Diode fault alarm – Rainbow Electronics MAX6659 User Manual
Page 10
MAX6657/MAX6658/MAX6659
1) Put the MAX6657/MAX6658/MAX6659 into standby
mode by setting bit 6 of the Configuration register to
1. Initiate a one-shot conversion using Command
Byte 0Fh. When this conversion is complete, read
the contents of the Temperature Data registers.
2) If the MAX6657/MAX6658/MAX6659 are in run mode,
read the Status register. If a conversion is in
progress, the BUSY bit is set to 1. Wait for the con-
version to complete as indicated by the BUSY bit
being set to 0, then read the Temperature Data reg-
isters. Note that the power-on reset sets the conver-
sion rate to 16Hz, so no extended data is valid with-
out reducing the conversion rate to 4Hz or less.
Diode Fault Alarm
There is a continuity fault detector at DXP that detects
an open circuit between DXP and DXN, or a DXP short
to V
CC
, GND, or DXN. If an open or short circuit exists,
the external temperature register is loaded with 1000
0000. Additionally, if the fault is an open circuit, bit 2
(OPEN) of the status byte is set to 1 and the ALERT con-
dition is activated at the end of the conversion.
Immediately after POR, the Status register indicates that
no fault is present until the end of the first conversion.
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______________________________________________________________________________________
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 4. SMBus Read 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
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 3. SMBus Write Timing Diagram
±1°C, SMBus-Compatible Remote/Local Temperature
Sensors with Overtemperature Alarms