Rainbow Electronics MAX6681 - Manual (Page 11)

ture returns within the limits. An open diode also sets
this output.
Alert Response Address
The SMBus Alert Response interrupt pointer provides
quick fault identification for simple slave devices that
lack the complex, expensive logic needed to be a bus
master. Upon receiving an ALERT interrupt signal, the
host master can broadcast a Receive Byte transmission
to the Alert Response slave address (see the Slave
Addresses section). Then, any slave device that gener-
ated an interrupt, attempts to identify itself by putting its
own address on the bus (Table 4).
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
MAX6680/MAX6681
±1°C Fail-Safe Remote/Local Temperature
Sensors with SMBus Interface
______________________________________________________________________________________ 11
SMBCLK
A B C D E F G H I J K
SMBDATA
t
SU:STA
t HD:STA
t LOW t HIGH
t
SU:DAT
t
HD:DAT t SU:STO t
BUF
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SMBDATA LINE LOW
L M
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE
H = LSB OF DATA CLOCKED INTO SLAVE
I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION
M = NEW START CONDITION
Figure 4. SMBus Write Timing Diagram
SMBCLK
A B C D E F G H I J K
SMBDATA
t SU:STA t HD:STA
t LOW t HIGH
t SU:DAT t HD:DAT t SU:STO t
BUF
L M
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SMBDATA LINE LOW F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO MASTER
H = LSB OF DATA CLOCKED INTO MASTER
I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION
M = NEW START CONDITION
Figure 5. SMBus Read Timing Diagram