AD5259

Data Sheet

Rev. C | Page 18 of 24

TOLERANCE READBACK MODES

Table 15. Traditional Readback of Tolerance (Individually)

S

7-Bit Device Address

(See Table 5)

0 SA 0 0 1 1 1 1 1 0 SA S

7-Bit Device Address

(See Table 5)

1 SA D7 D6 D5 D4 D3 D2 D1 D0 NA P

Slave Address Byte

Instruction Byte

Slave Address Byte

Sign + Integer Byte

↑

Repeat start

S

7-Bit Device Address

(See Table 5)

0 SA 0 0 1 1 1 1 1 1 SA S

7-Bit Device Address

(See Table 5)

1 SA D7 D6 D5 D4 D3 D2 D1 D0 NA P

Slave Address Byte

Instruction Byte

Slave Address Byte

Decimal Byte

↑

Repeat start

Table 16.Traditional Readback of Tolerance (Consecutively)

S

7-Bit Device

Address

(See Table 5)

0 SA 0 0 1 1 1 1 1 0 SA S

7-Bit Device

Address

(See Table 5)

1 SA D7 D6 D5 D4 D3 D2 D1 D0 MA D7 D6 D5 D4 D3 D2 D1 D0 NA P

Slave Address

Byte

Instruction Byte

Slave Address

Byte

Sign + Integer Byte

Decimal Byte

↑

Repeat start

A

A

A

D7

D6

D5

D4

D3

D2

D1

D0

SIGN

SIGN

7 BITS FOR INTEGER NUMBER

D7

D6

D5

D4

D3

D2

D1

D0

8 BITS FOR DECIMAL NUMBER

Figure 41. Format of Stored Tolerance in Sign Magnitude Format with Bit Position Descriptions.

(Unit is Percent. Only Data Bytes are Shown.)

nonvolatile memory. The tolerance is stored in the memory

during factory production and can be read by users at any time.

The knowledge of stored tolerance allows users to accurately

mode, and open-loop applications where knowledge of abso-

lute resistance is critical.

The stored tolerance resides in the read-only memory and is

expressed as a percentage. The tolerance is stored in two memory

location bytes in sign magnitude binary form (see Figure 41).

The two EEPROM address bytes are 11110 (sign + integer)

and 11111 (decimal number). The two bytes can be indi-

vidually accessed with two separate commands (see Table 15).

Alternatively, readback of the first byte followed by the second

byte can be done in one command (see Table 16). In the latter

case, the memory pointer will automatically increment from

the first to the second EEPROM location (increments from

11110 to 11111) if read consecutively.

In the first memory location, the MSB is designated for the

sign (0 = + and 1= −) and the seven LSBs are designated for

the integer portion of the tolerance. In the second memory

location, all eight data bits are designated for the decimal

portion of tolerance. Note the decimal portion has a limited

and the data readback from Address 11110 shows 0001 1100,

and Address 11111 shows 0000 1111, then the tolerance can

be calculated as

MSB: 0 = +

Next 7 MSB: 001 1100 = 28

Tolerance = +28.06%

Rounded Tolerance = +28.1% and therefore,