ADN2860-EVAL AD [Analog Devices], ADN2860-EVAL Datasheet - Page 14

• Manufacturer Part Number: ADN2860-EVAL
• Description: 3-Channel Digital Potentiometer with Nonvolatile Memory
• Manufacturer: AD [Analog Devices]

ADN2860
RDAC Shortcut Commands
Eleven shortcut commands are provided for easy manipulation
of RDAC registers and their corresponding EEPROM memory
locations. These commands are shown in Table 9. A more
detailed discussion about the RDAC shortcut commands can be
found in the Theory of Operation section.
The interface for issuing an RDAC shortcut command is shown
in Figure 25. All shortcut commands require acknowledge
polling to determine whether the command has finished
executing.
Table 8. Addresses for Reading Tolerance (CMD/ REG = 0, EE/ RDAC = 1, A4 = 1)
A4
1
1
1
1
1
1
A
SIGN
SIGN
D7
A3
1
1
1
1
1
1
D6
2
6
0
0
0
0
1
1
A2
Figure 26. Format of Stored Tolerance in Sign Magnitude with Bit Position Descriptions (Unit is in %, Only Data Bytes Shown)
D5
2
5
A1
0
0
1
1
0
0
7 BITS FOR INTEGER NUMBER
D4
2
4
A0
0
1
0
1
0
1
D3
2
3
Sign and 7-bit integer values of RDAC0 tolerance (read only)
8-bit decimal value of RDAC0 tolerance (read only)
Sign and 7-bit integer values of RDAC1 tolerance (read only)
8-bit decimal value of RDAC1 tolerance (read only)
Sign and 7-bit integer values of RDAC2 tolerance (read only)
8-bit decimal value of RDAC2 tolerance (read only)
Data Byte Description
D2
2
2
D1
2
1
D0
2
Rev. A | Page 14 of 20
0
A
RDAC Resistor Tolerance
The end-to-end resistance tolerance for each RDAC channel is
stored in read-only memory during factory production. This
information is read by using the address and bits specified in
Table 8.
Tolerance values are stored in percentage form. Figure 26 shows
the format of the tolerance data stored in memory. Each stored
tolerance uses two memory locations. The first location stores
the integer portion, while the second location stores the decimal
portion.
The resistance tolerance is stored in sign-magnitude format.
The MSB of the first memory location designates the sign
(0 = +, 1 = −) and the remaining 7 LSBs are designated for the
integer portion of the tolerance. All eight bits of the second
memory location are represented by the decimal portion of the
tolerance value.
2
D7
–1
2
D6
–2
2
D5
8 BITS FOR DECIMAL NUMBER
–3
2
D4
–4
2
D3
–5
D2
2
–6
2
D1
–7
2
D0
–8
A