The device compares each channel V_DS with V_{DS_OL} and sets the corresponding OSMx bits accordingly. The bits are updated every time OSM register is read.

• V_DS < V_{DS_OL} → OSMx = 1b

A diagnosis current I_OL in parallel to the power switch can be enabled by programming the IOLx bit, which can be used for Open Load at OFF detection. Each channel has its dedicated diagnosis current source. If the diagnosis current I_OL is enabled or if the channel changes state (ON → OFF or OFF → ON) it is necessary to wait a time t_OSM for a reliable diagnosis. Enabling I_OL current sources increases the current consumption of the device. Even if an Open Load is detected, the channel is not latched OFF.

See Figure 7-13 for a timing overview (the values of IOLx refer to a channel in normal operation properly connected to the load).

Figure 7-13 Output Status Monitor timing

Output Status Monitor diagnostic is available when V_M = V_{M_NOR} and V_DD ≥ V_{DD_UVLO}.

Due to the fact that Output Status Monitor checks the voltage level at the outputs in real time, for Open Load in OFF diagnostic it is necessary to synchronize the reading of OSM register with the OFF state of the channels.

Figure 7-14 shows how Output Status Monitor is implemented at concept level.

Figure 7-14 Output Status Monitor

In Standard Diagnosis the bit OLOFF represents the OR combination of all OSMx bits for all channels in OFF state which have the corresponding current source I_OL activated.

When the DISOL bit is 1b, open load detection is disabled by disabling all the I_OL current sources.