FN6659 datasheet(18/32 Pages) RENESAS

18 / 32 page

ISL12022

FN6659 Rev.3.01

Page 18 of 32

Oct 24, 2019

trimming uses load capacitance adjustment to pull the oscillator

frequency. A range of +62.5ppm to -61.5ppm is possible with

combined digital and analog trimming.

AGING AND INITIAL TRIM DIGITAL TRIMMING BITS

(IDTR0<1:0>)

These bits allow ±30.5ppm initial trimming range for the crystal

frequency. This is meant to be a coarse adjustment if the range

needed is outside that of the IATR control. See Table 10. The

IDTR0 register should only be changed while the TSE (Temp

Sense Enable) bit is “0”.

AGING AND INITIAL ANALOG TRIMMING BITS

(IATR0 <5:0>)

The analog trimming register allows +32ppm to -31ppm

adjustment in 1ppm/bit increments. This enables fine frequency

adjustment for trimming initial crystal accuracy error or to correct

for aging drift. The IATR0 register should only be changed while the

TSE (Temp Sense Enable) bit is “0”.

Aging adjustment is normally a few ppm and can be handled by

writing to the IATR section.

TABLE 10. IDTR0 TRIMMING RANGE

IDTR01

IDTR00

TRIMMING RANGE

Default/Disabled

+30.5ppm

0ppm

-30.5ppm

TABLE 11. INITIAL AT AND DT SETTING REGISTER

ADDR

321

0Bh

IDTR01 IDTR00 IATR05 IATR04 IATR03 IATR02 IATR01 IATR00

TABLE 12. IATR0 TRIMMING RANGE

IATR05 IATR04 IATR03 IATR02 IATR01 IATR00

TRIMMING

RANGE

0000

+32

0001

+31

0010

+30

0011

+29

0100

+28

0101

+27

0110

+26

0111

+25

1000

+24

1001

+23

1010

+22

1011

+21

1100

+20

1101

+19

001110

+18

001111

+17

010000

+16

010001

+15

010010

+14

010011

+13

010100

+12

010101

+11

010110

+10

010111

011000

011001

011010

011011

011100

011101

011110

011111

100000

100001

-1

100010

-2

100011

-3

100100

-4

100101

-5

100110

-6

100111

-7

101000

-8

101001

-9

101010

-10

101011

-11

101100

-12

101101

-13

101110

-14

101111

-15

110000

-16

110001

-17

110010

-18

110011

-19

110100

-20

TABLE 12. IATR0 TRIMMING RANGE (Continued)

IATR05 IATR04 IATR03 IATR02 IATR01 IATR00

TRIMMING

RANGE

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