ADT7461AARMZ-002 ON Semiconductor, ADT7461AARMZ-002 Datasheet - Page 10

• Manufacturer Part Number: ADT7461AARMZ-002
• Description: IC TEMP SENSOR DGTL 2CH 8-MSOP
• Manufacturer: ON Semiconductor

Specifications of ADT7461AARMZ-002

• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 127°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Full Temp Accuracy: +/- 2.5 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Temperature Sensor Function: Temp Sensor
• Interface Type: Serial (2-Wire)
• Package Type: MSOP
• Operating Temperature (min): -40C
• Operating Temperature (max): 125C
• Operating Temperature Classification: Automotive
• Operating Supply Voltage (min): 3V
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.6V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Conversion Rate Register
Address 0x0A at write. The lowest four bits of this register
are used to program the conversion rate by dividing the
internal oscillator clock by 1, 2, 4, 8, 16, 32, 64, 128, 256,
512, or 1024 to give conversion times from 15.5 ms (Code
0x0A) to 16 seconds (Code 0x00). For example, a
conversion rate of eight conversions per second means that
beginning at 125 ms intervals, the device performs a
conversion on the internal and the external temperature
channels.
back over the SMBus. The higher four bits of this register are
unused and must be set to 0. The default value of this register
is 0x08, giving a rate of 16 conversions per second. Use of
slower conversion times greatly reduces the device power
consumption.
Limit Registers
THERM temperature limits for both local and remote
temperature measurements. The remote temperature high
and low limits span two registers each, to contain an upper
and lower byte for each limit. There is also a THERM
hysteresis register. All limit registers can be written to, and
read back over, the SMBus. See Table 9 for details of the
limit register addresses and their power−on default values.
limit registers perform a > comparison, while the low limit
registers perform a ≤ comparison. For example, if the high
limit register is programmed with 80°C, then measuring
81°C results in an out−of−limit condition, setting a flag in
the status register. If the low limit register is programmed
with 0°C, measuring 0°C or lower results in an out−of−limit
condition.
THERM low. When Pin 6 is configured as THERM2,
exceeding either the local or remote high limit asserts
THERM2 low. A default hysteresis value of 10°C is
provided that applies to both THERM channels. This
Table 5. Conversion Rate Register Codes
The conversion rate register is Address 0x04 at read and
The conversion rate register can be written to and read
The ADT7461A has eight limit registers: high, low, and
When Pin 6 is configured as an ALERT output, the high
Exceeding either the local or remote THERM limit asserts
0x0B to 0xFF
Code
0x0A
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
Conversion/Second
Reserved
0.0625
0.125
0.25
0.5
16
32
64
1
2
4
8
Time (Seconds)
31.25 m
62.5 m
15.5 m
500 m
250 m
125 m
16
8
4
2
1
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10
hysteresis value can be reprogrammed to any value after
powerup (Register Address 0x21).
data format is the same as the temperature measurement data
format. Therefore, if the temperature measurement uses
default binary, then the temperature limits also use the
binary scale. If the temperature measurement scale is
switched, however, the temperature limits do not
automatically switch. The user must reprogram the limit
registers to the desired value in the correct data format. For
example, if the remote low limit is set at 10°C with the
default binary scale, the limit register value is 0000 1010b.
If the scale is switched to offset binary, the value in the low
temperature limit register needs to be reprogrammed to
0100 1010b.
Status Register
It contains status information for the ADT7461A.
ADC is busy converting. The other bits in this register flag the
out−of−limit temperature measurements (Bit 6 to Bit 3, and
Bit 1 to Bit 0) and the remote sensor open circuit (Bit 2).
applies: If the local temperature measurement exceeds its
limits, Bit 6 (high limit) or Bit 5 (low limit) of the status
register asserts to flag this condition. If the remote
temperature measurement exceeds its limits, then Bit 4 (high
limit) or Bit 3 (low limit) asserts. Bit 2 asserts to flag an open
circuit condition on the remote sensor. These five flags are
NOR’ed together, so if any of them is high, the ALERT
interrupt latch is set and the ALERT output goes low.
Bit 2, provided the error conditions causing the flags to be
set have gone away. A flag bit can be reset only if the
corresponding value register contains an in−limit
measurement or if the sensor is good.
status register. It resets when the ALERT output has been
serviced by the master reading the device address, provided
the error condition has gone away and the status register flag
bits are reset.
goes low to indicate that the temperature measurements are
outside the programmed limits. The THERM output does
not need to be reset, unlike the ALERT output. Once the
measurements are within the limits, the corresponding status
register bits are automatically reset and the THERM output
goes high. The user may add hysteresis by programming
Register 0x21. The THERM output is reset only when the
temperature falls to limit value minus the hysteresis value.
temperature limits are relevant. If Flag 6 and/or Flag 4 are
set, the THERM2 output goes low to indicate that the
temperature measurements are outside the programmed
limits. Flag 5 and Flag 3 have no effect on THERM2. The
behavior of THERM2 is otherwise the same as THERM.
It is important to remember that the temperature limits
The status register is a read−only register at Address 0x02.
When Bit 7 of the status register is high, it indicates that the
If Pin 6 is configured as an ALERT output, the following
Reading the status register clears the five flags, Bit 6 to
The ALERT interrupt latch is not reset by reading the
When Flag 1 and/or Flag 0 are set, the THERM output
When Pin 6 is configured as THERM2, only the high