Preliminary Technical Data

AD5933

Rev. PrA | Page 13 of 20

CONTROL REGISTER

The AD5933 contains a 16 bit control register (address 80h and

81h) that set the AD5933 control modes. The five MSB’s of the

control register are decoded to provide control functions for

frequency sweep, power down and various other control

functions, defined in Table below. The other command

functions of the control register are explained on the following

pages.

Note: For error checking on the control register it is advised to

write one byte at a time with PEC enabled. This allows full error

checking to be completed before the control register is updated

and therefore ensures the control is not updated with incorrect

data. The Control register will power-up in the following state

xA000h (i.e. in Power-down)

Table 6. Control Register Map

Bit

D15

D15

D14

D13

D12

D11

FREQUENCY SWEEP

D14

0

0

0

0

0

No Operation/ Exit Fuse Blow Mode

D13

0

0

0

0

1

Initialize Sensor with Start Frequency

D12

0

0

0

1

0

Start Frequency Sweep

D11

0

0

0

1

1

Increment Frequency

0

0

1

0

0

Repeat Frequency

0

1

0

0

0

Reserved.

0

1

0

0

1

Measure Temperature

0

1

0

1

0

Power Down

0

1

0

1

1

Standby Mode

D10

External Calibration Mode = “1”

D9

D9

D8

Output Voltage

D8

0

0

No Divide.

(Normal Mode = 2.0V)

0

1

Divide by 10

(200mv)

1

0

Divide by 5

(400mv)

1

1

Divide by 2

(1.0v)

D7

Post Gain

“0” = Multiply X 5;

“1” = Multiply X 1.

D6

Error Checking Enable = “1”; Disable=”0”

D5

Reserved. Set to “0”

D4

RESET

D3

D3

D2

System Clock

D2

0

0

Internal Oscillator

0

1

Reserved.

1

0

External Oscillator

1

1

PLL

D1

0

RESERVED

D0

0

RESERVED