AD5522

Preliminary Technical Data

Rev. PrL | Page 28 of 45

WRITE SYSTEM CONTROL REGISTER

The System Control Register is accessed when the PMU channel address PMU3-PMU0 and Mode Bits, MODE1 and MODE0 are all

zeros. It allows quick setup of different functions within the device. The System Control Register operates on a per device basis.

Table 15. System Control Register Bits

B28

B27

B26

B25

B24

B23

B22

B21

B20

B19

B18

B17

B16

B15

B14

B13

B12

B11

B10

B9

B8

B7

B6

B5

B4

B3

B2

B1/0

Table 16. System Control Register Functions

Bit

Bit name

Description

28

(MSB)

RD/WR

When low, a write function takes place to the selected register, while if the RD/WR bit is set high, this initiates a readback sequence

of PMU, Alarm, Comparator, System Control or DAC register as determined by address bits.

27

PMU3

26

PMU2

25

PMU1

24

PMU0

Bits PMU3 through PMU0 address each of the PMU channels in the device. If all four of this bits are set to zero, the System Control

Register is addressed.

B27

B26

B25

B24

B23

B22

SELECTED REGISTER

PMU3

PMU2

PMU1

PMU0

MODE1

MODE0

CH3

CH2

CH1

CH0

0

0

0

0

0

0

Write to System Control Register

0

0

0

1

×

×

×

CHO

0

0

1

0

×

×

CH1

×

0

0

1

1

×

×

CH1

CH0

0

1

0

0

×

CH2

×

×

-

-

-

-

-

-

-

-

1

0

0

0

CH3

×

×

×

-

-

-

-

-

-

-

-

1

1

1

0

CH3

CH2

CH1

×

1

1

1

1

Select DAC or PMU Registers.

See below

CH3

CH2

CH1

CH0

23

MODE1

22

MODE0

Mode Bits, MODE0 and MODE1 allow addressing of the PMU register or the DAC gain (m), offset (c ) or input register (x1). Set to

Zero to access the System Control Register.

MODE1

MODE0

Action

0

0

System Control Register or PMU Register

0

1

DAC Gain (m) Register

1

0

DAC Offset (c) Register

1

1

DAC Input Data Register, (x1)

SYSTEM CONTROL REGISTER SPECIFIC BITS

21

CL3

20

CL2

19

CL1

18

CL0

Clamp Enable. Bits CL3 through CL0 enable and disable the clamp function per channel. A “0” disables, while a “1” enables. The

clamp enable function is also available in the PMU register on a per channel basis. This dual functionality allows flexible enable or

disabling of this function. When reading back information on the status of the clamp enable function, what was most recently

written to the clamp register is available in the readback word from either PMU or System Control Registers.

17

CPOLH3

16

CPOLH2

15

CPOLH1

14

CPOLH0

Comparator Output Enable. By default the comparator outputs are hi-Z on power on. A “1” in each bit position enables the

comparator output for the selected channel. The CPBIASEN (Bit 13) must be enabled to power on the comparator functions. The

comparator enable function is also available in the PMU register on a per channel basis. This dual functionality allows flexible

enable or disabling of this function. When reading back information on the status of the comparator enable function, what was

most recently written to the comparator register is available in the readback word from either PMU or System Control Registers.

13

CPBIASEN

Comparator Enable. By default the comparators are powered down on power on. To enable the comparator function for all

channels, write a “1” to the CPBIASEN bit. A “0” disabled the comparators and shuts them down. Comparator Output Enables bits

(CPOLHx) allow the user to switch on each comparator output individually, enabling bussing of comparator outputs.

12

DUTGND/CH

DUTGND per channel enable. The GUARDIN(0-3)/DUTGND(0-3) pins are shared pin functions and may be configured to enable a

DUTGND per PMU channel or GUARD input per PMU channel. Setting this bit to “1” enables DUTGND per channel. In this mode, this

pin now functions as a DUTGND pin on a per channel basis. The guard inputs are disconnected from this pin and instead connected

directly to the MEASVH line by an internal connection. Default power on condition is GUARDIN(0-3).

11

GUARD ALM

10

CLAMP ALM

Clamp and Guard Alarm Function share one open drain CGALM alarm pin. By default, the CGALM pin is disabled. Bits GUARD ALM

and CLAMP ALM allow the user to choose if they only wish to have both or either information flagged to the CGALM pin. Set high to

enable either alarm function.

9

INT10K

Internal Sense Short, INT10K. Setting this bit high allows the user to connect in an internal sense short resistor of 10kΩ between the

FOH and the MEASVH lines, (closes SW 7), it also closes SW 15, connecting another 10 kΩ resistor between DUTGND and AGND.