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©2016-2026 Renesas Electronics Corporation

June 2, 2026

5P35021 Datasheet

Digital Spread Spectrum

Figure 6. Digital Spread Spectrum

Down spread or spread off

N = Fvco/Fpfd

Center Spread

N = Nssoff + N × SSamount/2

N: include integer and fraction

Fvco: VCOs frequency

Fpfd: PLLs pfd frequency

Fss: spread modulation rate

SSamount: spread percentage

The black line is for the down spread; N will decrease to make the center frequency is lower than spread off. The blue line is for the center

spread; there is an offset put on divider ratio to make the center frequency keep same as spread off.

Example: 0.5% down spread at 32kHz modulation rate.

VBAT

The 5P35021 supports a low-power operation 32.768kHz RTC clock with only a coin cell battery supply. The coin cell battery power

capacitance is usually 170mAhr or higher, with less than 2μA* low-power DCO operation mode will support application up to few years

clock source for date/time keeping circuit (RTC).

When main power exists (for example, VDD33 and VDDA), the 5P35021 will switch DCO power source to main power to save battery

power.

VBAT needs to be 3.0V–3.3V.

Table 12. VBAT Switching Threshold

VDD33

VBAT

DCO Power Source

> 2.5V

—

VDD33

< 2.3V

—

VBAT

Fout

*

2

Fvco

N



Fss

*

2

Fpfd

period



period

SSamount

*

N

step



VDD33

VBAT

Switch to VBAT

(VDD33 falling down to 2.3V)

Switch to VDD33

(VDD33 raise up to 2.5V )