ADT7421ARMZ-2RL7 ON Semiconductor, ADT7421ARMZ-2RL7 Datasheet - Page 7

• Manufacturer Part Number: ADT7421ARMZ-2RL7
• Description: IC TEMP MONITOR 8-MSOP
• Manufacturer: ON Semiconductor
• Type: Temperature Sensorr

Specifications of ADT7421ARMZ-2RL7

• Input Type: Logic
• Output Type: Logic
• Interface: 2-Wire SMBus
• Current - Supply: 4mA
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Full Temp Accuracy: +/- 2.75 C, +/- 3.25 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Temperature Measurement Results
measurements are stored in the local and remote temperature
value registers and 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 giving the external
temperature measurement a resolution of 0.25°C. The table
lists the data format for the external temperature low byte.
Table 1. Extended Temperature Resolution
(Remote Temperature Low Byte)
LSB first. This causes the MSB to be locked (that is, the
ADC does not write to it) until it is read. This feature ensures
that the results read back from the two registers come from
the same measurement.
Temperature Measurement Range
external measurements is, by default, 0°C to +125°C.
However, the ADT7421 can be operated using an extended
temperature range. The extended measurement range is
−40°C to +125°C.
Bit 2 of the configuration register to 1. The temperature
range is 0°C to 125°C when Bit 2 equals 0. A valid result is
available in the next measurement cycle after changing the
temperature range.
temperature that can be measured by the ADT7421 is limited
by the remote transistor selection. The temperature registers
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, read the
The temperature measurement range for both internal and
The extended temperature range is selected by setting
In extended temperature mode, the upper and lower
0.00°C
0.25°C
0.50°C
0.75°C
NOTE:
CAPACITOR C1 IS OPTIONAL. IT IS ONLY NECESSARY IN NOISY ENVIRONMENTS. C1 = 1000pF MAX.
TRANSISTOR
SENSING
REMOTE
Remote Temperature Low Byte
C1
D–
D+
0 000 0000
0 100 0000
1 000 0000
1 100 0000
I
Figure 9. Input Signal Conditioning
N1 y I
http://onsemi.com
N2 y I
DIODE
BIAS
I
BIAS
7
can have values from −40°C to +125°C. Most temperature
sensing transistors have a maximum temperature range of
−55°C to +150°C. Above +150°C, they may lose their
semiconductor characteristics and approximate conductors
instead.
temperature measurements can be made while the part is in
extended temperature mode, the ADT7421 itself should not
be exposed to temperatures greater than those specified in
the Absolute Maximum Ratings Table. Further, the device
is only guaranteed to operate as specified at ambient
temperatures from −40°C to +125°C.
Temperature Data Format
the temperature measurement range is from 0°C to 125°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 are offset by 64°C in the offset binary
data format. Examples of temperatures in both data formats
are shown in the following table.
Table 2. Temperature Data Format
(Temperature High Byte)
1. Offset binary scale temperature values are offset by 64°C.
2. Binary scale temperature measurement returns 0°C for all
3. Binary scale temperature measurement returns 125°C for all
f
C
It should be noted that although both local and remote
The ADT7421 has two temperature data formats. When
V
Temperature
temperatures < 0°C.
temperatures > 125°C.
= 65kHz
DD
+100°C
+125°C
−40°C
+10°C
+25°C
+50°C
+75°C
+1°C
0°C
0 000 0000
0 000 0000
0 000 0001
0 000 1010
0 001 1001
0 011 0010
0 100 1011
0 110 0100
0 111 1101
Binary
TO ADC
V
V
OUT+
OUT–
Offset Binary
0 001 1000
0 100 0000
0 100 0001
0 100 1010
0 101 1001
1 000 1011
1 010 0100
0 111 0010
1 011 1101