ACE5372 datasheet(19/29 Pages) ACE

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ACE5372

Technology

Low Power Real-Time Clock (RTC)

VER 1.2

Configuration of Oscillating Circuit

Because the adjustment of crystal oscillator frequency is also the adjustment of clock frequency, so the

former adjustment can be done through CIN & COUT on the both sides of crystal.

ACE5372 clock cooperates with CIN & COUT, so oscillator frequency can be referred to crystal CL.

General, relation between CL and CIN or COUT is as follows：

CS：Board floating capacitance

If crystal oscillator frequency is on the higher side, the CL should be decreased, contrarily, the CL should

be increased.

According to this standard, the best CL is chosen to adjust frequency and clock frequency. For example:

if the frequency is on the higher side, it can be lowed by attaching a CGOUT capacitor.

*CGOUT＝0~15pF

Time Trimming Circuit

Using the time trimming circuit gain or lose of clock may be adjusted with high precision by changing

clock pulses for one second every 20 seconds.

1.When oscillation frequency *1 > target frequency*2（clock gain）

Adjustment amount*3

= (Oscillation frequency – Target frequency) x 10 +1

*1) Oscillation frequency: Clock frequency output from the

⎯INTRB pin

*2) Target frequency: TYP. 32.768KHz to 32.000KHz

*3) Adjustment amount: A value to be set finally to F6 to F0 bits. This value is expressed in 7 bit binary

digits with sign bit (two’s compliment).

Cout

Cin

Cout

Cin

ACE5372

)

arg

(

)

arg

(

etFrequenc

nFrequency

Oscillatio

etFrequenc

Frequency

Oscilation

−

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