MFS2301BMBACEP datasheet(95/230 Pages) NXP

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NXP Semiconductors

FS23

Safety system basis chip (SBC) with power management, CAN FD and LIN transceivers

19.6.3 FS0B release

When the fail-safe output FS0B is asserted low by the device because of a fault, or after a power up, some

conditions must be validated before allowing the FS0B pin to be released by the device. These conditions are:

• No fault affecting FS0B reported

• Fault error counter = 0

• Device in Normal mode

• Device not in Debug mode and not in INIT mode

• FS_FS0B_LIMP0_REL register filled with the correct value, depending on current WD_TOKEN[15:0] value as

Table 57:

FS_FS0B_

LIMP0_REL[15:0]

B15

B14

B13

B12 B11

B10

Release FS0B

NOT(WD_TOKEN[

0:12])

Release LIMP0

NOT(WD_TOKEN[

3:15])

Release both

FS0B and LIMP0

NOT(WD_TOKEN[

0:6])

NOT(WD_TOKEN[

10:15])

Table 57. FS0B and/or LIMP0 release commands

19.6.4 LIMP0

LIMP0 is an open-drain output that can be used to transition the system in safe state. It is released high by

default. It is asserted low in case of fault and depending on the fault impact configuration. In Low-Power modes

(LPON and LPOFF), LIMP0 works like in Normal mode.

LIMP0 requires an external pullup resistor to VSUP or VDDIO, a 10 nF filtering capacitor to GND for immunity

when LIMP0 is a local pin, and an additional RC network, when LIMP0 is a global pin, to be robust against ESD

GUN and ISO 7637 transient pulses. A weak internal pulldown RPD ensures LIMP0 low level in case of pin lift.

An internal pulldown RPD_STUP ensures LIMP0 is released at startup.

LIMP0 assertion depends on the device configuration during INIT phase. LIMP0 can also be asserted at MCU

request by SPI/I2C, to check the correct HW connection.

aaa-051425

VBOS

LOGIC

LIMP0

To fail-safe

circuitry

VSUP

10 nF

22 nF

10 kΩ

5.1 kΩ

RPD

RPD_STUP

Figure 53. LIMP0 pin implementation

TA = −40 °C to 125 °C, unless otherwise specified. VSUP = 5.5 V to 40 V, unless otherwise specified. All voltages

referenced to ground.

Symbol

Parameter

Min

Typ

Max

Unit

Static electrical characteristics

Table 58. LIMP0 electrical characteristics

FS23

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 7.0 — 16 October 2024

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