Safety Manual for MPC5777M, Rev. 1.1
Functions of external devices for ASIL D applications
NXP Semiconductors60
NOTE
Voltage monitors are provided on the MPC5777M to monitor the internal
supplies of the device. See table “POR and voltage monitors description” in
the “Power management” chapter of the MPC5777M Reference Manual for
a list of monitored supplies.
LVD/HVD are necessary to ensure logic functionality. External LVD can be
removed if the failure can be detected by other means, but the external HVD
is necessary to prevent physical damage.
Assumption: [SCG18.091] External supervision shall hold the MPC5777M in a Safe state
MCU
and the
system in its Safe state
system
if the external voltage is outside specifications. The MCU shall be protected
against voltages over the maximum survivable level of the technology. [end]
Recommendation: It is recommended to protect the MCU against voltage above the maximum survivable
level of the technology (for example, using a Zener diode) to prevent destruction of the MCU.
NOTE
See the MPC5777M Data Sheet’s “Absolute maximum ratings” and “DC
electrical specifications” sections for power supplies requirements.
[SCG18.123]The MPC5777M embeds two types of voltage supervisors, Low Voltage Detect (LVD) and
High Voltage Detect (HVD) monitors. Safety relevant voltages are supervised for voltages that are out of
these ranges. Since safety relevant voltages have the potential to disable the failure indication mechanisms
of the MPC5777M (such as FCCU, Pads, and so on) their error indication directly causes a transition into
the Safe state
MCU
(for example, reset assertion). [end]
Some LVDs and HVDs are configurable and enabled by default. Application should not disable safety
relevant LVDs or HVDs. See the “POR and voltage monitors description” table in the “Power
management” chapter of the MPC5777M Reference Manual for the list of configurable LVDs and HVDs.
4.5 Error Out Monitor (ERRM)
The FCCU has two external pins: FI[0] and FI[1]. An external device must be connected to the FCCU via
FI[0] and optionally FI[1] to continually monitor the error output pins of the FCCU.
Assumption: [SCG18.092]The overall system needs to include measures to monitor the error output
pin(s) of the MPC5777M and move the system into a Safe state
system
when an error is indicated. [end]
Table 2. MPC5777M required external monitors
Name Description External Monitor Required
VDD_HV_ADR_D Voltage reference of ADC sigma/delta module LVD/HVD
VDD_HV_ADR_S Voltage reference of ADC SAR module LVD/HVD
VDD_HV_IO_MAIN High voltage Power supply for the I/O’s HVD
VDD_HV_IO_FLEX FlexRay/Ethernet 3.3 V I/O supply HVD
VDD_HV_IO_JTAG Oscillator and JTAG pin supply HVD
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