ETAS
Hardware Description
FETK-S2.1 - User’s Guide
22
4.4
Power Supply
The FETK-S2.1 requires a permanent power supply. It is typically powered
directly from the car battery. The input voltage may vary (see chapter 7.5
on page 36). In case of higher input voltages to the FETK, additional voltage
protection is required.
The FETK-S2.1 will also accept voltage dips down to 3 V (for additional details
of low voltage operation, see ISO standard 16750).
From the input battery voltage, switch-mode power supplies provide all neces-
sary voltages on the FETK-S2.1. The power supply of the ECU is not affected by
the FETK-S2.1. An automatic switch ensures that the power supply of the
FETK-S2.1 is automatically switched on and off when the FETK enters and
leaves its standby (sleep) mode.
The FETK-S2.1 is supplied with power through the connector CON2.
Fig. 4-5
Location of the FETK-S2.1 Power Supply Connectors
4.5
ECU Voltage Supervisor
The ECU voltage (VDDP) is monitored by the FETK to recognize whether the
ECU is switched on or off. Additionally the ECU RAM standby voltage (VDDS-
BRAM) is monitored to determine if the standby RAM content is still valid.
These two signals are only used for monitoring therefore the load current is
negligible.
The FETK-S2.1 monitors the VDDSBRAM supply on board the FETK. The micro-
controller’s standby power supply pin must be connected to the FETK pin
VDDSBRAM.
NOTE
The FETK-S2.1 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.
CON2
