MFS5600AMBAFES datasheet(35/118 Pages) NXP

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NXP Semiconductors

FS5600

Automotive buck regulator and controller with voltage monitors and watchdog timer

14.3 Spread spectrum

The internal oscillator provides a programmable frequency spread spectrum to help manage EMC in automotive

applications. Spread spectrum is enabled by setting the FSS_EN bit. The initial value of FSS_EN is loaded from

OTP_FSS_EN and can be subsequently changed via I2C.

14.4 SW1 and SW2 switching frequency selection

The switching frequencies of SW1 and SW2 are derived from the 20 MHz clock. SW1 and SW2 use clock

pulses that are shifted by one 20 MHz clock period (50 ns) with respect to each other to allow interleaving of the

switching edges.

The 20 MHz clock is divided internally to form CLK1 and CLK2 as shown in the block diagram.

CLK1 uses a divide ratio of 8 if OTP_CLK1_DIV = 0 and a divide ratio of 9 if OTP_CLK1_DIV = 1.

CLK2 uses a divide ratio of 48 if OTP_CLK2_DIV = 0 and a divide ratio of 64 if OTP_CLK2_DIV = 1.

Using the OTP_SW1_CLKSEL and OTP_SW2_CLKSEL, switching frequency SW1 and SW2 regulators can be

assigned to either CLK1 or CLK2. Refer to the table below for the available combinations.

OTP_SW1/2_CLKSEL

selection

Switching frequency

OTP_SW1_CLKSEL = 0;

OTP_SW2_CLKSEL = 0;

Switching frequency

OTP_SW1_CLKSEL = 1;

OTP_SW2_CLKSEL = 1;

CLK1/CLK2 Selection

OTP_CLK1_DIV = 0

OTP_CLK1_

DIV = 1

OTP_CLK2_DIV = 0

OTP_CLK2_DIV = 1

SW1/SW2 Fsw at 16 MHz

clock

2.0000 MHz

1.7778 MHz

0.3333 MHz

0.25 MHz

SW1/SW2 Fsw at 17 MHz

clock

2.1250 MHz

1.8889 MHz

0.3542 MHz

0.265625 MHz

SW1/SW2 Fsw at 18 MHz

clock

2.2500 MHz

2.0000 MHz

0.3570 MHz

0.28125 MHz

SW1/SW2 Fsw at 19 MHz

clock

2.375 MHz

2.1111 MHz

0.3958 MHz

0.296875 MHz

SW1/SW2 Fsw at 20 MHz

clock

2.5000 MHz

2.2222 MHz

0.4167 MHz

0.3125 MHz

SW1/SW2 Fsw at 21 MHz

clock

2.6250 MHz

2.3333 MHz

0.4375 MHz

0.328125 MHz

SW1/SW2 Fsw at 22 MHz

clock

2.7500 MHz

2.4444 MHz

0.4583 MHz

0.34375 MHz

SW1/SW2 Fsw at 23 MHz

clock

2.8750 MHz

2.5556 MHz

0.4792 MHz

0.359375 MHz

SW1/SW2 Fsw at 24 MHz

clock

3.0000 MHz

2.6667 MHz

0.500 MHz

0.375 MHz

Table 29. SW1 and SW2 switching frequency selection

14.5 External clock synchronization

The MODE/SYNCIN pin can be configured as SYNCIN via OTP by setting OTP_MODE_SYNCINB = 0.

SYNCIN can be used to synchronize the FS5600 to an external clock source. The FS5600 can use either the

internal high frequency oscillator or the SYNCIN pin as its source based on the validity of the external clock.

FS5600

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

Product data sheet

Rev. 4 — 29 April 2024

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