MAS6505 datasheet(26/44 Pages) MAS

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DA6505.005

11 June 2018

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CLOCK OSCILLATOR FREQUENCY TRIM REGISTER (FF/7FHEX)

Note that the internal clock oscillator frequency has

been factory trimmed and the trim value has been

stored

into

the

EEPROM

(BF/3FHEX).

recommended

not

change

the

factory

programmed value! See table 11.

The

Clock

oscillator

frequency

trim

(FF/7FHEX) is for trimming the internal clock oscillator

to 250 kHz frequency. By selecting ENTP=1 in the

Clock oscillator frequency trim register (FF/7FHEX)

and STEST=0001 and TRIM=11 in the Trim and test

all the time and the 250 kHz oscillator signal can be

measured at the SDO pin and also adjusted by the

Clock oscillator frequency trim register.

The seven LSB bits adjust the oscillator signal period

in 35 ns steps. The signal period decreases and

frequency increases when the trim value increases.

The seven bits

complement number. Typically the mid value 00HEX

corresponds to 212 kHz clock oscillator frequency.

After finding a suitable trim value it can be stored into

the EEPROM (BF/3FHEX).

Table 11. Clock oscillator frequency trim register (FF/7FHEX)

Bit

Number

Bit

Name

Description

Value

(bin)

Value

(2’s complement)

Value

(dec)

Function

ENTP

Enable for

test pin

Disable test pin (default)

SDO is test pin if STEST<>0

6-0

OSCF

Clock

oscillator

frequency

control

0111111

0111110

…….

0000001

0000000

1111111

1111110

…….

1000001

1000000

…

-1

-2

…

-63

-64

…

127

126

…

Max frequency

…

212 kHz

…

Min frequency

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