MC33899VW FREESCALE [Freescale Semiconductor, Inc], MC33899VW Datasheet - Page 20

• Manufacturer Part Number: MC33899VW
• Description: Programmable H-Bridge Power IC
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

or short to GND latches the appropriate SPI fault bits until the
FLTCLR bit is set. Any additional faults that occur prior to
setting FLTCLR will be ignored.
Fault Detection During OFF State
is done during the OFF state, when either the EN1 or EN2 pin
is a logic [1], by analyzing the states of both the high side and
low side outputs interacting to the external load. S1 is pulled
up internally via a high-impedance pull-up to V
20
0.75 V
0.25 V
33899
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
Note SGFON and SBFON are ON-State Fault.
EN2
S1
S0
In the full or half H-Bridge mode an open, short to ignition,
Fault detection for both the high side and low side outputs
EN1
CC
CC
V
Figure 13. OFF-State Fault Detection Diagram
CC
12 kΩ
12 kΩ
(Reverse Polarity)
S0
S1
EN1
EN2
Load Current
t
FDO
OF
SGFON
SBFON
S0/S1 are at 2.5VDC,
Fault Timer Starts
Wake Up, Open
No SPI Bits Set
CC
, while S0 is
Timer
Fault
SBF
SGF
pulled down internally to ground. In a normal load state, the
low-impedance (relative to the internal pull-ups/pull-downs)
will force both load connections to about 0.5 V
compared with an internal reference of 0.75 V
while S0 is compared to an internal reference of 0.25V
nominally.
based on the combination of the outputs of these two
comparators.
time exceeding the OFF-state fault timer, the fault bit will be
latched into the SPI Fault register. The OFF-state fault timer
is started when either the EN1 or EN2 pin transitions from a
logic [1] to a logic [0] (both inputs previously logic [1]) or from
a logic [0] to a logic [1] (both inputs previously logic [0]). The
OFF-state filter time is substantially longer than the ON-state
to allow energy in the load to dissipate. False open state
faults may be set when the outputs are shut down and the
load current (reverse polarity only) takes more than the OFF-
state filter time to decay to zero. The microprocessor should
clear the open state fault SPI bit and read the Fault register
again under this condition.
Once any of the above faults are indicated for a period of
< 0.75 V
< 0.75 V
> 0.75 V
> 0.75 V
t
FDO
S1
CC
CC
CC
CC
Table 7
Table 7. OFF-State Fault Detection
Timer Starts
Open Fault
Current in Load < 0, Erroneous
> 0.25 V
< 0.25 V
< 0.25 V
> 0.25 V
indicates what status the load will be in
Open Fault SPI Bit Set
S0
Analog Integrated Circuit Device Data
CC
CC
CC
CC
Freescale Semiconductor
Short to Ground
Short to VIGNP
Goo Back
Load Status
Normal Load
to Sleep
Open Load
CC
CC
. S1 is
nominally,
CC