DS1085Z-50 Maxim Integrated Products, DS1085Z-50 Datasheet - Page 5

• Manufacturer Part Number: DS1085Z-50
• Description: Timers & Support Products EconOscillator Frequ requency Synthesizer
• Manufacturer: Maxim Integrated Products

REGISTER FUNCTIONS
The user-programmable registers can be used to determine the mode of operation (MUX), operating
frequency (DAC, OFFSET, DIV), and bus settings (ADDR). The functions of the registers are described
in this section, but details of how these registers are programmed can be found in a later section. The
register settings are nonvolatile, with the values being stored automatically or as required in EEPROM
when the registers are programmed through the SDA and SCL pins.
DAC WORD
X = Don’t care.
The DAC word (d0–d9) controls the frequency of the master oscillator. The resolution of this register
depends on the step size of the device. The absolute frequency of the device also depends on the value of
the OFFSET register (see Table 5 and 6).
Table 5. DEFAULT DAC SETTINGS
For any given value of OFFSET the master oscillator frequency can be derived as follows:
where: Min frequency is the lowest frequency shown in Table 6 for the corresponding offset.
OFFSET BYTE
X = Don’t care.
The OFFSET byte (O0–O4) determines the range of frequencies that can be obtained within the absolute
minimum and maximum range of the oscillator. Correct operation of the device is not guaranteed for
values of OFFSET not shown in Table 6.
MSB
d9
MSB
X
Frequency
97.1MHz
d8
DAC is the value of the DAC register (0–1023).
Step size is the step size of the device (10kHz, 25kHz, or 50kHz).
OS is the decimal, integer value of the five MSBs of the RANGE register.
DS1085Z-10
d7
X
(Address 0Eh)
(Address 08h)
DAC
First Data Byte
500
d6
d5
X
Offset
OS
Frequency = Min Frequency + DAC x Step Size
d4
Frequency
104.6MHz
d3
O4
LSB
DS1085Z-25
d2
5 of 21
MSB
DAC
d1
O3
600
d0
Offset
OS
X
O2
Second Data Byte
Frequency
101.8MHz
X
X
O1
DS1085Z-50
X
DAC
500
X
O0
Offset
OS
LSB
X
LSB