E-L9823 Datasheet, PDF (14/19 Pages) STMicroelectronics – Octal low-side driver for bulb, resistive and inductive loads with serial input control, output protection and diagnostic

Functional description
L9823
3.3
Diagnostics
The output voltage at all outputs is compared with the diagnostic threshold, typ 0,55 • V_DD =
V_DG.
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)
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
#3"
3#,+
3)
3/
-3"       ,3"
-3"       ,3"
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14/19
Doc ID 7791 Rev 5