FS23 datasheet(26/230 Pages) NXP

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NXP Semiconductors

FS23

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

12.6 Power sequencing

V1 is the first regulator to start automatically in Slot 0, then the other regulators start following the OTP

power sequencing configuration. Three slots are available, from SLOT_0 to SLOT_2, to program the start-up

sequence of V2 and V3 regulators, as well as I/Os release or assertion.

The power-up sequence starts at SLOT_0 towards SLOT_2. The power-down sequence is executed in reverse

order, starting at SLOT_2 toward SLOT_0.

All regulators not assigned in any slot are not started during the power-up sequence. These regulators can be

started (or not) later when the main state machine is in NORMAL mode with an SPI/I2C command to write in

M_REG_CTRL register if they were enabled by OTP.

Slot 0 duration depends on the device version. In the HVBUCK version (FS232x), Slot 0 lasts at least 500 µs

and until the soft start of the DC-DC is done, which depends on the OTP configuration. In the HVLDO1 version

(FS230x), it lasts 500 µs (fixed duration).

Slot 1 and Slot 2 always last 500 µs.

When waking up from LPON, it is possible to reduce the start-up time by bypassing Slot 1 and Slot 2. In this

case, the V2 and V3 regulators must be configured to start in Slot 0, or later by SPI/I2C, as their correct soft

start will not be guaranteed otherwise. Bypassing Slot 1 and Slot 2 is enabled by SPI/I2C with SLOT_BYP bit. It

can also be preconfigured by OTP using SLOT_BYP_OTP bit.

aaa-051439

Power up

Power down

From

WAIT VSUP

NORMAL

SLOT_0

VSUP > VSUP_UV

TSOFT_START_V1 and (TSLOT_UP

or (SLOT_BYP = 1 and

Go2LPON_latch = 1))

TSLOT_UP

SLOT_BYP = 1 and

Go2LPON_latch = 1

SLOT_1

SLOT_2

From

NORMAL

LPON

LPOFF

SLOT_2

Go2LPON = 1 or Go2LPOFF = 1

TSLOT_DOWN

10 µs

TRAMP_DOWN_V1 + 10 µs

SLOT_1

SLOT_0

Figure 13. Power sequencing

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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