FS6500 datasheet(64/153 Pages) NXP

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NXP Semiconductors

FS6500-FS4500-ASILD

Safety power system basis chip with CAN FD and LIN transceivers

12.7.4.1 Current limitation

A current limitation is implemented to avoid uncontrolled power dissipation of the internal MOSFET or external

PNP transistor. By default, the current limitation threshold is selected based on the auto detection of the

external PNP during start-up phase.

• When the internal MOSFET transistor is used, the current is limited to ICCA_LIM_INT and the regulator is kept on

• When the external PNP transistor is used, the current is limited to ICCA_LIM_OUT and the regulator is switch

off after a dedicated duration tCCA_LIM_OFF under current limitation. A SPI command is needed to restart the

regulator.

In case of an external PNP configuration only, the lowest current limitation threshold can be selected by the SPI

in the register INIT_VREG instead of the highest one. A current limitation foldback scheme is implemented to

reduce the current limitation to ICCA_LIM_FB when VCCA is below VCCA_LIM_FB, limiting the power dissipation in

the external PNP transistor during a short-circuit to GND of the VCCA pin.

12.7.4.2 Voltage monitoring

The overvoltage detection switches off the regulator. The regulator remains on if an undervoltage is detected. A

diagnostic is reported in the dedicated register, generating an Interrupt and may bring the application into fail-

safe state, depending on the supervisor configuration (register INIT_VCCA_OVUV_IMPACT).

12.7.5 VAUX voltage regulator

VAUX is a highly flexible linear voltage regulator, which can be used either as an auxiliary supply dedicated to

additional device in the ECU or as a sensor supply (i.e. outside the ECU). An external PNP transistor must be

used (no internal current capability).

If VAUX is not used in the application, the VAUX, VAUX_E, and VAUX_B pins must be left open. It is

recommended to turn the VAUX driver off and disable the VAUX safety impact by the SPI (VAUX_EN=0 in

REG_MODE register and all bits of INIT_VAUX_OVUV_IMPACT register at 0).

If VAUX is used as an auxiliary supply, the output voltage is selectable between 5.0 V and 3.3 V. Since this

voltage rail can be used to supply MCU IOs, the selection is done with an external resistor connected between

the SELECT pin and ground or VPRE. In such case, the voltage accuracy is ±3.0 %, with a maximum output

current capability of 400 mA.

If VAUX is used as a sensor supply rail, the output voltage is selectable between 5.0 V and 3.3 V. VCCA can

be used as reference for the sensor supply used as tracker. In this case, the VAUX voltage must match VCCA,

limiting the resistor configuration at the SELECT pin to 5.1 kΩ (VAUX = VCCA = 3.3 V) and 12 kΩ (VAUX = VCCA

= 5.0 V). The tracker mode selection is done during the INIT phase and secured (bit VAUX_TRK_EN in the

INIT_VREG register). The tracking accuracy is ±15 mV.

FS6500-FS4500-ASILD

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Product data sheet

Rev. 8 — 5 August 2024

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FS6500 Datasheet(PDF) 64 Page - NXP Semiconductors