ADT7473ARQZ-1RL ON Semiconductor, ADT7473ARQZ-1RL Datasheet - Page 14

• Manufacturer Part Number: ADT7473ARQZ-1RL
• Description: IC REMOTE THERMAL CTLR 16QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7473ARQZ-1RL

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Full Temp Accuracy: +/- 0.5 C
• Digital Output - Bus Interface: Serial (3-Wire, 4-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3. The V
Temperature Measurement Method
the negative temperature coefficient of a diode, measuring
the base−emitter voltage (VBE) of a transistor operated at
constant current. Unfortunately, this technique requires
calibration to null out the effect of the absolute value of
VBE, which varies from device to device.
measures the change in VBE when the device is operated at
three different currents. Previous 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.
Table 5. 10−Bit ADC Output Code vs. V
A simple method of measuring temperature is to exploit
The technique used in the ADT7473/ADT7473−1
V
CC
CC
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
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
1.100 to 1.1042
2.200 to 2.2042
3.300 to 3.3042
(3.3 V
output codes listed assume that V
<0.0042
>4.3957
−
−
−
−
IN
) (Note 3)
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
CC
IN
<0.00293
>2.9970
is 3.3 V.
V
CCP
−
−
−
−
http://onsemi.com
ADC Output
14
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 ground, but is
biased above ground by an internal diode at the D− input. C1
can optionally be added as a noise filter (recommended
maximum value 1000 pF). However, a better option in noisy
environments is to add a filter, as described in the Noise
Filtering section.
Figure 24 shows the input signal conditioning used to
256 (
512 (
768 (
Decimal
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1/4
1/2
3/4
0
1
2
3
4
5
6
7
8
−
−
−
−
scale)
scale)
scale)
Binary (10 Bits)
00000000 00
00000000 01
00000000 10
00000001 00
00000001 01
00000001 10
00000010 00
01000000 00
10000000 00
00000000 11
00000001 11
11000000 00
11111101 01
11111101 10
11111101 11
11111110 00
11111110 01
11111110 10
11111110 11
11111111 00
11111111 01
11111111 10
11111111 11
−
−
−
−