RV-3029 Datasheet, PDF (36/67 Pages) MICORO CRYSTAL SWITZERLAND – DTCXO Temperature Compensated Real Time Clock

Micro Crystal
DTCXO Temperature Compensated Real Time Clock / Calendar Module
RV-3029
4.9. CLOCK OUTPUT CLKOUT
The internal reference frequency is generated by the oscillator-circuitry operating a 32.768 kHz “Tuning-Fork”
Quartz Crystal.
A programmable square wave is available at CLKOUT pin. Frequencies of 32.768 kHz, 1024 Hz, 32 Hz or 1 Hz can
be generated for use as a system clock, microcontroller clock, input to a charge pump or for test purposes.
The duty cycle of the selected clock is not controlled. However, due to the nature of the clock generation, all
frequencies will be 50:50 except the 32.768 kHz.
The frequency 32.768 kHz is clocked directly from the oscillator-circuitry, as a consequence of that, this frequency
does not contain frequency compensation clock pulses. The frequencies 1024 / 32 / 1 Hz are clocked from the
prescaler and contain frequency compensation clock pulses.
Operation is controlled by the bits “FD1” / “FD0” (bit 2 & 3 in the register EEPROM Control).
If “Clk/Int” is = “1” (bit 7 in register Control_1), CLKOUT pin becomes a push-pull CLKOUT output and can be
enabled / disabled with the CLKOE pin. When disabled with CLKOE pin = “low”, the CLKOUT output is pulled low.
Register EEPROM Control FD0 / FD1 CLKOUT Frequency Selection (address 30Eh…bits description)
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3 Bit 2 Bit 1
Bit 0
30h
EEPROM Control
R80k
R20k
R5k
R1k
FD1
FD0
ThE
1
Bit
3 to 2
3
2
CLKOUT Frequency Typ. Duty Cycle
FD1
FD0
[Hz]
%¹⁾
Remarks
0
0
0
1
32768
1024
40:60 to 60:40
50:50
Directly from 32.768kHz oscillator
circuitry, without freq. compensation
With frequency compensation
1
0
32
50:50
With frequency compensation
1
1
1
50:50
With frequency compensation
1) _{Duty cycle definition: % HIGH-level time : % LOW-level time}
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