ADM1034ARQZ-R7 ON Semiconductor, ADM1034ARQZ-R7 Datasheet - Page 14

• Manufacturer Part Number: ADM1034ARQZ-R7
• Description: IC THERM/FAN SPEED CTLR 16-QSOP
• Manufacturer: ON Semiconductor

Specifications of ADM1034ARQZ-R7

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Temperature (°C) = (MSB − 64°C) + (LSB x 0.03125)
Example: MSB = 0101 0100 = 84d
LSB = 11100 = 28
Temperature °C = (84 – 64) + (28 x 0.03125) = 20.875
Remote Temperature Measurement
external diode sensors or diode−connected transistors, which
are connected to Pins 9 and 10 and Pins 11 and 12. These pins
are dedicated temperature input channels. The series
resistance cancellation (SRC) feature can automatically
cancel out the effect of up to 1 kW of resistance in series with
the remote thermal diode.
transistor, operated at a constant current, exhibits a negative
temperature coefficient of about −2 mV/°C. Unfortunately,
the absolute value of V
Table 4. Temperature Data Format − (Local
Temperature and Remote Temperature High Bytes)
Table 5. Local and Remote Sensor Extended
Resolution
The ADM1034 can measure the temperature of two
The forward voltage of a diode or diode−connected
Extended Resolution (5C)
Temperature (5C)
0.03125
0.0000
0.0625
−64°C
−40°C
−32°C
100°C
125°C
150°C
191°C
0.125
0.250
0.375
0.500
0.625
0.750
0.875
−2°C
−1°C
10°C
20°C
50°C
75°C
0°C
1°C
2°C
be
varies from device to device, and
Temperature Low Bits
Digital Output
0000 0000
0001 1000
0010 0000
0100 0000
0100 0001
0100 0010
0100 1010
0101 0100
1000 1011
1010 0100
0011 1110
0111 0010
1011 1101
1101 0110
0011 1111
1111 1111
00000
00001
00010
00100
01000
10000
10100
01100
11000
11100
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14
individual calibration is required to null this out. Therefore,
the technique is unsuitable for mass production.
measure the change in V
conditioning used to measure the output of an external
temperature sensor. It also shows the external sensor as a
substrate transistor, provided for temperature monitoring on
some microprocessors. The external sensor could work
equally well as a discrete transistor.
and should be linked to the base. If a PNP transistor is used,
the base is connected to the D− input and the emitter to the D+
input. If an NPN transistor is used, the emitter is connected to
the D− input and the base to the D+ input.
capacitor value up to 1000 pF may be placed between the D+
and D− inputs to filter the noise. However, additional
parasitic capacitance on the lines between D+, D−, and the
thermal diode should also be considered. The total
capacitance should never be greater than 1000 pF.
operating currents of I, (N1 x I), and (N2 x I). The resulting
waveform is passed through a 65 kHz low−pass filter to
remove noise, then to a chopper−stabilized amplifier that
amplifies and rectifies the waveform. This produces a dc
voltage proportional to DV
determine the temperature of the thermal diode, while
automatically compensating for any series resistance on the
D+ and/or D− lines. The temperature is stored in two
registers as a 13−bit word.
performed by averaging the results of 16 measurement cycles
at conversion rates of less than or equal to 8 Hz. An external
temperature measurement takes nominally 32 ms when
averaging is enabled and 6 ms when averaging is disabled.
ADM1034 can theoretically measure temperatures from
−64°C to +191.96875°C, although these are outside its
operating range. The extended temperature resolution data
format is shown in Table 5. The data for the local and remote
channels is stored in the extended temperature resolution
registers (Reg. 0x40 = Local, Reg. 0x42 = Remote 1, and
Reg. 0x44 = Remote 2).
Figure 26. Measuring Temperature by Using Discreet
2N3906
The ADM1034 operates at three different currents to
If a discrete transistor is used, the collector is not grounded,
If the sensor is used in a very noisy environment, a
To measure each DV
To further reduce the effects of noise, digital filtering is
One LSB of the ADC corresponds to 0.03125°C. The
D+
D–
ADM1034
Transistors
be
be
, the sensor is switched between
. Figure 27 shows the input signal
be
. These voltage measurements
2N3904
D+
D–
ADM1034