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AD5270/AD5271 Data Sheet

Rev. F | Page 20 of 24

SHUT-DOWN MODE

The AD5270/AD5271 can be shut down by executing the

software shutdown command, Command 9 (see Table 11), and

setting the LSB to 1. This feature places the RDAC in a zero-

power-consumption state where Terminal Ax is open circuited

and the Wiper Terminal Wx remains connected. It is possible to

execute any command from Table 11 while the AD5270/AD5271

are in shutdown mode. The parts can be taken out of shutdown

mode by executing Command 9 and setting the LSB to 0 or by a

software reset, Command 4 (see Table 11).

RESISTOR PERFORMANCE MODE

This mode activates a new, patented 1% end-to-end resistor

tolerance that ensures a ±1% resistor tolerance error on each

code, that is, code = half scale, R

= 10 kΩ ± 100 Ω. See Table 2,

Table 3, Table 5, and Table 6 to verify which codes achieve ±1%

resistor tolerance. The resistor performance mode is activated by

programming Bit C2 of the control register.

RESET

The AD5270/AD5271 can be reset through software by executing

Command 4 (see Table 11). The reset command loads the

RDAC register with the contents of the most recently programmed

50-TP memory location. The RDAC register loads with

midscale if no 50-TP memory location has been previously

programmed.

Table 12. Write and Read to RDAC and 50-TP Memory

DIN SDO

Action

0x1C03 0xXXXX Enable update of the wiper position and the 50-TP memory contents through the digital interface.

0x0500 0x1C03 Write 0x100 to the RDAC register; wiper moves to ¼ full-scale position.

0x0800 0x0500 Prepares data read from RDAC register.

0x0C00 0x100 Stores RDAC register content into the 50-TP memory. A 16-bit word appears out of SDO, where the last 10-bits contain

the contents of the RDAC register (0x100).

0x1800 0x0C00 Prepares data read of last programmed 50-TP memory monitor location.

0x0000 0xXX19 NOP Instruction 0 sends a 16-bit word out of SDO, where the six LSBs last six bits contain the binary address of the last

programmed 50-TP memory location, for example, 0x19 (see Table 13).

0x1419 0x0000 Prepares data read from Memory Location 0x19.

0x2000 0x0100 Prepares data read from the control register. Sends a 16-bit word out of SDO, where the last 10-bits contain the

contents of Memory Location 0x19.

0x0000 0xXXXX NOP Instruction 0 sends a 16-bit word out of SDO, where the last four bits contain the contents of the control register.

If Bit C3 = 1, the fuse program command successful.

X is don’t care.

Table 13. Control Register Bit Map

DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0

0 0 0 0 0 0 C3 C2 C1 C0

Table 14. Control Register Bit Description

Bit Name Description

C0 50-TP program enable

0 = 50-TP program disabled (default)

1 = enable device for 50-TP program

C1 RDAC register write protect

0 = wiper position frozen to value in 50-TP memory (default)

1 = allow update of wiper position through digital interface

C2 R-performance enable

0 = RDAC resistor tolerance calibration enabled (default)

1 = RDAC resistor tolerance calibration disabled

C3 50-TP memory program success bit

0 = fuse program command unsuccessful (default)

1 = fuse program command successful

Wiper position frozen to the last value programmed in the 50-TP memory. The wiper is frozen to midscale if the 50-TP memory has not been previously programmed.