Datasheet

NXP Semiconductors 33
10XS3435
7.3 Protection and diagnostic features
7.3.1 Protections
7.3.1.1 Overtemperature fault
The 10XS3435 incorporates overtemperature 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] till 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.
7.3.1.2 Overcurrent fault
The 10XS3435 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 17, page 41).
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 overcurrent protection will be fitted to inrush current, as shown in
Figure 5. This overcurrent protection
is programmable: OC[1:0] bits select overcurrent slope speed and OCHI1 current step can be removed in case of OCHI bit is set to [1].
Figure 14. Overcurrent detection profile
In steady state, the wire harness will be protected by OCLO2 current level by default. Three other DC overcurrent 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 overcurrent 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 internal PWM module, the 10XS3435 incorporates also a cooling bulb filament management if OC_mode and
Xenon are set to logic [1]. In this case, the 1
st
step of multi-step overcurrent 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.
hson signal
Over-current thresholds
PWM
fault_control
hson