EVAL-ADT7467EBZ ON Semiconductor, EVAL-ADT7467EBZ Datasheet - Page 16

• Manufacturer Part Number: EVAL-ADT7467EBZ
• Description: BOARD EVALUATION FOR ADT7467
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of EVAL-ADT7467EBZ

• Sensor Type: Temperature
• Sensing Range: -40°C ~ 120°C
• Interface: SMBus (2-Wire/I²C)
• Sensitivity: ±1.5°C
• Voltage - Supply: 3 V ~ 5.5 V
• Embedded: No
• Utilized Ic / Part: ADT7467
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADT7467
Table 6. 10-Bit Analog-to-Digital Output Code vs. V
V
<0.0065
0.0065 to 0.0130
0.0130 to 0.0195
0.0195 to 0.0260
0.0260 to 0.0325
0.0325 to 0.0390
0.0390 to 0.0455
0.0455 to 0.0521
0.0521 to 0.0586
1.6675 to 1.6740
3.330 to 3.3415
5.0025 to 5.0090
6.5983 to 6.6048
6.6048 to 6.6113
6.6113 to 6.6178
6.6178 to 6.6244
6.6244 to 6.6309
6.6309 to 6.6374
6.6374 to 6.4390
6.6439 to 6.6504
6.6504 to 6.6569
6.6569 to 6.6634
>6.6634
TEMPERATURE MEASUREMENT
A simple method of measuring temperature is to exploit the
negative temperature coefficient of a diode, measuring the base-
emitter voltage (V
current. Unfortunately, this technique requires calibration to
null the effect of the absolute value of V
each device.
The technique used in the ADT7467 is to measure the change
in V
devices have used only two operating currents, but the use of a
third current allows automatic cancellation of resistances in
series with the external temperature sensor.
Figure 24 shows the input signal conditioning used to measure
the output of an external temperature sensor. This figure shows
the external sensor as a substrate transistor, but it could equally
be a discrete transistor. If a discrete transistor is used, the
collector is not grounded and should be linked to the base. To
prevent ground noise from interfering with the measurement,
the more negative terminal of the sensor is not referenced to
CC
(5 V
BE
when the device is operated at three currents. Previous
IN
)
BE
) of a transistor operated at constant
V
<0.0042
0.0042 to 0.0085
0.0085 to 0.0128
0.0128 to 0.0171
0.0171 to 0.0214
0.0214 to 0.0257
0.0257 to 0.0300
0.0300 to 0.0343
0.0343 to 0.0386
1.100 to 1.1042
2.200 to 2.2042
3.300 to 3.3042
4.3527 to 4.3570
4.3570 to 4.3613
4.3613 to 4.3656
4.3656 to 4.3699
4.3699 to 4.3742
4.3742 to 4.3785
4.3785 to 4.3828
4.3828 to 4.3871
4.3871 to 4.3914
4.3914 to 4.3957
>4.3957
CC
(3.3 V
Input Voltage
IN
)
BE
, which varies from
IN
Rev. 3 | Page 16 of 77 | www.onsemi.com
V
<0.00293
0.0293 to 0.0058
0.0058 to 0.0087
0.0087 to 0.0117
0.0117 to 0.0146
0.0146 to 0.0175
0.0175 to 0.0205
0.0205 to 0.0234
0.0234 to 0.0263
0.7500 to 0.7529
1.5000 to 1.5029
2.2500 to 2.2529
2.9677 to 2.9707
2.9707 to 2.9736
2.9736 to 2.9765
2.9765 to 2.9794
2.9794 to 2.9824
2.9824 to 2.9853
2.9853 to 2.9882
2.9882 to 2.9912
2.9912 to 2.9941
2.9941 to 2.9970
>2.9970
CCP
ground but is biased above ground by an internal diode at the
D− input. C1 can optionally be added as a noise filter (the
recommended maximum value is 1000 pF). However, a better
option in noisy environments is to add a filter as described in
the Noise Filtering section.
Local Temperature Measurement
The ADT7467 contains an on-chip band gap temperature
sensor whose output is digitized by the on-chip 10-bit ADC.
The 8-bit MSB temperature data is stored in the local tempera-
ture register (Address 0x26). Because both positive and negative
temperatures can be measured, the temperature data is stored in
Offset 64 format or twos complement format, as shown in
Table 7 and Table 8. Theoretically, the temperature sensor and
ADC can measure temperatures from −128°C to +127°C (or
−64°C to +191°C in the extended temperature range) with a
resolution of 0.25°C. However, this exceeds the operating
temperature range of the device, preventing local temperature
measurements outside the ADT7467 operating temperature range.
0
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
Decimal
1
2
3
4
5
6
7
8
…
256 (1/4 scale)
…
512 (1/2 scale)
…
768 (3/4 scale)
…
A/D Output
00000000 00
01000000 00
10000000 00
11000000 00
11111101 01
11111101 10
11111101 11
11111110 00
11111110 01
11111110 10
11111110 11
11111111 00
11111111 01
11111111 10
11111111 11
Binary (10 Bits)
00000000 01
00000000 10
00000000 11
00000001 00
00000001 01
00000001 10
00000001 11
00000010 00