35FS6500 datasheet(56/139 Pages) NXP

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NXP Semiconductors

35FS4500-35FS6500-ASILB

Grade 0 safety power system basis chip with CAN FD transceiver

aaa-037774

FB_CORE

VCORE voltage

PGND

GND

R3b

R4b

GND

FCRBM

activate RSTB

and/or FSxB

Figure 40. Feedback core resistor bridge monitoring (FCRBM)

If the second resistor bridge (R3b/R4b) is not mounted, FCRBM must be connected directly to FB_CORE to

satisfy FB_CORE = FCRBM in all conditions.

12.7.2.5 VCORE efficiency

VCORE efficiency versus current load is given for information based on typical external component criteria

described in Figure 41, close to the graph and at three typical VCORE voltages (5.0 V, 3.3 V, and 1.2 V),

covering most of the MCU supply ranges. The efficiency is valid above a 200 mA load on VCORE to be in

continuous mode in the 2.2 µH inductor. The efficiency is calculated and has to be verified by measurement

at the application level. One major contributor degrading the efficiency at VCORE = 1.2 V is the external diode

during the recirculation phase. The lower the diode forward voltage (VF) is, the better the efficiency.

aaa-037775

EXT. Devices

Converter

RDS(on)

VCORE

tSW_ON

tSW_OFF

Overdrive

VDIODE

300 pF

12 ns

10.0 V

2.2 µH

20 µF

5.0 mΩ

20 mΩ

200 mΩ

0.35 V

ESR

COUT_VCORE

L coil

Freq

DCR coil

MOSFET switch

2400 kHz

1.2 V, 3.3 V, 5.0 V

VCORE Efficency vs. ICORE

ICORE current (A)

2.4

1.6

0.8

2.0

1.2

0.4

VCORE

efficiency

(%)

VCORE = 1.2 V

VCORE = 5.0 V

VCORE = 3.3 V

Figure 41. VCORE efficiency

12.7.2.6 VCORE linear regulator

The 35FS4500 voltage regulator is a linear regulator. The pass device, connected to VPRE, is integrated. The

output voltage range is configurable from 1.0 V to 5.0 V, and adjustable around these voltages with an external

resistor divider (R3/R4) connected between VCORE and the feedback pin (FB_CORE) (see Figure 42). VCORE =

VCORE_FB x ((R3 + R4)/R4).

The voltage accuracy is ±2.0 % (without the external resistor bridge R3/R4 accuracy) and the max. output

current is 0.5 A. In this case, the BOOT_CORE and COMP_CORE pins (used in buck converter mode only)

35FS4500-35FS6500-ASILB

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

Product data sheet

Rev. 3 — 5 August 2024

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