Data Sheet
23
Rev. 1.00
2017-07-31
TLE9262BQXV33
System Features
5.1.1
Device Configuration and SBC Init Mode
The SBC starts up in SBC Init Mode after crossing the power-on reset
V
POR,r
threshold (see also
Chapter 15.3
)
and the watchdog will start with a long open window (
t
LW
).
During this power-on phase following configurations are stored in the device:
•
The device behavior regarding a watchdog trigger failure and a VCC1 overvoltage condition is determined by
the external circuitry on the INT pin (see below)
•
The selection of the normal device operation or the SBC Development Mode (watchdog disabled for debugging
purposes) will be set depending on the voltage level of the FO3/TEST pin (see also
Chapter 5.1.7
).
5.1.1.1
Device Configuration
The configuration selection is intended to select the SBC behavior regarding a watchdog trigger failure.
Depending on the requirements of the application, the VCC1 output shall be switched OFF and the device shall
go to SBC Fail-Safe Mode in case of a watchdog failure (1 or 2 fails). To set this configuration (Config 2/4), the
INT pin does not need an external pull-up resistor. In case VCC1 should not be switched OFF (Config 1/3), the
INT pin needs to have an external pull-up resistor connected to VCC1 (see application diagram in
Chapter 17.1
).
Figure 5
shows the timing diagram of the hardware configuration selection. The hardware configuration is
defined during SBC Init Mode. The INT pin is internally pulled LOW with a weak pull-down resistor during the
reset delay time
t
RD1
, i.e.after VCC1 crosses the reset threshold VRT1 and before the RO pin goes HIGH. The INT
pin is monitored during this time (with a continuos filter time of
t
CFG_F
) and the configuration (depending on
the voltage level at INT) is stored at the rising edge of RO.
Note:
If the
POR
bit is not cleared then the internal pull-down resistor will be reactivated every time RO is
pulled LOW the configuration will be updated at the rising edge of RO. Therefore it is recommended
to clear the
POR
bit right after initialization. In case there is no stable signal at INT, then the default
value ‘0’ will taken as the config select value = SBC Fail-Safe Mode.
