ETAS
Hardware Description
XETK-S22.0 - User’s Guide
22
4.6
ECU Voltage Supervisor
The ECU voltage (VDD) is monitored by the XETK to recognize whether the ECU
is switched on or off. Additionally the ECU RAM standby voltage (VDDSTBY) is
monitored to determine if the standby RAM content is still valid. These two sig-
nals are only used for monitoring therefore the load current is negligible.
The XETK-S22.0 provides two opportunities to supply and supervise the ECU
RAM standby voltage:
• The XETK-S22.0 monitors the VDDSTBY supply on board the XETK. The
microcontroller’s standby power supply pin must be connected to the
XETK pin VDDSTBY.
• The XETK-S22.0 monitors the VSTBY pin, provided by the ECU connec-
tion. The microcontroller’s standby power supply pin must be connected
to the XETK pin VSTBY. The microntroller’s standby power supply may
be provided by the ECU or by the XETK.
NOTE
The XETK-S22.0 only allows switching between reference page and working
page if there is a valid voltage at the sense pin and the working page has been
initialized by the calibration and development system.