FUNCTIONAL DEVICE OPERATION
PROTECTION AND DIAGNOSTIC FEATURES
GROUND (GND) DISCONNECT PROTECTION
V
V
DD
PWR
If the DC motor module ground is disconnected from load
ground, the device protects itself and safely turns OFF the
output regardless of the output state at the time of
disconnection. A 10k resistor needs to be added between the
EN pin and the rest of the circuitry in order to ensure the
device turns off in case of ground disconnect and to prevent
exceeding this pin’s maximum ratings.
33981
MCU
No current
GND OUT
FAULT REPORTING
Diode
This 33981 indicates the faults below as they occur by
driving the FS pin to logic [0]:
V
M
PWR
10.0 kΩ
• Overtemperature fault
• Overcurrent fault on OUT
• Overload fault on the external low-side MOSFET
The FS pin will return to logic [1] when the over
temperature fault condition is removed. The two other faults
are latched.
Figure 11. Reverse Battery Protection
Table 6. Functional Truth Table in Fault Mode
Conditions
CONF INHS INLS OUT
GLS
FS
EN
TEMP CSNS OCLS
Comments
The 33981 is currently in fault mode.
The OUT is OFF. TEMP at 0 V
indicates this fault. Once the fault is
removed 33981 recovers its normal
mode.
Overtemperature
on OUT
x
x
x
L
x
x
x
x
L
L
L
x
H
L
x
L
H
L
L
x
x
x
x
L
x
x
x
x
L
The 33981 is currently in fault mode.
The OUT is OFF and GLS is at 0 V.
TEMP at 0 V indicates this fault. Once
the fault is removed 33981 recovers its
normal mode.
Overtemperature
on GLS
L
L
L
H
H
H
The 33981 is currently in fault mode.
The OUT is OFF. It is reset by a
logic [0] at INHS for at least tRST(diag)
When INHS goes to 0 V, CSNS goes to
5.0 V.
Overcurrent
on OUT
H
L
L
H
.
The 33981 is currently in fault mode.
GLS is at 0 V and OCLS internal
current source is off. The external
resistance connected between OCLS
and GND pin will pull OCLS pin to 0 V.
The fault is reset by a logic [0] at INLS
Overload
on External Low-
Side MOSFET
L
for at least tRST(diag)
.
H = High level
L = Low level
x = Don’t care
33981
Analog Integrated Circuit Device Data
Freescale Semiconductor
15
FREESCALE [ Freescale ]
