ADT7461ARMZ-2 ON Semiconductor, ADT7461ARMZ-2 Datasheet - Page 8

• Manufacturer Part Number: ADT7461ARMZ-2
• Description: IC SENSOR TEMP DGTL 2CH 8MSOP
• Manufacturer: ON Semiconductor

Specifications of ADT7461ARMZ-2

• 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 ~ 5.5 V
• Operating Temperature: -40°C ~ 120°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Temperature Measurement Results
measurements are stored in the local and remote temperature
value registers and are compared with limits programmed
into the local and remote high and low limit registers.
resolution of 1°C. The external temperature value is stored in
two registers, with the upper byte in Register 0x01 and the
lower byte in Register 0x10. Only the two MSBs in the external
temperature low byte are used. This gives the external
temperature measurement a resolution of 0.25°C. Table 1
shows the data format for the external temperature low byte.
high and low byte, the two registers should be read in
succession. Reading one register does not lock the other, so
both should be read before the next conversion finishes. In
practice, there is more than enough time to read both
registers, as transactions over the SMBus are significantly
faster than a conversion time.
Temperature Measurement Range
external measurements is, by default, 0°C to +127°C.
However, the ADT7461 can be operated using an extended
temperature range. It can measure the full temperature range
Table 1. Extended Temperature Resolution
(Remote Temperature Low Byte
Extended Resolution
The results of the local and remote temperature
The local temperature value is in Register 0x00 and has a
When reading the full external temperature value, both the
The temperature measurement range for both internal and
TRANSISTOR
SENSING
REMOTE
0.00°C
0.25°C
0.50°C
0.75°C
C1*
Remote Temperature Low Byte
D+
D–
Figure 15. Input Signal Conditioning Error vs. Series Resistance
I
0 000 0000
0 100 0000
1 000 0000
1 100 0000
N1
×
I
DIODE
BIAS
N2
×
I
I
BIAS
http://onsemi.com
LOW−PASS FILTER
*CAPACITOR C1 IS OPTIONAL. IT SHOULD ONLY BE USED IN NOISY ENVIRONMENTS.
f
C
= 65kHz
8
V
of an external diode, from −55°C to +150°C. The user can
switch between these two temperature ranges by setting or
clearing Bit 2 in the configuration register. A valid result is
available in the next measurement cycle after changing the
temperature range.
temperature that can be measured by the ADT7461 is
limited by the remote diode selection. The temperature
registers themselves can have values from −64°C to +191°C.
However, most temperature sensing diodes have a
maximum temperature range of −55°C to +150°C.
characteristics and approximate conductors instead. This
results in a diode short. In this case, a read of the temperature
result register gives the last good temperature measurement.
The user should be aware that the temperature measurement
on the external channel may not be accurate for temperatures
that are outside the operating range of the remote sensor.
can be made while the part is in extended temperature mode,
the ADT7461 itself should not be exposed to temperatures
greater than those specified in the Absolute Maximum
Ratings section. Also, the device is guaranteed to operate only
as specified at ambient temperatures from −40°C to +120°C.
Temperature Data Format
temperature measurement range is from 0°C to +127°C
(default), the temperature data format for both internal and
external temperature results is binary. When the measurement
range is in extended mode, an offset binary data format is used
for both internal and external results. Temperature values in
the offset binary data format are offset by 64°C. Examples of
temperatures in both data formats are shown in Table 2.
DD
In extended temperature mode, the upper and lower
Above 150°C, they may lose their semiconductor
While both local and remote temperature measurements
The ADT7461 has two temperature data formats. When the
V
TO ADC
V
OUT+
OUT–