Datasheet

AD5174
Rev. B | Page 14 of 20
SHUTDOWN MODE
The AD5174 can be shut down by executing the software
shutdown command, Command 9 (see Tabl e 6), and setting
the LSB to 1. This feature places the RDAC in a zero-power-
consumption state where Terminal A is open circuited and
the wiper terminal, W, remains connected. It is possible to
execute any command from Tabl e 6 while the AD5174 is 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 6).
RESET
The AD5174 can be reset through software by executing Com-
mand 4 (see Table 6). 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 7. Write and Read to RDAC and 50-TP Memory
DIN SDO
1
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 the last programmed 50-TP memory monitor location.
0x0000 0xXX19
NOP Instruction 0 sends a 16-bit word out of SDO, where the six LSBs (that is, last six bits) contain the binary address of
the last programmed 50-TP memory location, for example, 0x19 (see Table 10).
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 C2 = 1, the fuse program command was successful.
1
X is don’t care.
Table 8. Control Register Bit Map
D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 0 0 0 C2 0 C1 C0
Table 9. 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
1 = allow update of wiper position through digital interface
C2 50-TP memory program success bit
0 = fuse program command was unsuccessful (default)
1 = fuse program command was successful
1
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.