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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

AA

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 40. 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 absolute

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 40).

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

11111 (decimal number). The two bytes can be individually

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

that the decimal portion has a limited accuracy of only 0.1%. For

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,