33874 Datasheet, PDF (30/37 Pages) Freescale Semiconductor, Inc – Quad High-Side Switch (Quad 35 mΩ)

TYPICAL APPLICATION
DIAGNOSIS WITHOUT MCU
When any fault appears (over current, open load…), a full
diagnosis can be reported via the SPI. Without an MCU, the
fault status pin allows reduced diagnosis, as illustrated in
table 3.
Table 3. Diagnosis without SPI
IN[x] level
HS[x] level
FS level
Latched
Normal operation
H
H
H
L
L
H
Over temperature
L
L
L
H
L
L
Under voltage
L
L
L
H
L
L
Over voltage
L
L
H
H
L
L
Over current
L
L
H
H
L
L
Short circuit to VPWR
L
H
L
H
H
H
Open load
L
Z
L
H
H
H
H : High Level, L : Low Level, Z : High impedance, potential depends on the external circuit
N/A
YES
YES
NO
YES
NO
NO
We can note that it is not possible to distinguish over
temperature, over current, under voltage, and over voltage.
Nevertheless, Open load and short circuit to V_PWR fault can
be singled out. All protections are reported to Fault status pin
(FS), Open load and short circuit to V_PWR are reported only if
the Output is OFF. If the fault is latched, the output must be
turned OFF then ON to disable the fault.
CONCLUSION
Although the MC33874 is not fully functional without a
microcontroller to control and program it, standalone
functioning is safe because all protections are available.
Diagnosis is limited, but the fault status pin will report any
malfunction.
This is a good way to evaluate the main electrical
MC33874 features. Some simplified applications can also
use the MC33874 switch without an MCU to drive a high
power load with full protection.
33874
30
Analog Integrated Circuit Device Data
Freescale Semiconductor