AD9834 Analog Devices, AD9834 Datasheet - Page 15

• Manufacturer Part Number: AD9834
• Description: +2.5V to +5.5V, 50MHz, Low Power (25mW) Complete DDS With on Board Comparator in 20-pin Tssop Package
• Manufacturer: Analog Devices

REV PrL
YES
YES
(CONTROL REGISTER WRITE)
V OUT = V REFOUT * 18 * R LOAD /R SET * (1+ (SIN(2p(FREQREG * F MCLK * t/2 28 + PHASEREG/2 12 )))
PRELIMINARY TECHNICAL DATA
CHANGE FSEL/
PSEL = Selected Phase Register
FSELECT?
(CONTROL REGISTER WRITE)
FSEL = Selected Freq Register
CHANGE FREQ
Figure 7. Flow Chart for AD9834 Initialisation and Operation
REGISTER?
REGISTER
PIN/SW = 0
CONTROL
RESET = 1
WRTE?
USING CONTROL
WRITE TO FREQUENCY AND PHASE REGISTERS
USING CONTROL
NO
RESET bit = 0
PIN/SW = 0
BIT
PHASE 0 & PHASE1 REG = (PhaseShift * 2 12 ) / 2p
BIT
YES
YES
YES
FREQ0 REG = F OUT0 / f MCLK * 2 28
FREQ1 REG = F OUT1 / f MCLK * 2 28
SELECT FREQUENCY REGISTERS
SELECT PHASE REGISTERS
INITIALISATION
APPLY RESET
CHANGE FREQUENCY?
CHANGE DAC OUTPUT
See Timing Diagram Fig. 2
CHANGE OUTPUT AT
CHANGE PHASE?
FROM SIN TO RAMP?
(See Figure 9 Below)
SIGN BIT OUT PIN?
Figure 8. Initialisation
WAIT 7/8 MCLK
DAC OUTPUT
SET RESET = 0
SELECT DATA
DATA WRITE
See Figure 9
SOURCES
See Figure 10
CYCLES
(CONTROL REGISTER WRITE)
NO
NO
NO
–15–
NO
PSELECT = Selected Phase Register
FSELECT = Selected Freq Register
USING PIN
(APPLY SIGNALS AT PINS)
PIN/SW = 1
USING PIN
YES
RESET pin = 0
CHANGE PHASE
CHANGE PSEL/
INITIALISATION
See Figure 8 below
PSELECT?
REGISTER?
YES
NO
SET RESET PIN = 1
YES
AD9834