MFS2401AVMAFES datasheet(31/151 Pages) NXP

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NXP Semiconductors

FS2400

Fail-safe system basis chip with SMPS and LDO, CAN FD transceiver

14 Power management

Regulator

Type

Input supply

Output range

Max DC current

HV buck regulator

V1_IN

(V1+ 1 V to 40 V)

1.9 V to 5.5 V

400 mA

HV Linear regulator

V3_IN

(V3+500 mV to 40 V)

3.3 V or 5 V

150 mA

Table 12. FS24 regulators list

The FS24 includes two regulators, all supplied in parallel from the battery line.

The FS24 starts when VSUP > VSUP_UVH, with VBOS first, followed by V1 (HVBUCK), and the power-up

sequencing from the OTP programming for the remaining regulator V3 (HVLDO).

14.1 V1 HVBUCK: High-voltage buck regulator

14.1.1 Functional description

HVBUCK block is a high-voltage, integrated synchronous buck. It can be used to supply the ECU MCU and

other local loads inside the ECU.

General operation

HVBUCK operates in force PWM or PFM modes and uses internal N-type FETs. The output voltage (1.9 V to 5

V) and the switching frequency (450 kHz or 2.25 MHz) are configurable by OTP. Compensation is ensured by

internal circuitry.

The current in the inductor is sensed via the internal FETs, through the High-Side switch when it’s turned on

and through the Low-Side switch when it’s turned on. This information is used to compute an average that is

reflecting the output DC current.

Mode-specific operation

HVBUCK operates in PWM when the FS24 is in Normal mode and in PFM when the FS24 is in Low-power

on mode (LPON). HVBUCK output voltage can be different in Normal mode and in LPON mode. The voltage

rampup/down between the normal and the LPON voltages is done in PWM mode.

Current limitation

HVBUCK has current limitation protection features. In PWM mode, HVBUCK has both peak and average

current limitations, configurable by OTP. In PFM mode, HVBUCK has a peak current limitation, also configurable

by OTP. An overcurrent detection is also implemented on the Low-Side MOSFET, to detect high-negative

current in case of output short to the battery.

When HVBUCK current reaches one of its current limitations, V1OC_I flag is set. The regulator stays enabled

but it induces a duty-cycle reduction and therefore an output voltage drop, which could lead to an undervoltage

detection (V1UV_I flag generated).

Input voltage range

When IBUCK current load is higher than 400 mA, V1_IN shall be above (VBUCK + ((Max(RLS_BUCK) +

Max(RDCR_LBUCK)) x IBUCK))/0.905 to guarantee HVBUCK output-voltage regulation (4.06 V at IBUCK = 400 mA

with RDCR_LBUCK = 200 mΩ and VBUCK = 3.3 V).

Thermal shutdown

When a thermal shutdown is detected, the regulator is disabled and V1TSD_I flag is generated.

FS2400

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

Product data sheet

Rev. 4 — 23 October 2024

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