NCT1008CMN3R2G ON Semiconductor, NCT1008CMN3R2G Datasheet - Page 8

• Manufacturer Part Number: NCT1008CMN3R2G
• Description: IC TEMP MONITOR 2CH DGTL 8-DFN
• Manufacturer: ON Semiconductor

Specifications of NCT1008CMN3R2G

• Function: Temp Monitoring System (Sensor)
• Topology: ADC (Sigma Delta), Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 127°C, -64°C ~ 191°C
• Output Type: I²C™/SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 2.8 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-VFDFN Exposed Pad
• Full Temp Accuracy: +/- 1 C
• Digital Output - Bus Interface: 2 Wire, SMBus, I2C
• Digital Output - Number Of Bits: 8 bit
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 2.8 V
• Description/function: Temperature Monitor with Series Resistance Cancellation
• Supply Current: 240 uA
• 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. Table 1
lists the data format for the external 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 +127°C.
However, the NCT1008 can be operated using an extended
temperature range. The extended measurement range is
−64°C to +191°C. Therefore, the NCT1008 can be used to
measure the full temperature range of an external diode,
from −55°C to +150°C.
Table 1. Extended Temperature Resolution
(Remote Temperature Low Byte
The results of the local and remote temperature
The local temperature value is in Register 0x00 and has a
Extended Resolution
When reading the full external temperature value, read the
The temperature measurement range for both internal and
TRANSISTOR
0.00°C
0.25°C
0.50°C
0.75°C
SENSING
REMOTE
Remote Temperature Low Byte
C1
D–
D+
1
I
0 000 0000
0 100 0000
1 000 0000
1 100 0000
N1 y I
Figure 14. Input Signal Conditioning
N2 y I
DIODE
BIAS
http://onsemi.com
I
BIAS
1
CAPACITOR C1 IS OPTIONAL. IT IS ONLY NECESSARY IN NOISY ENVIRONMENTS.
C1 = 1000pF MAX.
f
C
8
V
= 65kHz
DD
2 of the configuration register to 1. The temperature range
is 0°C to 127°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 NCT1008 is limited
by the remote diode selection. The temperature registers 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. Above +150°C, they may lose
their semiconductor 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. Therefore, the temperature
measurement on the external channel may not be accurate
for temperatures that are outside the operating range of the
remote sensor.
temperature measurements can be made while the part is in
extended temperature mode, the NCT1008 itself should not
be exposed to temperatures greater than those specified in
the absolute maximum ratings section. Further, the device is
only guaranteed to operate 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 are
offset by 64°C in the offset binary data format. Examples of
temperatures in both data formats are shown in Table 2.
The extended temperature range is selected by setting Bit
In extended temperature mode, the upper and lower
It should be noted that although both local and remote
The NCT1008 has two temperature data formats. When the
TO ADC
V
V
OUT+
OUT–