ADM1034ARQZ-REEL View Datasheet(PDF) - ON Semiconductor
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ADM1034ARQZ-REEL Datasheet PDF : 39 Pages
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ADM1034
Table 14. Status Register 2 (Reg. 0x50)
Bit # Name
Description
7
LT
1 = Local THERM temperature limit has
been exceeded.
6
R1T 1 = Remote 1 THERM temperature limit
has been exceeded.
5
R2T 1 = Remote 2 THERM temperature limit
has been exceeded.
4
T% 1 = THERM % on−time limit has been
exceeded.
3
TA
1 = One of the THERM limits has been
exceeded; and the THERM output signal
has been asserted.
2
TS 1 = THERM state. Indicates the THERM
pin is active; clears on a read if THERM
is not active. Does not generate an
ALERT in ALERT comp mode.
1
Res Reserved.
0
Res Reserved.
the ALERT output remains low until the corresponding
status register is read or until an ARA is completed (as long
as no other measurement is outside its limits).
For comp mode, set the ALERT configuration bit (Bit 3)
of Configuration Register 1 (Address 0x01) to1.
In comp mode, the ALERT output is automatically pulled
low when a measurement goes outside its programmed limits.
Once the measurement falls back within its limits (and
assuming no other measurement channel is outside its limits),
the ALERT output is automatically pulled high again.
The main difference between the two modes is that the
SMBusALERT does not reset without software intervention,
whereas the comp mode ALERT output automatically resets.
TEMPERATURE
LIMITS
ALERT, 70°C
Table 15. Status Register 3 (Reg. 0x51)
Bit # Name
Description
7
F1S
1 = Fan 1 has stalled.
6
FA
1 = Fan alarm speed. Fan1 and Fan 2
are running at alarm speed.
5
F2S
1 = Fan 2 has stalled.
4
Res
Reserved.
3
Res
Reserved.
2
Res
Reserved.
1
Res
Reserved.
0
ALERT 1 = ALERT low; indicates the ALERT
line has been pulled low.
ALERT Interrupt Behavior
The ADM1034 generates an ALERT whenever an
out−of−limit measurement is made (if it is not masked out).
The user can also detect out−of−limit conditions by polling
the ADM1034 status registers. It is important to note how
the SMBus ALERT output behaves when writing interrupt
handler software.
The ALERT output on the ADM1034 can be programmed
to operate in either SMBusALERT mode or in comp mode.
In SMBusALERT mode, the ALERT output remains low
until the measurement falls back within its programmed
limits and either the status register is read or an ARA is
completed. In comp mode, the ALERT output automatically
resets once the temperature measurement falls back within
the programmed limits.
Configuring the ALERT Output
For SMBusALERT mode, set the ALERT configuration bit
(Bit 3) of the Configuration Register 1 (Address 0x01) to 0.
In SMBusALERT mode, a status bit is set when a
measurement goes outside of its programmed limit. If the
corresponding mask bit is not set, the ALERT output is
pulled low. If the measured value falls back within the limits,
SMBusALERT
ALERT COMP
TIME
CLEARED
ON READ
Figure 30. ALERT Comparator and SMBusALERT
Outputs
Handling SMBusALERT Interrupts
HIGH LIMIT
TEMPERATURE
”STICKY”
STATUS BIT
CLEARED ON READ
(TEMP BELOW LIMIT)
TEMP BACK IN LIMIT
(STATUS BIT STAYS SET)
SMBusALERT
INTERRUPT
MASK BIT SET
INTERRUPT MASK BIT
CLEARED
(SMBusALERT REARMED)
Figure 31. Handling SMBusALERT
To prevent tie−ups due to service interrupts, follow these
steps:
1. Detect an SMBus assertion.
2. Enter the interrupt handler.
3. Read the status register to identify the interrupt
source.
4. Mask the interrupt source by setting the
appropriate mask bit in the interrupt mask registers
(from Reg. 0x08 to Reg. 0x0A).
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