ADM1032ARM ON Semiconductor, ADM1032ARM Datasheet - Page 13



Manufacturer Part Number
ON Semiconductor

Specifications of ADM1032ARM

Rohs Status
RoHS non-compliant
Temp Monitoring System (Sensor)
ADC, Comparator, Multiplexer, Register Bank
Sensor Type
External & Internal
Sensing Temperature
0°C ~ 100°C, External Sensor
Output Type
Output Alarm
Output Fan
Voltage - Supply
3 V ~ 5.5 V
Operating Temperature
0°C ~ 100°C
Mounting Type
Surface Mount
Package / Case
8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
Low Power Standby Mode
by setting Bit 6 of the configuration register. When Bit 6 is
low, the ADM1032 operates normally. When Bit 6 is high,
the ADC is inhibited and any conversion in progress is
terminated without writing the result to the corresponding
value register.
standby mode is reduced to less than 10 mA if there is no
SMBus activity, or 100 mA if there are clock and data signals
on the bus.
initiate a one−shot conversion of both channels by writing
XXh to the one−shot register (Address 0Fh), after which the
device returns to standby. It is also possible to write new
values to the limit register while it is in standby. If the values
stored in the temperature value registers are now outside the
new limits, an ALERT is generated even though the
ADM1032 is still in standby.
The ADM1032 Interrupt System
THERM. These have different functions. ALERT responds
to violations of software−programmed temperature limits
and is maskable. THERM is intended as a fail−safe interrupt
output that cannot be masked.
temperature limit, the ALERT pin is asserted low to indicate
an out−of−limit condition. If the temperature is within the
programmed low and high temperature limits, no interrupt
is generated.
ALERT pin is asserted low to indicate an overtemperature
condition. A local and remote THERM limit can be
programmed into the device to set the temperature limit
above which the overtemperature THERM pin is asserted
low. This temperature limit should be equal to or greater than
the high temperature limit programmed.
The ADM1032 can be put into a low power standby mode
The SMBus is still enabled. Power consumption in the
When the device is in standby mode, it is still possible to
The ADM1032 has two interrupt outputs, ALERT and
If the temperature goes equal to or below the lower
If the temperature exceeds the high temperature limit, the
The behavior of the high limit and THERM limit is as
4. If more than one device’s ALERT output is low,
5. Once the ADM1032 has responded to the alert
1. If either temperature measured exceeds the high
seven bits, an LSB of 1 is added. The address of
the device is now known, and it can be
interrogated in the usual way.
the one with the lowest device address has priority
in accordance with normal SMBus arbitration.
response address, it resets its ALERT output,
provided that the error condition that caused the
ALERT no longer exists. If the SMBALERT line
remains low, the master sends ARA again, and so
on until all devices whose ALERT outputs were
low have responded.
temperature limit, the ALERT output is asserted
cooling fan cycling on and off. The power−on default value
is 10°C, but this can be reprogrammed to any value after
powerup. This hysteresis value applies to both the local and
remote channels.
maximum performance from the system by only slowing it
down should it be at a critical temperature.
same power supply as the ADM1032, unlike the SMBus
signals (SDATA, SCLK, and ALERT) that can be pulled to
a different power rail, usually that of the SMBus controller.
Sensor Fault Detection
detects if the external sensor diode is open circuit. This is a
simple voltage comparator that trips if the voltage at D+
exceeds V
comparator is checked when a conversion is initiated and
sets Bit 2 of the status register if a fault is detected.
measuring range, for example, due to the diode being
short−circuited, the ADC outputs −128 (1000 0000). Since
the normal operating temperature range of the device only
extends down to 0°C, this output code should never be seen
in normal operation, so it can be interpreted as a fault
condition. Since it is outside the power−on default low
temperature limit (0°C) and any low limit that would
normally be programmed, a short−circuit sensor causes an
SMBus alert.
Table 9. THERM Hysteresis Sample Values
A THERM hysteresis value is provided to prevent a
Using these two limits in this way, allows the user to gain
The THERM signal is open drain and requires a pullup to
At the D+ input, the ADM1032 has a fault detector that
If the remote sensor voltage falls below the normal
THERM Hysteresis
. The THERM signal must always be pulled up to the
2. If the local or remote temperature continues to
Figure 17. Operation of the THERM Output
increase and either one exceeds the THERM limit,
the THERM output asserts low. This can be used
to throttle the CPU clock or switch on a fan.
− 1.0 V (typical). The output of this
Binary Representation
0 000 0000
0 000 0001
0 000 1010

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