ADT7460ARQZ-RL7 ONSEMI [ON Semiconductor], ADT7460ARQZ-RL7 Datasheet - Page 19

• Manufacturer Part Number: ADT7460ARQZ-RL7
• Description: dBCOOL Remote Thermal Monitor and Fan Controller
• Manufacturer: ONSEMI [ON Semiconductor]

Analog Monitoring Cycle Time
the start bit (Bit 0) of Configuration Register 1 (Reg. 0x40).
The ADC measures each analog input in turn and, as each
measurement is completed, the result is automatically stored
in the appropriate value register. This round−robin
monitoring cycle continues unless disabled by writing a 0 to
Bit 0 of Configuration Register 1.
the time taken to monitor all the analog inputs is normally not
of interest, since the most recently measured value of any
input can be read out at any time. For applications where the
monitoring cycle time is important, it can easily be calculated.
conversions and takes 11.38 ms for each voltage
measurement, 12 ms for a local temperature reading, and
25.5 ms for each remote temperature reading.
temperature monitoring is, therefore, nominally:
channels are measured approximately every 120 ms.
synchronized with the analog measurements in any way.
Status Registers
Registers 1 and 2. The status register bit for each channel
reflects the status of the last measurement and limit
comparison on that channel. If a measurement is within
limits, the corresponding status register bit is cleared to 0. If
the measurement is out−of−limits, the corresponding status
register bit is set to 1.
polled by reading the status registers over the serial bus. In
Bit 7 (OOL) of Status Register 1 (Reg. 0x41), 1 means that
an out−of−limit event has been flagged in Status Register 2.
This means that you need only read Status Register 2 when
this bit is set. Alternatively, Pin 5 or Pin 14 can be configured
as an SMBALERT output. This automatically notifies the
system supervisor of an out−of−limit condition. Reading the
status registers clears the appropriate status bit as long as the
error condition that caused the interrupt has cleared. Status
register bits are “sticky.” Whenever a status bit is set,
indicating an out−of−limit condition, it remains set even if the
event that caused it has gone away (until read). The only way
to clear the status bit is to read the status register after the
event has gone away. Interrupt status mask registers (Reg.
0x74, 0x75) allow individual interrupt sources to be masked
from causing an SMBALERT. However, if one of these
masked interrupt sources goes out−of−limit, its associated
status bit is set in the interrupt status registers.
The analog monitoring cycle begins when a 1 is written to
As the ADC is normally allowed to free−run in this manner,
The total number of channels measured is
As mentioned previously, the ADC performs round−robin
The total monitoring cycle time for averaged voltage and
The round robin starts again 35 ms later. Therefore, all
Fan TACH measurements are made in parallel and are not
The results of limit comparisons are stored in Status
The state of the various measurement channels may be
♦
♦
♦
( 2
Two supply voltage inputs (2.5 V and V
Local temperature
Two remote temperatures
11.38 ) ) 12 ( 2
25.5 ) + 85.76 ms
CC
)
(eq. 1)
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ADT7460
19
Table 20. Status Register 1 (Reg. 0x41)
Table 21. Status Register 2 (Reg. 0x42)
Bit
Bit
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
Mnemonic
Mnemonic
FAN3
FAN2
FAN1
2.5 V
OOL
VCC
OVT
R2T
R1T
F4P
D2
D1
LT
−
−
−
Figure 32. Status Register 1
Figure 33. Status Register 2
MONITORED THROUGH STATUS REG 2
OOL = 1 DENOTES A PARAMETER
1 denotes a bit in Status Register 2 is
set and Status Register 2 should be
read.
1 indicates that the Remote 2
temperature high or low limit has been
exceeded.
1 indicates that the Local temperature
high or low limit has been exceeded.
1 indicates that the Remote 1
temperature high or low limit has been
exceeded.
Unused
1 indicates that the VCC high or low
limit has been exceeded.
Unused
1 indicates that the 2.5 V high or low
limit has been exceeded.
1 indicates an open or short on
D2+/D2− inputs.
1 indicates an open or short on
D2+/D2− inputs.
1 indicates that Fan 4 has dropped
below minimum speed. Alternatively,
indicates that THERM timer limit has
been exceeded if the THERM timer
function is used.
1 indicates that Fan 3 has dropped
below minimum speed.
1 indicates that Fan 2 has dropped
below minimum speed.
1 indicates that Fan 1 has dropped
below minimum speed.
1 indicates that a THERM
overtemperature limit has been
exceeded.
Unused
F4P = 1, FAN 4 OR THERM
TIMER IS OUT−OF−LIMIT
IS OUT−OF−LIMIT
Description
Description