ADM1033ARQZ-REEL7 ON Semiconductor, ADM1033ARQZ-REEL7 Datasheet - Page 13

• Manufacturer Part Number: ADM1033ARQZ-REEL7
• Description: IC THERM/FAN SPEED CTRLR 16-QSOP
• Manufacturer: ON Semiconductor

Specifications of ADM1033ARQZ-REEL7

• 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 ~ 3.6 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 Measurement System
Internal Temperature Measurement
sensor. The on−chip ADC performs conversions on the
sensor’s output, outputting the data in 13−bit format. The
resolution of the local temperature sensor is 0.03125°C.
Table 5 shows the same for the LSBs. To ensure accurate
readings, read the LSBs first. This locks the current LSBs
and MSBs until the MSBs are read. They then start to update
again. (Reading only the MSBs does not lock the registers.)
Temperature updates to the look−up table take place in
parallel; so fan speeds may be updated even if the MSBs are
locked.
Table 4. Temperature Data Format − (Local
Temperature and Remote Temperature High Bytes)
If a device’s ALERT line goes low, the following occurs:
The ADM1033 contains an on−chip band gap temperature
Table 4 shows the format of the temperature data MSBs.
1. SMBusALERT is pulled low.
2. The master initiates a receive byte operation and
3. The device with the low ALERT output responds
4. If low ALERT output is detected in more than one
5. Once the ADM1033 has responded to the ARA, it
sends the alert response address (ARA 0001 100).
This is a general call address that must not be used
as a specific address.
to the ARA, and the master reads its device
address. Once the address is known, it can be
interrogated in the usual way.
device, the one with the lowest device address has
priority, in accordance with normal SMBus
arbitration.
resets its ALERT output. However, if the error
persists, the ALERT is re−asserted on the next
monitoring cycle.
Temperature (5C)
−64°C
−40°C
−32°C
100°C
125°C
150°C
191°C
−2°C
−1°C
10°C
20°C
50°C
75°C
0°C
1°C
2°C
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
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13
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
diode sensor or diode−connected transistor, which are
connected to Pins 9 and 10. 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
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.
Table 5. Local and Remote Sensor Extended
Resolution
Figure 26. Measuring Temperature by Using Discreet
2N3906
The ADM1033 can measure the temperature of external
The forward voltage of a diode or diode−connected
The ADM1033 operates at three different currents to
If a discrete transistor is used, the collector is not grounded,
Extended Resolution (5C)
0.03125
0.0000
0.0625
0.125
0.250
0.375
0.500
0.625
0.750
0.875
D+
D–
ADM1033
BE
Transistors
BE
varies from device to device, and
. Figure 27 shows the input signal
2N3904
Temperature Low Bits
00000
00001
00010
00100
01000
01100
10000
10100
11000
11100
D+
D–
ADM1033