AS8221
Data Sheet - Detailed Description
8.10.2 ERRN Signalling
The ERRN signalling is shown in Table 8.
Table 8. ERRN signalling
HOST COMMAND
SUPPLY VOLTAGE FLAG EVENT
RWAKE FLAG LWAKE FLAG
ERRN
VIO
STBN
EN
L
X
H
X
X
H
H
H
Not failure
If rising edge at EN, then
NOT [error flag] else L
L
L
L
If rising edge at EN, then
NOT [error flag] else H
L
L
X
H
L
L
L
L
L
H
L
L
L
L→H
L
L
L
L
L
L
X
X
X
X
X
X
X
H
H→L
H→L
L
L→H
H
L→H
H
L→H
X
L
X
L
8.11 Loss of ground
Whenever a loss of ground is detected, the bus lines are switched Idle_HZ with the precondition that the host pins are open. Either error or no
error can be indicated on the ERRN pin.
8.12 Error Flags Description
8.12.1 Undervoltage
ꢀ
ꢀ
ꢀ
UVVBAT_DET: The VBAT undervoltage flag is set if the VBAT voltage falls below VBATTHL for longer than tUV_DETECT and is reset if the
VBAT voltage reaches a voltage level higher than VBATTHH for longer than tUV_DETECT
.
UVVIO_DET: The VIO undervoltage flag is set if the VCC voltage falls below VCCTHL for longer than tUV_DETECT and is reset if the VCC
voltage reaches a voltage level for longer than VCCTHH after tUV_DETECT
.
UVVCC_DET: The VCC undervoltage flag is set if the VIO voltage falls below VIOTHL for longer than tUV_DETECT and is reset if the VIO volt-
age reaches a voltage level higher than VIOTHH for longer than tUV_DETECT
.
8.12.2 Bus Error (BUSERR)
The bus error flag is set if 2 consecutive rising edges on the TxD pin without any rising edge on the RxD pin are detected or if 2 consecutive
falling edges on the TxD pin without any falling edge on the RxD pin are detected. This flag is reset if a rising edge on the TxD pin is followed by
a rising edge on RxD pin before the next TxD rising edge or if a falling edge on the TxD pin is followed by a falling edge on RxD pin before the
next TxD falling edge. This flag can be set or reset only in NORMAL mode when the transmitter is enabled. The flag is reset at POWER-OFF.
8.12.3 BP Open Line (BP_OL)
The BP_OL can only be set/reset in NORMAL mode if the driver is enabled. The flag is set if the absolute current at BP is lower than ITHL during
transmission of Data0 and Data1 for a time longer than tBUS_ERROR. The flag is reset in POWER-OFF mode and if the absolute current at BP is
higher than ITHL during transmission of Data0 and Data1 for a time longer than tBUS_ERROR
.
8.12.4 BM Open Line (BM_OL)
The BM_OL can only be set/reset in NORMAL mode if the driver is enabled. The flag is set if the absolute current at BM is lower than ITHL during
transmission of Data0 and Data1 for a time longer than tBUS_ERROR. The flag is reset in POWER-OFF mode and if the absolute current at BM is
higher than ITHL during transmission of Data0 and Data1 for a time longer than tBUS_ERROR
.
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