AS3636 datasheet(19/42 Pages) AMSCO

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AS3636

Preliminary Datasheet, Confidential - D e ta i l e d D e s c r i p t i o n

Protection and Fault Detection Functions

The protection functions protect the AS3636 and the external devices against physical damage. In case of a failure a

13 by a readout of the Interrupt Status Register (see page 35). If enabled by

the Interrupt Mask Register (see page 35), any fault condition will raise an interrupt by pulling INT low. The interrupt

output INT return to open drain, once the fault condition is cleared.

Indicator LED fault (ILF)

If the indicator LED is enabled, an indicator LED fault is triggered under the following conditions:

1. In case of no or a broken LED and the current through pin IND is below IIND_OUTOPEN.

2. If the LED is shorted and the voltage on IND does not reach VINDSHORT.

If one of these conditions is detected the bit ILF is set but the current source is not disabled

14.

Charge transformer fault (CTF)

If the Xenon charger is started and the AS3636 detects a too low inductance

15 of the transformer, the Xenon is

stopped and the bit CTF is set.

Boost converter fault (BCF)

To limit the maximum current from the battery, the DCDC converter limits its current through the coil to ILIMIT. If within

a single cycle ILIMIT is reached and afterwards (still in the same cycle) the current through the coil reaches zero, a

shorted coil is assumed. If this condition is detected, the DCDC is stopped, the current source is disabled (if enabled)

and the bit BCF is set.

Xenon charger and strobe timeout fault (TOF)

During every charging of the Xenon capacitor, the register charge_time monitor the charge time. If the register reaches

FFh, the Xenon charger is stopped and the bit TOF is set.

The register TOF is also set, if the strobe length (from pin STROBE) exceeds 2ms

16. In this case, the IGBT_GATE is

switched off automatically.

Overtemperature fault (OTPF)

If the AS3636 junction temperature exceeds TOVTEMP the register bit OTPF is set. The bit OTPF is automatically reset,

once the junction temperature drops below TOVTEMP-TOVTEMPHYST.

Autofocus LED fault (AFF)

If the autofocus LED (pin VLED) is enabled, an autofocus LED fault is triggered under the following conditions:

1. If the LED is shorted and the voltage on VLED does not reach VVLEDSHORT.

2. If the voltage on VLED stays below VVLEDOPEN.

If one of these conditions is detected, the DCDC converter is stopped, the current source is disabled and the bit AFF is

set.

Xenon strobe self test fault (SSTF)

The xenon strobe is only used upon self testing - for details see section Self Testing on page 17. The fault bit is set if

the re-charge time for the Xenon charger is above 0.4s or below 0.1s.

Supply undervoltage Protection

If the voltage on the pin VBATINT (=battery voltage) is or falls below VUVLO, the AS3636 is kept in shutdown state and

all registers are set to their default state.

13.Except overtemperature protection fault OTPF.

14.To avoid erroneously disabling of the indicator current source due to short voltage drops on the supply.

15.An inductance below 0.5µH will be detected as a fault. Above 3.5µH, a valid transformer is detected.

16.The exact duration can vary between 930µs to 2.15ms.

AS3636 Datasheet(PDF) 19 Page - ams AG

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