PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
(Not to Scale)
Figure 4. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
Serial Input Register Clock. Shifts in one bit at a time on positive clock edges.
Serial Data Input. Shifts in one bit at a time on positive clock CLK edges. MSB loads first.
Serial Data Output. Serves readback and daisy-chain functions. Command 9 and Command 10 activate the SDO
output for the readback function, delayed by 24 or 25 clock pulses, depending on the clock polarity before and
after the data-word (see Figure 2 and Figure 3). In other commands, the SDO shifts out the previously loaded SDI
bit pattern, delayed by 24 or 25 clock pulses depending on the clock polarity (see Figure 2 and Figure 3). This
previously shifted out SDI can be used for daisy-chaining multiple devices. Whenever SDO is used, a pull-up
resistor in the range of 1 kΩ to 10 kΩ is needed.
Ground Pin, Logic Ground Reference.
Negative Supply. Connect to 0 V for single-supply applications. If VSS is used in dual supply, it must be able to sink
2 mA for 15 ms when storing data to EEMEM.
Terminal A of RDAC1.
Wiper terminal of RDAC1. ADDR (RDAC1) = 0x0.
Terminal B of RDAC1.
Terminal B of RDAC2.
Wiper terminal of RDAC2. ADDR (RDAC2) = 0x1.
Terminal A of RDAC2.
Positive Power Supply.
Optional Write Protect. When active low, WP prevents any changes to the present contents, except PR strobe.
CMD_1 and COMD_8 refresh the RDAC register from EEMEM. Tie WP to VDD, if not used.
Optional Hardware Override Preset. Refreshes the scratchpad register with current contents of the EEMEM
register. Factory default loads midscale until EEMEM is loaded with a new value by the user. PR is activated
at the logic high transition. Tie PR to VDD, if not used.
Serial Register Chip Select Active Low. Serial register operation takes place when CS returns to logic high.
Ready. Active high open-drain output. Identifies completion of Instruction 2, Instruction 3, Instruction 8,
Instruction 9, Instruction 10, and PR.
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