ADM1034
Rev. 0 | Page 20 of 40
LIMITS, STATUS REGISTERS, AND INTERRUPTS
High and low limits are associated with each measurement
channel on the ADM1034. These can form the basis of system
status monitoring. A status bit can be set for any out-of-limit
condition and detected by polling the device. Alternatively,
SMBusALERTs can be generated to flag a processor or
microcontroller of an out-of-limit condition.
8-BIT LIMITS
The following is a list of all the 8-bit limits on the ADM1034:
Table 14. Temperature Limit Registers
Register
Description
Default
0x0B
Local High Limit
0x8B (75°C)
0x0C
Local Low Limit
0x54 (20°C)
0x0D
Local THERM Limit
0x95 (85°C)
0x0E
Remote 1 High Limit
0x8B (75°C)
0x0F
Remote 1 Low Limit
0x54 (20°C)
0x10
Remote 1 THERM Limit
0x95 (85°C)
0x11
Remote 2 High Limit
0x8B (75°C)
0x12
Remote 2 Low Limit
0x54 (20°C)
0x13
Remote 2 THERM Limit
0x95 (85°C)
Table 15. THERM Limit Register
Register
Description
Default
0x19
THERM % Limit
0xFF default
OUT-OF-LIMIT COMPARISONS
The ADM1034 measures all parameters in a round-robin
format and sets the appropriate status bit for out-of limit
conditions. Comparisons are made differently, depending on
whether the measured value is compared to a high or low limit.
High Limit: ≥ Comparison Performed
Low Limit: < Comparison Performed
ANALOG MONITORING CYCLE TIME
The analog monitoring cycle time begins on power-up, or, if
monitoring has been disabled, by writing a 1 to the monitor/
STBY bit of Configuration Register 1, (Address 0x01). The ADC
measures each one of the analog inputs in turn; as each
measurement is completed, the result is automatically stored in
the appropriate value register. The round-robin monitoring
cycle continues unless it is disabled by writing a 0 to the
monitor/STBY bit (Bit 0) of Configuration Register 1
(Address 0x01).
The ADC performs round-robin conversions and takes 11 ms
for the local temperature measurement and 32 ms for each
remote temperature measurement with averaging enabled.
The total monitoring cycle time for the average temperatures is
therefore nominally
(2 × 32) + 11 = 75 ms
Once the conversion time elapses, the round robin starts again.
section.
Fan TACH measurements take place in parallel and are not
synchronized with the temperature measurements in any way.
STATUS REGISTERS
The results of limit comparisons are stored in the status
registers. A 1 represents an out-of-limit measurement; a
0 represents an in-limit measurement. The status registers are
located at Addresses 0x4F to 0x51.
If the measurement is outside its limits, the corresponding
status register bit is set to 1. It remains set at 1 until the
measurement falls back within its limits and it is read or until
an ARA is completed.
Poll the state of the various measurements by reading the status
registers over the serial bus. If Bit 0 (ALERT low) of Status
Register 3 (Address 0x51) is set, this means that the ALERT
output has been pulled low by the ADM1034.
Pin 14 can be configured as a SMBusALERT output. This
automatically notifies the system supervisor of an out-of-limit
condition. Reading the status register clears the status bit as long
as the error condition is gone.
Status register bits are sticky. Whenever a status bit is set due to
an out-of-limit condition, it remains set—even after the
triggering event has gone. The only way to clear the status bit is
to read the status register (after the event has gone). Interrupt
mask registers (Reg. 0x08, Reg. 0x09, Reg. 0x0A) allow
individual interrupt sources to be masked from causing an
ALERT. However, if one of these masked interrupt sources goes
out of limit, its associated status bit is set in the status register.