MC35XS3400 Datasheet, PDF (24/45 Pages) Freescale Semiconductor, Inc – Quad High Side Switch (Quad 35mΩ)

FUNCTIONAL DEVICE OPERATION
PROTECTION AND DIAGNOSTIC FEATURES
PROTECTION AND DIAGNOSTIC FEATURES
PROTECTIONS
Over-temperature Fault
The 35XS3400 incorporates over-temperature detection
and shutdown circuitry for each output structure.
Two cases need to be considered when the output
temperature is higher than T_SD:
•If the output command is ON: the corresponding output is
latched OFF. FS will be also latched to logic [0]. To
delatch the fault and be able to turn ON again the
outputs, the failure condition must disappear and the
autoretry circuitry must be active or the corresponding
output must be commanded OFF and then ON (toggling
fault_control signal of corresponding output) or
V_SUPPLY(POR) condition if V_DD = 0.
•If the output command is OFF: FS will go to logic [0] until
the corresponding output temperature will be below
T_SD.
For both cases, the fault register OT[0:3] bit into the status
register will be set to [1]. The fault bits will be cleared in the
status register after a SPI read command.
Over-current Fault
The 35XS3400 incorporates output shutdown in order to
protect each output structure against resistive short-circuit
condition. This protection is composed by eight predefined
current levels (time dependent) to fit 28W bulb profiles.
In the first turn-on, the lamp filament is cold and the current
will be huge. fault_control signal transition from logic [0] to [1]
or an autoretry define this event. In this case, the over-current
protection will be fitted to inrush current, as shown in
Figure 5. This over-current protection is programmable:
OC[1:0] bits select over-current slope speed and OCHI1
current step can be removed in case the OCHI bit is set to [1].
levels are available: OCLO1 or OCLO3 or OCLO4 based on
the state of the OCLO[1,0] bits.
If the load current level ever reaches the over-current
detection level, the corresponding output will latch the output
OFF and FS will be also latched to logic [0]. To delatch the
fault and be able to turn ON again the corresponding output,
the failure condition must disappear and the autoretry
circuitry must be active or the corresponding output must be
commanded OFF and then ON (toggling fault_control signal
of corresponding output) or V_SUPPLY(POR) condition if
V_DD = 0.
The SPI fault report (OC[0:3] bits) is removed after a read
operation.
In Normal mode using the internal PWM module, the
35XS3400 also incorporates a cooling bulb filament
management, if the OC_mode is set to logic [1]. In this case,
the 1^st step of multi-step over-current protection will depend
to the previous OFF duration, as illustrated in Figure 6. The
following figure illustrates the current level will be used in
function to the duration of previous OFF state (toff). The slope
of cooling bulb emulator is configurable with OCOFFCB[1:0]
bits.
Depending on toff
depending to toff
Over-current thresholds
Cooling
toff
h^fas^uo^ln^t_s^cig^onⁿa^trl ^ol
Over-current thresholds
h_Ps_Wo_Mn
h^fas^uo^ln^t_s^cig^onⁿa^trl ^ol
P^hW^soMⁿ
In steady state, the wire harness will be protected by
OCLO2 current level by default. Three other DC over-current
Severe Short-Circuit Fault
The 35XS3400 provides output shutdown in order to
protect each output in case of severe short-circuit during of
the output switching.
If the short-circuit impedance is below R_SHORT, the device
will latch the output OFF, FS will go to logic [0] and the fault
register SC[0:3] bit will be set to [1]. To delatch the fault and
be able to turn ON again the outputs, the failure condition
must disappear and the corresponding output must be
commanded OFF, and then ON (toggling fault_control signal
of corresponding output) or V_SUPPLY(POR) condition, if
V_DD = 0.
35XS3400
24
Analog Integrated Circuit Device Data
Freescale Semiconductor