will dither between 2MHz and 1.96MHz at a modulation

frequency determined by the selected dither frequen-

cy. Continuing with the same example, if D1 and D0

frequency would be 15.625kHz.

2-Wire Slave Address

The 2-wire serial interface is used to read and write the

control registers of the DS1094L. The default slave

address of the DS1094L is B0h (see Figure 4). Using

the 3 address bits (A2, A1, and A0) in the ADDR regis-

ter, the slave address can be changed to allow as

many as eight DS1094Ls reside on the same 2-wire

bus or to simply prevent address conflicts with other 2-

wire devices. The location of the address bits within the

ADDR register is shown in the Control Registers sec-

tion. A detailed description of the 2-wire interface is

found in the 2-Wire Serial Interface Description section.

EEPROM Write Control

Since EEPROM does have a limited number of lifetime

write cycles (specified in the NONVOLATILE MEMORY

CHARACTERISTICS electrical table), it is possible to

configure the DS1094L to prevent EEPROM wear out

and eliminate the EEPROM write cycle time by using

the WC bit in the ADDR register. When the WC bit is 0

(default), register writes are automatically written into

EEPROM. The Write EE Command is not needed.

However, if WC = 1, then register writes are stored in

SRAM and only written to EEPROM when the user

sends the Write EE Command. If power to the device is

cycled, the last value stored in EEPROM is recalled.

The time required to store the values is one EEPROM

write cycle time. WC = 1 is ideal for applications that

frequently modify the frequency/registers.

Regardless of the value of the WC bit, the value of the

ADDR register is always written immediately to EEP-

ROM.

Control Registers

The DS1094L control registers are used to program the

frequency and features of the device. Table 6 lists the

DS1094L’s control registers and illustrates bit locations

as well as other valuable information. The memory

address of each register is shown in the ADDRESS col-

umn. The factory default values programmed into EEP-

ROM are shown in the DEFAULT column. Refer to the

corresponding sections to determine what values to

write to the registers.

PRESCALER (02h)

D1, D0

Selects the dither frequency. Refer to Table 5.

Ph1, Ph0 Determines whether the two-phase, three-

phase, or four-phase mode is selected. Refer

to Table 3.

J1, J0

Selects the dither amount. Refer to Table 4.

P1, P0

Determines the prescaler value. Refer to

Table 2.

DAC (08h)

D3 to D0 This four-bit value determines the master oscil-

the Master Oscillator section for a detailed

information on calculating the DAC value.

ADDR (0Dh)

WC

The EEPROM write control bit determines if

writes to control registers are automatically

backed up in NV memory (EEPROM) or

whether a write EE command is required to

write to NV memory. See the EEPROM Write

Control section for more information.

A2 to A0 This three-bit value determines the 2-wire

slave address.

WRITE EE COMMAND (3Fh)

This command can be used when the WC bit = 1 (see

explanation in the EEPROM Write Control section) to

transfer registers internally from SRAM to EEPROM. The

time required to store the values is one EEPROM write

cycle time. This command is not needed if WC = 0.

Multiphase Spread-Spectrum EconOscillator

8

_____________________________________________________________________

BINARY

REGISTER

ADDRESS

MSB

LSB

DEFAULT

ACCESS

PRESCALER

02h

D1

D0

Ph1

Ph0

J1

J0

P1

P0

11001101b

R/

W

DAC

08h

D3

D2

D1

D0

XXXX0000b

R/

W

ADDR

0Dh

WC

A2

A1

A0

XXXX0000b

R/

W

WRITE EE Command

3Fh

No Data

W

Table 6. Control Registers

X = Don’t care