33480 datasheet(23/39 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33480

PROTECTION AND DIAGNOSIS FEATURES

Output Protection Features

The 33480 provides the following protection features:

• Protection against transients on VBAT supply line (per

ISO 7637)

• Active clamp, including protection against negative

transients on output line

• Overtemperature

• Severe and resistive Overcurrent

• Open Load during ON state

These protections are provided for each output (OUT1:5).

Overtemperature detection

The 33480 provides overtemperature shutdown for each

output (OUT1:OUT5). It can occur when the output terminal

is in the ON or OFF state. An overtemperature fault condition

results in turning OFF the corresponding output. The fault is

latched and reported via SPI. To delatch the fault and be able

to turn ON again the outputs, the failure condition must be

removed (T< 175°C typically) and:

• if the device was in Normal Mode, the output

corresponding register (bit D7) must be rewritten.

Application of complete OCHI window (OCHI1+OCHI2

during t2) depends on toggling or not toggling D7 bit.

• if the device was in Fail Mode, the corresponding output

is locked until restart of the device: wake up from Sleep

Mode or VBATPOR.

The SPI fault report (OTS bit) is removed after a read

operation.

Overcurrent detections

The 33480 provides intelligent overcurrent shutdown (see

Figure 10) in order to protect the internal power transistors

and the harness in the event of overload (fuse characteristic).

Figure 10. Double overcurrent window in Normal Mode

OCHI (IOCHI1 and then IOCHI2) is only activated after

toggling D7 bit in Normal Mode. In Fail Mode, the control of

OCHI window is provided by the toggles: IGN_ON,

Flasher_ON. The current thresholds (IOCHI1 , IOCHI2 and

IOCLO) and the time (t1 and t2) are fixed numbers for each

driver. After t2, OCLO current threshold is set to protect in

steady state.

OUT2 is default loaded with the Xenon profile. The use of

H7 bulbs at this output requires SPI programming (Xenon

bit).

In case of overload (OCHI1 or OCHI2 or OCLO detection),

the corresponding output is disabled immediately. The fault is

latched and the status is reported via SPI. To delatch the

fault, the failure condition must be removed and:

For OCHI1:

• if the device was in Normal Mode: the output

corresponding register (bit D7) must be rewritten D7=1.

Application of complete OCHI window depends on

toggling or not toggling D7 bit.

• if the device was in Fail Mode, the failure is locked until

restart of the device: wake up from Sleep Mode or

VBATPOR.

For OCHI2 and OCLO:

• if the device was in Normal Mode: the output

corresponding register (bit D7) must be rewritten D7=1.

Application of complete OCHI window depends on

toggling or not toggling D7 bit.

• if the device was in Fail Mode, Autorestart is activated.

The device Autorestart feature provides a fixed duty

cycle and fixed period with OCHI1 window.

Autorestart feature resets OCHI2 or OCLO fault after

corresponding Autorestart period.

The SPI fault reports are removed after a read operation:

- OC bit=(OCHI1) or (OCHI2) fault

- OVL bit=(OCHI1) or (OCHI2) or (OCLO) fault

Overvoltage detection and active clamp

The 33480 provides an active gate clamp circuit in order to

limit the maximum drain to source voltage.

In case of overload on an output the corresponding switch

(OUT[1 to 5]) is turned off which leads to high voltage at Vbat

with an inductive Vbat line. When Vbat voltage exceeds

VBAT_CLAMP threshold, the fast turn-off on the

corresponding output is deactivated and the drain to source

voltage is limited by the active clamp circuit (VCLAMP_DS).

OCHI1

OCHI2

OCLO

Output current

time

33480 Datasheet(PDF) 23 Page - Freescale Semiconductor, Inc

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