ADM1031ARQ-REEL7 ON Semiconductor, ADM1031ARQ-REEL7 Datasheet - Page 9

• Manufacturer Part Number: ADM1031ARQ-REEL7
• Description: IC SENSOR 2-TEMP/FAN CTRL 16QSOP
• Manufacturer: ON Semiconductor

Specifications of ADM1031ARQ-REEL7

• Rohs Status: RoHS non-compliant
• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 100°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP

Alert Response Address
devices that allows an interrupting device to identify itself
to the host when multiple devices exist on the same bus.
be used as an SMBALERT. One or more INT outputs can be
connected to a common SMBALERT line connected to the
master. If a device’s INT line goes low, the following
procedure occurs:
Temperature Measurement System
Internal Measurement
sensor. The on−chip ADC performs conversions on the
output of this sensor and outputs the temperature data in
10−bit twos complement format. The resolution of the local
temperature sensor is 0.25°C. The format of the temperature
data is shown in Table 2.
Alert Response Address (ARA) is a feature of SMBus
The INT output can be used as an interrupt output or can
The ADM1031 contains an on−chip bandgap temperature
1. SMBALERT is pulled low.
2. Master initiates a read operation and sends the
3. The device whose INT output is low responds to
4. If more than one device’s INT output is low, the
5. Once the ADM1031 has responded to the alert
Alert Response Address (ARA = 0001 100). This
is a general call address that must not be used as a
specific device address.
the alert response address, and the master reads its
device address. The address of the device is now
known and can be interrogated in the usual way.
one with the lowest device address has priority, in
accordance with normal SMBus arbitration.
response address, it resets its INT output.
However, if the error condition that caused the
interrupt persists, then INT is reasserted on the
next monitoring cycle.
SDA
SCL
SDA
SCL
START BY
MASTER
START BY
MASTER
1
0
1
0
1
1
Figure 17. Reading Data from a Previously Selected Register
SERIAL BUS ADDRESS BYTE
Figure 16. Writing to the Address Pointer Register Only
SERIAL BUS ADDRESS BYTE
0
0
1
FRAME 1
1
FRAME 1
1
1
A1
A1
http://onsemi.com
A0
A0
R/W
R/W
9
ADM1031
ACK. BY
ADM1031
ACK. BY
9
External Measurement
external diode sensors or diode−connected transistors,
connected to Pins 9 and 10, and Pins 11 and 12.
function of Pin 7 is as a THERM input/output and is used to
flag overtemperature conditions.
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. As a result,
the technique is unsuitable for mass production.
change in V
currents.
measure the output of an external temperature sensor. This
figure shows the external sensor as a substrate transistor,
provided
microprocessors, but it could equally well be a discrete
transistor.
9
The ADM1031 can measure the temperatures of two
These pins are dedicated temperature input channels. The
The forward voltage of a diode or diode−connected
The technique used in the ADM1031 is to measure the
This is given by: DVBE = KT/q × In (N)
Figure 18 shows the input signal conditioning used to
D7
where:
D7
1
1
D6
D6
K is Boltzmann’s constant.
q is charge on the carrier.
T is absolute temperature in Kelvins.
N is ratio of the two currents.
BE
for
ADDRESS POINTER REGISTER BYTE
D5
DATA BYTE FROM ADM1031
D5
when the device is operated at two different
temperature
D4
D4
FRAME 2
BE
FRAME 2
D3
, varies from device to device, and
D3
D2
D2
monitoring
D1
D1
D0
D0
BY MASTER
ADM1031
NO ACK.
ACK. BY
9
9
on
STOP BY
STOP BY
MASTER
MASTER
some