Datasheet

Functional description L9823
14/19 DocID7791 Rev 7
3.3 Diagnostics
The output voltage at all outputs is compared with the diagnostic threshold, typ 0,55  V
DD
=
V
DG
.
Fault condition 1
Output short circuit to Vbat:
 For SFPD = Low the output was switched on and the voltage at the output exceeded
the diagnostics threshold due to overcurrent, the output overload latch was set and the
output has been switched off. The diagnostic bit is high.
 For SFPD = high the output was switched on and the voltage at the output exceeds the
diagnostics threshold. The output operates in current regulation mode or has been
switched off due to thermal shutdown. The status bit is high.
Fault condition 2
Open load or output short circuit to GND:
 The output is switched off and the voltage at the output drops below the diagnostics
threshold, because the load current is lower than the output diagnostic current source,
the load is interrupted. The diagnostic bit is low.
 At the falling edge of CSB the output status data are transferred to the shift register.
When SCB is low, data bits contained in the shift register are transferred to SO output
at every rising SCLK edge.
Figure 5. Pulse diagram to read the outputs status register
Table 7. Diagnostic for outputs
Output Output voltage Status bit Output mode
off > DG-threshold high correct operation
off < DG-threshold low fault condition 2)
on < DG-threshold low correct operation
on > DG-threshold high fault condition 1)
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