Rainbow Electronics MAX6642 - Manual (Page 8)

MAX6642
(0001 100). Following such a broadcast, any slave
device that generated an interrupt attempts to identify
itself by putting its own address on the bus.
The alert response can activate several different slave
devices simultaneously, similar to the I
2 C General Call.
If more than one slave attempts to respond, bus arbitra-
tion rules apply, and the device with the lower address
code wins. The losing device does not generate an
acknowledge and continues to hold the ALERT line low
until cleared. (The conditions for clearing an ALERT
vary depending on the type of slave device.)
Successful completion of the alert response protocol
clears the interrupt latch. If the condition still exists, the
device reasserts the ALERT interrupt at the end of the
next conversion.
Command Byte Functions
The 8-bit command byte register (Table 3) is the master
index that points to the various other registers within the
MAX6642. The register’s POR state is 0000 0000, so a
Receive Byte transmission (a protocol that lacks the
±1°C, SMBus-Compatible Remote/Local
Temperature Sensor with Overtemperature Alarm
8 _______________________________________________________________________________________
A D D R ESS PO R ST A T E F U N C T IO N
00h 00h ( 0000 0000) Read l ocal tem p er atur e
01h 00h ( 0000 0000) Read r em ote tem p er atur e
02h N /A Read status b yte
03h 10h ( 0001 0000) Read confi g ur ati on b yte
05h 46h ( 0100 0110) + 70 ° C Read l ocal hi g h l i m i t
07h 78h ( 0111 1000) + 120 ° C Read r em ote hi g h l i m i t
09h N /A W r i te confi g ur ati on b yte
0Bh N /A W r i te l ocal hi g h l i m i t
0D h N /A W r i te r em ote hi g h l i m i t
0Fh N /A S i ng l e shot
10h 0000 0000
Read r em ote extend ed
tem p er atur e
11h 0000 0000
Read i nter nal extend ed
tem p er atur e
FE h 4D h ( 0100 1101) Read m anufactur er ID
Table 3. Command-Byte Assignments
BIT NAME POR STATE FUNCTION
7 (MSB) MASK1 0 A 1 masks off (disables) the ALERT interrupts.
6 STOP/RUN 0 A 1 puts the MAX6642 into standby mode.
5 External only 0
A 1 disables local temperature measurements so that only
remote temperature is measured. The measurement rate
becomes 8Hz.
4
Fault
queue
1
0: ALERT is set by a single fault. 1: Two consecutive faults
are required to set ALERT.
3 to 0 — 0000 Reserved.
Table 4. Configuration-Byte Bit Assignments
BIT NAME POR STATE FUNCTION
7 (MSB) BUSY 0 A 1 indicates the MAX6642 is busy converting.
6 LHIGH 0
A 1 indicates an internal high-temperature fault. Clear
LHIGH with a POR or by reading the status byte.
5 — 0 Reserved.
4 RHIGH 0
A 1 indicates an external high-temperature fault. Clear
RHIGH with a POR or by reading the status byte.
3 — 0 Reserved.
2 OPEN 0
A 1 indicates a diode open condition. Clear OPEN with a
POR or by reading the status byte when the condition no
longer exists.
1 to 0 — 0 Reserved.
Table 5. Status-Byte Bit Assignments