4 Functional Description

L9826

12/17

CD00002120

4.4

Diagnostics

Outputs 1 and 2 features dedicated fault latches. The output status signal is filtered and

latched. The fault latches are cleared during NCS low. The latch stores the status bit, so the

first reading after the error occurred might be wrong. The second reading is right.

Table 6.

Diagnostic Table for outputs 1 and 2 in parallel controlled mode:

Fault condition 1) "output short circuit to Vbat" : 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 low.

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.

For outputs 3 to 8 the output status signals, are fed directly to the SPI register.

Table 7.

The fault condition 1) "output short circuit to Vbat" : 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.

Fault condition 2) "open load" or "output short circuit to GND" is the same as of outputs 1 and

2. At the falling edge of NCS the output status data are transferred to the shift register.

When NSC is low, data bits contained in the shift register are transferred to SDO output et

every rising CLK edge.

Output 1, 2

Output-voltage

Status-bit

Output-mode

off

> DG-threshold

high

correct operation

off

< DG-threshold

low

fault condition 2)

on

< DG-threshold

high

correct operation

on

> DG-threshold

low

fault condition 1)

Output 1 ... 8

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)