Datasheet

level sensitive). Successful reading of the alert
response address clears the interrupt latch.
Command Byte Functions
The 8-bit command byte register (Table 4) is the master
index that points to the various other registers within the
MAX1668/MAX1805/MAX1989. The register’s POR
state is 0000 0000, so that a receive byte transmission
(a protocol that lacks the command byte) that occurs
immediately after POR returns the current local temper-
ature data.
MAX1668/MAX1805/MAX1989
†
Multichannel Remote/Local
Temperature Sensors
12 ______________________________________________________________________________________
Table 4. Command Byte Bit Assignments for MAX1668/MAX1805/MAX1989
*If the device is in hardware standby mode at POR, all temperature registers read 0°C.
**Not available for MAX1805.
REGISTER COMMAND POR STATE FUNCTION
RIT 00h 0000 0000* Read local temperature
RET1 01h 0000 0000* Read remote DX1 temperature
RET2 02h 0000 0000* Read remote DX2 temperature
RET3** 03h 0000 0000* Read remote DX3 temperature
RET4** 04h 0000 0000* Read remote DX4 temperature
RS1 05h 0000 0000 Read status byte 1
RS2 06h 0000 0000 Read status byte 2
RC 07h 0000 0000 Read Configuration Byte
RIHL 08h 0111 1111 Read local T
HIGH
limit
RILL 09h 1100 1001 Read local T
LOW
limit
REHL1 0Ah
0111 1111
(0110 1110)
Read remote DX1 T
HIGH
limit (MAX1989)
RELL1 0Bh 1100 1001 Read remote DX1 T
LOW
limit
REHL2 0Ch 0111 1111 Read remote DX2 T
HIGH
limit
RELL2 0Dh 1100 1001 Read remote DX2 T
LOW
limit
REHL3** 0Eh 0111 1111 Read remote DX3 T
HIGH
limit
RELL3** 0Fh 1100 1001 Read remote DX3 T
LOW
limit
REHL4** 10h 0111 1111 Read remote DX4 T
HIGH
limit
RELL4** 11h 1100 1001 Read remote DX4 T
LOW
limit
WC 12h N/A Write configuration byte
WIHL 13h N/A Write local T
HIGH
limit
WILL 14h N/A Write local T
LOW
limit
WEHI1 15h N/A Write remote DX1 T
HIGH
limit
WELL1 16h N/A Write remote DX1 T
LOW
limit
WEHI2 17h N/A Write remote DX2 T
HIGH
limit
WELL2 18h N/A Write remote DX2 T
LOW
limit
WEHI3** 19h N/A Write remote DX3 T
HIGH
limit
WELL3** 1Ah N/A Write remote DX3 T
LOW
limit
WEHI4** 1Bh N/A Write remote DX4 T
HIGH
limit
WELL4** 1Ch N/A Write remote DX4 T
LOW
limit
MFG ID FEh 0100 1101 Read manufacture ID
DEV ID FFh
0000 0011 (0000 0101)
[0000 1011]
Read device ID (for MAX1805) [for MAX1989]