ground
old voltage, V
nections to ground is detected by monitoring the voltage across
the high-side FETs in each phase, using the appropriate Sx pin
and the voltage at VDRAIN. This drain-source voltage, V
continuously compared to the voltage on the VDSTH pin. The
result of this comparison is ignored if the FET is not active. It
also is ignored for one fault blank time interval after the FET is
turned on. If, when the comparator is not being ignored, its output
indicates that V
will be high.
Shorted Load
circuits will also detect a short across a motor phase winding. In
most cases, a shorted winding will be indicated by a high-side
and low-side fault being detected at the same time. In some cases
the relative impedances may permit only one of the shorts to be
detected.
DSDIS
The short-to-ground and short-to-supply monitor
DS
DS
When VDSTH is less than the disable thresh-
exceeds the voltage at the VDSTH pin, then
exceeds the voltage at the VDSTH pin, FF2
, a short from any of the motor phase con-
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
DS
, is
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