L9300 datasheet(58/178 Pages) STMICROELECTRONICS

58 / 178 page

Figure 35. Driver behavior in short to battery condition: HS_config=1, SW_cntr=1, OVC_R=1

GADG1807171607PS

Solenoid supply disconnection

When solenoid driver is configured in LS configuration recirculation happens through the internal HS FET. If the

supply of HS power stage is lost, due to the inductive nature of the load, voltage at LOADx pin could rise above

absolute ratings damaging the device; to prevent such a condition a clamping structure is integrated in the LS

driver. If the clamping structure is activated in normal operation it means a disconnection of HS supply happened:

as a consequence the solenoid channel is put in tristate and a dedicated diagnostic bit is set. To restart the

channel the microcontroller has to clear the fault bit (reading the fault register) and to enable the channel again.

LS clamp circuitry is automatically disabled when VBATP over voltage is detected to avoid unwanted clamp

activation during load dump event.

OFF State Diagnostic

The device provides off-state diagnostic for each channel; simplified schematic of implemented diagnostic is

shown in Figure 36 and Figure 37 depending on the chosen configuration.

By default diagnostic pull up/down currents are disabled and comparator outputs are masked by internal logic, to

enable OFF state diagnostic the channel must be put first in tristate condition and then (if not already done with

previous SPI frames) diagnostic must be enabled. Once the desired channel is put in tristate a false diagnostic

can be sensed due to the time needed to discharge output voltage through the load. To avoid unwanted fault

detection a blanking time is implemented: during this time diagnostic comparators are masked. The diagnostic

blanking time is programmable through SPI to choose the proper value depending on external load value and

ESD capacitor connected to the output pin. Fault conditions are latched and cleared on SPI read, however they

do not prevent enabling of the solenoid channels.

OFF state diagnostic comparators are the same for both HS and LS configuration and their output is decoded

from internal logic to set SPI fault bits according to the following figure:

L9300

Valve drivers

DS12258 - Rev 5

page 58/178

L9300 Datasheet(PDF) 58 Page - STMicroelectronics