
AD5930
This is beneficial for applications where the user needs to burst 
a frequency for a set period, and then “l(fā)isten” for a response 
before increasing to the next frequency. Note also that the 
beginning of each frequency increment is at midscale (Phase 0 
Rad). Therefore, the phase of the signal is always known. 
Rev. 0 | Page 17 of 28 
To set up the AD5930 in burst mode, the CW/BURST bit (D7) 
in the control register must be set to 1. See the Activating and 
Controlling the Sweep section for more details about the burst 
output mode. 
SERIAL INTERFACE 
The AD5930 has a standard 3-wire serial interface, which is 
compatible with SPI, QSPI, MICROWIRE, and DSP 
interface standards. 
Data is loaded into the device as a 16-bit word under the 
control of a serial clock input, SCLK. The timing diagram for 
this operation is given in Figure 4.  
The FSYNC input is a level-triggered input that acts as a frame 
synchronization and chip enable. Data can only be transferred 
into the device when FSYNC is low. To start the serial data 
transfer, FSYNC should be taken low, observing the minimum 
FSYNC to SCLK falling edge setup time, t
7
. After FSYNC goes 
low, serial data is shifted into the device's input shift register on 
the falling edges of SCLK for 16 clock pulses. FSYNC can be 
taken high after the 16
th
 falling edge of SCLK, observing the 
minimum SCLK falling edge to FSYNC rising edge time, t
8. 
Alternatively, FSYNC can be kept low for a multiple of 16 SCLK 
pulses, and then brought high at the end of the data transfer. In 
this way, a continuous stream of 16-bit words can be loaded while 
FSYNC is held low. FSYNC should only go high after the 16th 
SCLK falling edge of the last word is loaded.  
The SCLK can be continuous, or, alternatively, the SCLK can 
idle high or low between write operations. 
POWERING UP THE AD5930 
When the AD5930 is powered up, the part is in an undefined 
state, and therefore, must be reset before use. The eight registers 
(control and frequency) contain invalid data and need to be set 
to a known value by the user. The control register should be the 
first register to be programmed, as this sets up the part. Note 
that a write to the control register automatically resets the 
internal state machines and provides an analog output of 
midscale as it provides the same function as the INTERRUPT 
pin. Typically, this is followed by a serial loading of all the 
required sweep parameters. The DAC output remains at 
midscale until a sweep is started using the CTRL pin.  
PROGRAMMING THE AD5930 
The AD5930 is designed to provide automatic frequency sweeps 
when the CTRL pin is triggered. The automatic sweep is 
controlled by a set of registers, the addresses of which are given 
in Table 5. The function of each register is described in more 
detail in the following section. 
Table 5. Register Addresses 
Register Address 
D15 
D14 
D13 
D12 
Mnemonic 
0 
0 
0 
0 
C
REG
0 
0 
0 
1 
N
INCR
Name 
Control bits 
Number of 
increments  
Lower 12 bits of delta 
frequency 
Higher 12 bits of 
delta frequency 
Increment interval 
Burst interval 
Lower 12 bits of start 
frequency 
Higher 12 bits of start 
frequency 
Reserved 
Reserved 
0 
0 
1 
0 
f 
0 
0 
1 
1 
f 
0 
1 
1 
1 
0 
1 
0 
0 
t
INT
T
BURST
F
START
1 
1 
0 
1 
F
START
1 
1 
The Control Register 
The AD5930 contains a 12-bit control register (see Table 6) that 
sets up the operating modes of the AD5930. The different 
functions and the various output options from the AD5930 are 
controlled by this register.  
1 
1 
1 
1 
0 
1 
Table 7 describes the individual bits of the control register.  
To address the control register, D15 to D12 of the 16-bit serial 
word must be set to 0. 
Table 6. Control Register 
D15 
D14 
D13 
D12 
0 
0 
0 
0 
D11 to D0 
Control Bits