The ERRN-pin is a double function pin used for fault communication and device deactivation. When several devices share the same ERRN network (with a shared RERRN) and a fault occurs, then only the device at fault is in fault condition. IERRN(fault) [P_7.5.2] pulls to GND. The ERRN-pin of the other devices is pulled low and as VERRN < VERRN(th) the D-pin starts to rise. When VD > VD(th) the OUT channels of the devices are switched-off
The block diagram shows two LITIX™ Basic+ ICs sharing the same ERRN network:
The fault detection and communication of two ICs sharing the same ERRN network is described below:
IC at fault:
(1): an OL or SC occurs in one of the OUT channels
(2): VOUT comparison: is there a fault or not
(3): if at fault, then IERRN(fault) pulls ERRN-pin to GND
(4): If VERRN < VERRN(th) then the fault is detected
(5): When fault is detected for at least tfault (~80usec) then a pull-up current ID(fault) is sourced from D-pin and its voltage starts to rise
(6): When VD(th) is reached, all channels are switched off
IC on the same ERRN network w/o fault
(1): Voltage at ERRN-pin is VERRN < VERRN(th)
(2): voltage at D-pin rises
(3): When VD > VD(th) the OUT channels are switched off
For more information on LITIX™ Basic+ diagnostic features check the "LITIX™ Basic+ LED driver family: Diagnosis and fault management" application note