L99LDLH32 datasheet(31/142 Pages) STMICROELECTRONICS

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DS12879 Rev 6

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L99LDLH32

Functional description

141

After tDIAG_BLANK_x elapses, a failure counter starts and any channel fault is validated after

N_Fails number of detected failures (also non-consecutive). The N_Fails readings are kept

in memory up to N_Fails_reset (number of consecutive NOT failures detection), then the

counter will be reset.

Diagnostic validation strategy is applied for any possible load fault: O/LED short to ground,

open string, short to VPRE_REG. If the on-time of any channel is shorter than the configured

blanking time, the device automatically disables fault detection on that channel and sets the

pre-regulator voltage feedback to maximum.

5.3.2

Fault bus capability

In the L99LDLH32, there is 1 fault pin with "Fault Bus" capability: 1 open drain fault pin

(FAULT) is associated with 1 Direct Input (DIN), output channels are mapped according to

DIN_MAP_CHx.

The fault pin is bidirectional, active low. Several fault pins of several devices can be

connected together to have a common fault bus associated to a particular light function.

This allows an automatic deactivation of complete light function in case of fault on single

O/LED string only, according to the selected Fault reaction mode.

There is, in fact, 1-bit (FAULT_REACT_MODEx - see FTP/RAM memory map, Chapter 7)

for fault reaction mode configuration:

5.3.3

Thermal warning

The L99LDLH32 integrates a temperature warning with one threshold.

If the junction temperature (TJ) of the device – read by internal ADC - rises above the

warning temperature threshold (TTW), the thermal warning status bit (TW – see RAM

memory map, Chapter 7) is set.

Thermal warning is also reported in the Global Status Byte register, in particular Global

Warning (GW) bit is set.

Table 7. Diagnostic blanking time

DIAG_BLANK_x [1÷0]

tDIAG_BLANK_x [us]

100

150

200

Table 8. Fault reaction mode

FAULT_REACT_MODE <0>

Fault Reaction Mode

Fault on one string => all strings of same fault bus deactivated

Fault on one string => no action on other strings

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