FUNCTIONAL DEVICE OPERATION
PROTECTION AND DIAGNOSTIC FEATURES
PROTECTION AND DIAGNOSTIC FEATURES
levels are available: OCLO1 or OCLO3 or OCLO4 based on
the state of the OCLO[1,0] bits.
PROTECTIONS
Over-temperature Fault
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 VSUPPLY(POR) condition if
VDD = 0.
The 10XS3412 incorporates over-temperature detection
and shutdown circuitry for each output structure.
Two cases need to be considered when the output
temperature is higher than TSD
:
• 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
VSUPPLY(POR) condition if VDD = 0.
The SPI fault report (OC[0:3] bits) is removed after a read
operation.
In Normal mode using internal PWM module, the
10XS3412 incorporates also a cooling bulb filament
management if OC_mode and Xenon are set to logic [1]. In
this case, the 1st 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.
• If the output command is OFF: FS will go to logic [0] till
the corresponding output temperature will be below
TSD
.
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
Depending on toff
depending to toff
The 10XS3412 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 Xenon-HID manners by
default or, 55 W or 28 W bulb profiles, selectable separately
by Xenon bit and 28 W bits (as illustrated Figure 13,
page 36).
Over-current thresholds
Cooling
toff
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 of OCHI bit is set to [1].
fault_control
hson signal
hson
PWM
Severe Short-circuit Fault
Over-current thresholds
The 10XS3412 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
, the device
SHORT
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 VSUPPLY(POR) condition if
VDD = 0.
fault_control
hson signal
hson
PWM
The SPI fault report (SC[0:3] bits) is removed after a read
operation.
In steady state, the wire harness will be protected by
OCLO2 current level by default. Three other DC over-current
10XS3412
Analog Integrated Circuit Device Data
Freescale Semiconductor
30
FREESCALE [ Freescale ]
